Biology and control of Claviceps purpurea (Fr.) Tul. on male sterile wheat and barley
by Shivayogi Basaya Puranik
A thesis submitted to the Graduate Faculty in partial fulfillment of the requirements for the degree of
DOCTOR OF PHILOSOPHY in Plant Pathology
Montana State University
© Copyright by Shivayogi Basaya Puranik (1970)
Abstract:
The seriousness of ergot caused by Claviceps purpurea (Fr.) Tul. in male sterile barley and wheat has
prompted further study of the biology of this pathogen. For evaluation of various control measures, a
technique of inoculation was developed and involved the removal of the upper 2-4 mm of the glumes
prior to inoculation with a conidial suspension using an atomizer. Use of this technique resulted in
nearly 1007. head and floret infection whereas previously described methods resulted in 20-607. head
infection. Studies on inoculation density revealed that maximum infection occurred with 10^5 or more
conidia per ml. Studies on duration of infection period of unfertilized and fertilized ovaries indicated
that inoculation during and shortly after anthesis resulted in the highest levels of floret infection. With
unfertilized florets, susceptibility declined at 10 days and was lost completely 15 days after the
initiation of anthesis. Fertilized ovaries were susceptible right after fertilization. After the ovaries had
been fertilized for 4 days susceptibility decreased until no infection occurred 9 days after fertilization.
Many chemicals were screened for their effectiveness in inhibiting germination and growth of C.
purpurea. Benomyl at 10 ppm inhibited germination of conidia while growth was completely inhibited
at 20 ppm. Under field conditions using male sterile barley, 2400 ppm benomyl applied three times just
prior to and during anthesis gave some control of ergot.
To determine why benomyl did not give complete control various concentrations of benomyl were
applied to florets with the upper portion of their glumes removed which had been previously inoculated
with C. purpurea. Using this method, floret infection was reduced from 947. to 11% with 1000 ppm
benomyl and to 0% if a wetting agent such as Triton X-77 or Multifilm Buffer X was used along with
1000 ppm benomyl. This indicated that benomyl must reach the surface of the ovary at or before
infection to be effective since benomyl did not act as an eradicant against this pathogen. Under natural
conditions this will be very difficult to achieve, but various methods of application and different
formulations of benomyl may prove to be effective. In male sterile wheat, it was observed that Chris
had some degree of resistance in comparison to other varieties tested. While none of the control
measures tested was effective by itself, the possibility exists that a combination of one or more of them
might prove to be quite effective. This would include the use of resistant germplasm; the use of a
variety that produces tillers over a short time period; the use of a good pollinator variety to insure rapid
and complete fertilization; and the use of a systemic fungicide to provide protection during 10-15 days
after anthesis when the host is most susceptible. The lack of the necessary germplasm at present
hinders the testing of these possibilities. BIOLOGY AND CONTROL OF CLAVICEPS PURPUREA (F R .)
TUL. ON MALE STERILE WHEAT AND BARLEY
by
SHIVAYOGI BASAYA PURANIK
v
A t h e s i s s u b m itte d to th e G ra d u a te F a c u l t y i n p a r t i a l
f u l f i l l m e n t o f th e r e q u ir e m e n ts f o r t h e d e g re e
of
DOCTOR OF PHILOSOPHY
in
P l a n t P a th o lo g y
A pproved:
H ead, M ajo r D e p artm en t
C h airm an , E xam ining C om m ittee
G raduater Dean
MONTANA STATE UNIVERSITY
Bozem an, M ontana
D ecem ber, 1970
Iii
ACKNOWLEDGEMENT
I w ish to e x p r e s s my g r a t e f u l n e s s and a p p r e c i a t i o n t o my a d v i s o r
D r. D onald E . M ath re f o r th e g u id a n c e , c o n s t r u c t i v e c r i t i c i s m , and
en co u ra g em en t th r o u g h o u t th e c o u r s e o f t h i s i n v e s t i g a t i o n .
I am in d e b te d to D r. G. A. S t r o b e l , D r. E. L . S h a r p , and D r. S . J .
R ogers f o r t h e i r h e lp in p r e p a r a t i o n o f t h i s t h e s i s .
I s h o u ld a l s o l i k e to e s p e c i a l l y th a n k D r. G. A. S t r o b e l and
P r o f . R .F . E s l i c k f o r t h e i r en c o u ra g e m e n t and g u id a n c e i n my w o rk .
My g r a t e f u l th a n k s a r e a l s o due to D r. A. B ronnim ann and D r.
M.M. A fa n a s ie v f o r t h e i r h e lp i n t r a n s l a t i n g German and R u s s ia n
a rtic le s .
I s i n c e r e l y th a n k M r. Ray P r a t t , A s s i s t a n t E n to m o lo g is t f o r
s u g g e s tio n s and f o r s u p p ly in g i n s e c t i c i d e and w e tt in g a g e n t s .
S p e c i a l g r a t i t u d e i s e x te n d e d t o M rs. D a rle n e H a r p s te r f o r th e
ty p in g o f t h i s t h e s i s .
T hanks to M r. Jim Chacko f o r d ra w in g g r a p h s .
iv
TABLE OF CONTENTS
P age
V IT A ....................................................................................................................................
ACKNOWLEDGEMENT
........................................................
ii
ill
TABLE OF CONTENTS....................................................................................................
iv
LIST OF TABLES.............................................................................................................
vi
LIST OF F IG U R E S ..............................................................................................................v i i i
ABSTRACT...........................................................................................................................
ix
INTRODUCTION ..................................................................................................................
I
MATERIALS AND METHODS
8
..........................................................................................
P la n t m a te ria ls . . . . . . . . . . .
C u lt u r e s
........................
. . . .
8
..............................................
8
I n o c u l a t i o n te c h n iq u e . . . . . . . . . . .
C o n id ia l g e r m in a tio n
O vary e x t r a c t s
. . . . . . .
........................
.
9
.................................................
10
......................................................................
10
O vary w a s h i n g s ...............................................................................................
11
Honey dew e x t r a c t ...............................................................................
11
C hro m ato g rap h y
12
.................... . . . . . . . . . . . . . . . .
C h em icals ............................. . . . . . . .
P o is o n fo o d t e s t s
............................. . . .
. . . . . . . . . . . . .
B io a s s a y o f benom yl . . . . . . . . . . .
12
.................... . .
14
.................... . . .
15
R E S U L T S ...............................................
I n o c u l a t i o n te c h n iq u e . . . . . . . . . . . . . . . . . .
16
16
P age
In o cu lu m d e n s i t y
16
I n f e c t i o n p e r io d
20
V a rie ta l re a c tio n
28
C o n id ia l g e r m in a tio n
32
F u n g ic id e s t u d i e s .
39
DISCUSSION .............................
53
SUMMARY...........................................................................................................................
61
LITERATURE C IT E D ........................................................................................................
65
vi
LIST OF TABLES
P age
T a b le
T a b le
T a b le
T a b le
T a b le
T a b le
T a b le
T a b le
T a b le
T a b le
T a b le
T a b le
I
II
III
IV
V
VI
V II
V III
IX
X
XI
X II
A c o m p a riso n o f m eth o d s o f i n o c u l a t i o n
o f C la v ic e p s p u r p u r e a o n i n f e c t i o n o f
f l o r e t s o f g re e n h o u s e grown m ale s t e r i l e
b a rle y . . . . . . . . . . . . .
...................
. .
17
F e r t i l e b a r l e y s t e r i l i t y and s u s c e p t i ­
b i l i t y to e r g o t ..................................................................
29
S t e r i l i t y and s u s c e p t i b i l i t y o f e l i t e
l i n e s o f m a le s t e r i l e w h eat t o e r g o t . . . . .
30
D egree o f s u s c e p t i b i l i t y o f m ale s t e r i l e
w heat v a r i e t i e s to e r g o t . . . . . . . . . . .
31
S u s c e p t i b i l i t y o f g re e n h o u s e grown m ale
s t e r i l e w h eat v a r i e t i e s t o e r g o t . . . . . . .
33
R v a l u e s o f some a u t h e n t i c s u g a r s r e l a t i v e
t § th o s e from o v a r y e x t r a c t . . . . . . . . .
34
E f f e c t o f m ale s t e r i l e b a r l e y o v a ry e t h a n o l i c
e x t r a c t f r a c t i o n s o n t h e g e r m in a tio n o f
c o n i d ia o f C la v ic e p s p u r p u r e a ..................................
35
E f f e c t o f c a rb o n s o u r c e and pH on g e rm in ­
a t i o n o f c o n i d i a o f C la v ic e p s p u r p u r e a . . . .
37
E f f e c t o f g lu c o s e c o n c e n t r a t i o n on g erm in ­
a t i o n o f c o n i d ia o f C la v ic e p s p u r p u r e a . . . .
38
E f f e c t o f pH on g ro w th o f C la v ic e p s
p u r p u r e a o n ACD m e d ia ................................. ....
40
E f f e c t o f b e n o m y l, nabam , and D ith a n e
M 45 on m y c e lia l g ro w th o f C la v lc e p s on
ACD a g a r .....................................................................................
41
E f f e c t o f v a r i o u s c o n c e n t r a t i o n s o f D ith a n e
M 45 and benom yl o n m y c e lia l d r y w e ig h t o f
C la v ic e p s p u r p u r e a on ACD m e d ia .............................
42
v ii
P age
T a b le
T a b le
T a b le
T a b le
T a b le
T a b le
X III
XIV
XV
XVI
XVII
X V III
C o n tr o l o f e r g o t i n m ale s t e r i l e
b a r l e y u n d e r f i e l d c o n d i tio n s w ith
v a r io u s c h e m ic a ls ................... .... ......................................
44
A p p lic a tio n o f f u n g ic i d e s t o t h e s o i l
a n d /o r f o l i a g e and h e a d s o f f i e l d grown
m ale s t e r i l e b a r l e y f o r c o n t r o l o f e r g o t . . .
45
F o l i a r and h e a d a p p l i c a t i o n o f benom yl
o r d ia z in o n f o r c o n t r o l o f e r g o t i n f i e l d
grown m ale s t e r i l e b a r l e y ................................. • .
47
F u n g ic i d a l c o n t r o l o f e r g o t i n f i e l d
grown m ale s t e r i l e b a r l e y w ith c l ip p e d
glum es . . . . . . . . . . . . . . . . . . . .
48
C o n tr o l o f e r g o t i n g re e n h o u s e grown
m a le s t e r i l e b a r l e y w ith b en o m y l. E f f e c t
o f f u n g i c i d e c o n c e n t r a t i o n and u s e o f
w e t t i n g a g e n t s ............................
50
E f f e c t i v e n e s s o f benom yl a s an e r a d i c a n t
o f e r g o t i n f e c t i o n i n g re e n h o u s e grown
m ale s t e r i l e b a r l e y
. . . . . .
.............................
51
v iii
LIST OF FIGURES
P age
F ig u r e I
F ig u r e 2
F ig u r e 3
F ig u r e 4
M ale s t e r i l e b a r l e y h e a d s show ing th e
d e g re e o f glum e m o d i f i c a t i o n u s e d i n
i n o c u l a t i o n s t u d i e s . ....................................................
19
The e f f e c t o f in o c u lu m d e n s i t y o f
C la v ic e p s p u r p u r e a on i n f e c t i o n o f
n o n - f e f t i l i z e d f l o r e t s o f m ale s t e r i l e
b a r l e y and w h eat . . . . . . . . . . . . . . .
22
The r e l a t i o n o f a n t h e s i s o f u n f e r t i l ­
iz e d f l o r e t s o f m a le s t e r i l e b a r l e y to
s u s c e p t i b i l i t y to C la v ic e p s p u r p u r e a . . . . .
25
The e f f e c t o f f e r t i l i z a t i o n o f m ale
s t e r i l e b a r le y o v a r ie s on s u s c e p t i b i l i t y
to C la v ic e p s p u r p u r e a ....................................................
27
ix
ABSTRACT
The s e r io u s n e s s o f e r g o t c a u s e d by C la v lc e p s p u r p u r e a ( F r . ) T u l.
i n m ale s t e r i l e b a r l e y and w h e a t h a s p ro m p ted f u r t h e r s tu d y o f th e
b io lo g y o f t h i s p a th o g e n . F o r e v a l u a t i o n o f v a r i o u s c o n t r o l m e a s u re s ,
a te c h n iq u e o f i n o c u l a t i o n was d e v e lo p e d and in v o lv e d t h e rem o v al o f
th e u p p e r 2 - 4 mm o f th e glum es p r i o r t o i n o c u l a t i o n w ith a c o n i d i a l
s u s p e n s io n u s in g an a t o m iz e r . U se o f t h i s te c h n iq u e r e s u l t e d i n n e a r ­
l y 1007. h e a d and f l o r e t i n f e c t i o n w h e re a s p r e v i o u s l y d e s c r ib e d m eth o d s
r e s u l t e d i n 20-607. h ead i n f e c t i o n . S tu d ie s on i n o c u l a t i o n d e n s i t y
r e v e a le d t h a t maximum i n f e c t i o n o c c u r r e d w ith 10$ o r m ore c o n i d ia p e r
m l. S tu d ie s o n d u r a t i o n o f i n f e c t i o n p e r i o d o f u n f e r t i l i z e d and
f e r t i l i z e d o v a r i e s i n d i c a t e d t h a t i n o c u l a t i o n d u r in g and s h o r t l y a f t e r
a n t h e s i s r e s u l t e d i n th e h i g h e s t l e v e l s o f f l o r e t i n f e c t i o n . W ith u n ­
f e r t i l i z e d f l o r e t s , s u s c e p t i b i l i t y d e c l i n e d a t 10 d a y s and was l o s t
c o m p le te ly 15 d a y s a f t e r th e i n i t i a t i o n o f a n t h e s i s . F e r t i l i z e d
o v a r i e s w ere s u s c e p t i b l e r i g h t a f t e r f e r t i l i z a t i o n . A f t e r th e o v a r i e s
had b e e n f e r t i l i z e d f o r 4 d a y s s u s c e p t i b i l i t y d e c r e a s e d u n t i l no i n ­
f e c t i o n o c c u r r e d 9 d a y s a f t e r f e r t i l i z a t i o n . Many c h e m ic a ls w ere
s c re e n e d f o r t h e i r e f f e c t i v e n e s s i n i n h i b i t i n g g e r m in a tio n and g ro w th
o f C. p u r p u r e a . Benomyl a t 10 ppm i n h i b i t e d g e r m in a tio n o f c o n i d ia
w h ile g ro w th was c o m p le te ly i n h i b i t e d a t 20 ppm. U nder f i e l d con­
d i t i o n s u s in g m ale s t e r i l e b a r l e y , 2400 ppm benom yl a p p l ie d t h r e e
tim e s j u s t p r i o r t o and d u r in g a n t h e s i s gave some c o n t r o l o f e r g o t .
To d e te rm in e why benom yl d id n o t g iv e c o m p le te c o n t r o l v a r i o u s co n ­
c e n t r a t i o n s o f benom yl w ere a p p l ie d to f l o r e t s w ith th e u p p e r p o r t i o n
o f t h e i r glum es rem oved w h ich h ad b e e n p r e v i o u s l y in o c u l a t e d w ith C.
p u r p u r e a . U sin g t h i s m e th o d , f l o r e t i n f e c t i o n was re d u c e d from 947. to
117. w ith 1000 ppm benom yl and t o 07. i f a w e tt in g a g e n t su c h a s T r i t o n
X-77 o r M u l t i f i l m B u f f e r X was u s e d a lo n g w ith 1000 ppm b en o m y l. T h is
i n d i c a t e d t h a t benom yl m u st r e a c h th e s u r f a c e o f th e o v a ry a t o r b e f o r e
i n f e c t i o n to b e e f f e c t i v e s i n c e benom yl d id n o t a c t a s a n e r a d i c a n t
a g a i n s t t h i s p a th o g e n . U nder n a t u r a l c o n d i tio n s t h i s w i l l b e v e r y
d i f f i c u l t t o a c h i e v e , b u t v a r i o u s m eth o d s o f a p p l i c a t i o n and d i f f e r e n t
f o r m u la tio n s o f benom yl may p ro v e t o b e e f f e c t i v e .
I n m a le s t e r i l e
w h e a t, i t was o b s e rv e d t h a t C h r is h a d some d e g r e e o f r e s i s t a n c e in
co m p a riso n to o t h e r v a r i e t i e s t e s t e d . W h ile n o n e o f th e c o n t r o l
m e a su re s t e s t e d was e f f e c t i v e b y i t s e l f , th e p o s s i b i l i t y e x i s t s t h a t
a c o m b in a tio n o f o n e o r m ore o f them m ig h t p ro v e to b e q u i t e e f f e c t i v e .
T h is w ould in c lu d e th e u s e o f r e s i s t a n t g erm p lasm ; th e u s e o f a
v a r i e t y t h a t p ro d u c e s t i l l e r s o v e r a s h o r t tim e p e r i o d ; th e u s e o f a
good p o l l i n a t o r v a r i e t y t o i n s u r e r a p i d and c o m p le te f e r t i l i z a t i o n ;
and th e u s e o f a s y s te m ic f u n g ic i d e t o p r o v id e p r o t e c t i o n d u r in g 1015 d a y s a f t e r a n t h e s i s when th e h o s t i s m o st s u s c e p t i b l e . The la c k
o f t h e n e c e s s a r y germ plasm a t p r e s e n t h in d e r s th e t e s t i n g o f th e s e
p o s s ib ilitie s .
INTRODUCTION
The s u b s t a n t i a l i n c r e a s e i n y i e l d s o f c o r n , sorghum and o t h e r
c r o p s , by u s e o f h y b r id v i g o r , h a s s ti m u l a t e d many s c i e n t i s t s to
p ro p o s e schem es f o r p r o d u c ti o n o f h y b r id b a r l e y and w h eat ( 4 8 , 5 7 ) .
H y b rid se e d i s p ro d u c e d by f o r c i n g c r o s s p o l l i n a t i o n b etw ee n th e two
d iffe re n t p a re n t lin e s .
The p r e v e n t io n o f s e l f p o l l i n a t i o n i s
a c c o m p lish e d b y h an d e m a s c u la tio n o r by u s e o f m ale s t e r i l i t y .
M ale
s t e r i l i t y may b e e i t h e r g e n e t i c o r c y to p la s m ic b u t to d a t e o n ly
g e n e t i c m ale s t e r i l i t y
i s known i n b a r l e y ( 2 7 , 2 8 ) .
One o f s e v e r a l
p r o c e d u r e s d e s c r ib e d by Ramage ( 4 8 ) f o r p r o d u c ti o n o f h y b r id b a r l e y
se e d by u s e o f b a la n c e d t e r t i a r y t r i s o m i c s (BTT) i s a s f o ll o w s .
BTT
a r e t e r t i a r y t r i s o m i c s w ith th e r e c e s s i v e a l l e l e on th e two n o rm al
chromosomes and a d o m in a n t a l l e l e o f a m a rk e r g en e c a r r i e d on e i t h e r
th e c e n tro m e re o r th e in t e r c h a n g e d segm ent o f th e e x t r a chrom osom e.
The BTT a r e s e l f f e r t i l e and w ould b e m a in ta in e d by s e l l i n g i n an
i s o l a t i o n b lo c k in w h ich b o th BTT and d i p l o i d p l a n t s a r e p ro d u c e d .
The BTT and t h e d i p l o i d s a r e s e p a r a t e d on th e b a s i s o f a m a rk e r g e n e ,
o fte n p la n t c o lo r.
c h a ra c te ris tic .
The BTT a r e u s e d f o r m a in te n a n c e o f th e BTT
The d i p l o i d s , w h ich a r e m ale s t e r i l e and s e r v e as
th e fe m a le p a r e n t s , w ould b e sown b e tw e e n p l a n t s t h a t a r e good p o l l i n ­
a t o r s and w ould th u s s e r v e a s t h e m ale p a r e n t s .
The r e s u l t i n g
s e e d s a r e th e h y b r id s e e d w h ich w ould th e n b e s o ld to th e g ro w e r.
20 to 507. i n c r e a s e in y i e l d i s f o r e s e e n from th e u s e o f a d o p te d
A
2
h y b r id s ( 5 5 ) .
C y to p la s m ic m a le s t e r i l i t y and m ore r e c e n t l y g e n e t i c
m ale s t e r i l i t y
in w h eat a r e b e in g d e v e lo p e d f o r h y b r id s e e d p r o d u c tio n
(2 3 ).
S in c e th e f l o r e t s o f m a le s t e r i l e l i n e s a r e o p en f o r a lo n g tim e ,
th e y a r e m ore s u s c e p t i b l e to f l o r a l d i s e a s e s ( 1 6 , 5 4 ) .
I n M o n tan a,
m ale s t e r i l e l i n e s o f w h eat and b a r l e y a r e e x tre m e ly s u s c e p t i b l e to
e r g o t p o s s i b l y b e c a u s e o f low te m p e r a tu r e s t h a t o c c u r d u r in g f lo w e r ­
in g th u s i n h i b i t i n g c r o s s - p o l l i n a t i o n .
As a r e s u l t o f th e s e low
t e m p e r a t u r e s , th e f lo w e r s re m a in o p e n f o r a lo n g p e r io d o f tim e .
F u t r e l l and W e b ste r (2 2 ) s t a t e t h a t many e n v iro n m e n ta l c o n d i tio n s
su ch a s h o t o r c o ld te m p e r a tu r e s o r i r r a d i a t i o n can c a u s e p o l l e n to
be n o n -fu n c tio n a l.
A ta n a s o f f ( 2 ) and B a rg e r ( 3 ) h a v e f u l l y re v ie w e d m o st a s p e c t s o f
e rg o t.
The d i s e a s e i s p e r p e t u a t e d th r o u g h s c l e r o t i a w h ich a r e v i a b l e
up to 2 y e a r s ( 2 ) .
Even b ro k e n and m oldy s c l e r o t i a can g e rm in a te
under fa v o ra b le c o n d itio n s .
T h is f a c t o r i s o f g r e a t s i g n i f i c a n c e in
th e i n t r o d u c t i o n o f e r g o t w ith s e e d a llo w in g i t s d is s e m i n a ti o n o v e r
lo n g d i s t a n c e s .
S c l e r o t i a l g e r m in a tio n , lo n g e v ity o f s c l e r o t i a , and
o t h e r r e l a t e d a s p e c t s h av e b e e n s t u d i e d b y v a r i o u s i n v e s t i g a t o r s ( 1 2 ,
13, 2 4 , 3 1 , 4 5 , 4 7 ) .
G e n e r a l ly , s c l e r o t i a g e r m in a te d u r in g th e
f lo w e r in g p e r io d o f s u s c e p t i b l e c r o p s .
The l a r g e r and h e a v i e r
s c l e r o t i a p ro d u c e up to 60 s t r o m a t i c h e a d s o v e r a lo n g p e r i o d o f tim e .
3
A sc o sp o re s a r e b e s t d is c h a r g e d a t 75-787. r e l a t i v e h u m id ity ( 5 ) .
A sc o sp o re s and c o n i d ia a r e d is s e m in a te d a b o u t 46-g92 m e te r s by a i r
c u rre n ts ( 3 ).
P rim a ry i n f e c t i o n ta k e s p la c e m a in ly w ith a s c o s p o r e s
d is s e m in a te d by a i r c u r r e n t s .
S e c o n d a ry i n f e c t i o n i s c a u se d m a in ly
by c o n i d ia t h a t a r e c a r r i e d on i n s e c t s , by w in d , o r i n honey dew
d r ip p i n g on lo w e r f l o r e t s o f an i n f e c t e d h ead o r n e ig h b o r in g h e a d s
(3 , 5 , 5 1 ).
A r t i f i c i a l i n o c u l a t i o n o f e r g o t h a s b e e n a c c o m p lish e d u s in g
s e v e r a l m e th o d s.
a p p a ra tu s .
B ek esy ( 3 6 ) u s e d a h o r s e draw n m u l t i p l e i n j e c t i n g
Heck ( 3 6 ) h an d m a n ip u la te d ry e f l o r e t s c a u s in g them to
open p r e m a tu r a l ly and th e n in o c u l a t e d them w ith an aq u eo u s c o n i d i a l
s u s p e n s io n u s in g an a t o m iz e r .
U s u a lly aq u eo u s c o n i d i a l s u s p e n s io n s
h av e b e e n u s e d f o r i n o c u l a t i o n ( 2 9 , 4 3 , 5 0 ) .
H ow ever, Lew is (3 6 )
u s e d a c o n i d i a l s u s p e n s io n c o n t a i n i n g s u c r o s e w h ich w o u ld , t h e r e f o r e ,
b e s i m i l a r to th e c o m p o s itio n o f ho n ey dew.
F o r l a r g e s c a l e p r o d u c tio n
o f e r g o t s c l e r o t i a c o n i d i a l s u s p e n s io n s h av e b e e n s p ra y e d from 2 -9
tim e s d u r in g th e tim e o f f lo w e r in g o f r y e ( 4 1 , 5 0 ) .
K ir c h h o f f (3 0 ) and C am pbell ( 6 ) h av e s tu d ie d th e i n f e c t i o n o f
f e r t i l e r y e and b a r l e y b y t h e e r g o t fu n g u s C la v ic e p s p u r p u r e a ( F r . )
T u l.
P e n e t r a t i o n o c c u r s w i t h i n 24 h o u rs n e a r th e b a s e o f th e o v u le .
C o n id ia and honey dew a r e p ro d u c e d w i t h i n 6 -8 d a y s a f t e r i n o c u l a t i o n
(6 , 4 6 ).
The i n f e c t i o n p e r i o d oh r y e a p p e a r s to l a s t from a n t h e s i s
4
to 15 d a y s a f t e r f e r t i l i z a t i o n ( 3 ) .
a n t h e s i s th ro u g h th e m ilk s ta g e ( 4 9 ) .
I n w h e a t, i n f e c t i o n can o c c u r from
Sorghum and c o m w ere n o t i n ­
f e c t e d w ith e r g o t a f t e r f e r t i l i z a t i o n h a d o c c u r r e d ( 2 1 ) .
C o n tr o l m e a su re s f o r e r g o t t h a t a r e p r e s e n t l y u s e d in c lu d e u s e
o f e r g o t - f r e e s e e d s , d eep p lo w in g to b u ry s c l e r o t i a , and c ro p r o t a t i o n .
I n a d d i t i o n , to e l i m i n a t e s o u r c e s o f s e c o n d a ry in o c u lu m , g r a s s e s
b o r d e r in g f i e l d s c a n b e mowed o r m a le ic h y d r a z id e c a n b e s p ra y e d t o
d e la y th e f lo w e r in g o f g r a s s e s ( 7 , 9 , 3 4 ) .
I n th e p a s t , c h e m ic a l c o n t r o l o f e r g o t h a s n o t b e e n s u c c e s s f u l .
R e c e n tly , h o w e v e r, r e p o r t s h a v e a p p e a re d on c h e m ic a ls t h a t a r e i n ­
h i b i t o r y t o C. p u r p u r e a .
L i n d e n d f e ls e r (3 8 ) r e p o r t e d t h a t th e a n t i ­
b i o t i c cin n a m y c in i n h i b i t s t h e g ro w th o f C. p u r p u r e a i n c u l t u r e .
M a r u z z e lla ( 4 2 ) r e p o r t e d t h a t s e v e r a l p erfu m e o i l s i n h i b i t C la v ic e p s .
I n g re e n h o u s e t r i a l s S u la im a n e t a l . ( 5 3 ) s p ra y e d 5 ppm o f th e a n t i ­
b i o t i c a u r e o f u n g in o n P e n n is e tu m ty p h o id eu m R ic h w h ich h ad b e e n in o c ­
u l a t e d tw ic e w ith C. m ic r o c e p h a la ( W a l l r .) T u l .
T h is t r e a tm e n t
re d u c e d i n f e c t i o n b y 36% com pared t o a c o n t r o l .
I n a f i e l d t e s t w ith
f e r t i l e b a r l e y T im ian ( 5 6 ) u s e d 5 s y s te m ic f u n g i c i d e s and fo u n d t h a t
none w ere e f f e c t i v e a g a i n s t C. p u r p u r e a .
I f th e f l o r e t s a r e c l o s e d a t th e tim e o f s p r a y in g , a s y s te m ic
f u n g ic i d e m ig h t p r o v id e b e t t e r c o n t r o l th a n a p r o t e c t i v e f u n g ic i d e
i f i t w ere t r a n s l o c a t e d t o th e b a s e o f t h e o v u le w here i n f e c t i o n
o ccu rs.
D elp and K lo p p in g ( 1 5 ) r e p o r t e d t h a t benom yl ( m e th y l- 1 -
5
b u ty lc a r b a m o y l) - 2 - b e n z im id a z o le c a rb a m a te ) i s a s y s te m ic f u n g i c i d e .
I t p r e v e n t s V e r t i c i l l i u m w i l t symptom e x p r e s s io n and c o n t r o l s s e v e r a l
o t h e r d i s e a s e s su c h a s pow dery m ild e w s , a p p le scab and b la c k s p o t o f
ro se s.
I n a d d i t i o n s e v e r a l r e p o r t s h av e a p p e a re d o n th e u s e o f
benom yl f o r c o n t r o l o f v a r io u s o t h e r d i s e a s e s o f f r u i t , f i e l d and
v e g e t a b le c r o p s , o r n a m e n ta l s , and t u r f g r a s s e s ( I , 4 , 1 1 , 1 4 , 1 7 ,
20, 33, 4 0 ).
E rw in ( 1 8 , 1 9 ) c o n c lu d e d t h a t benom yl o r i t s b r e a k down
p r o d u c t was s y s te m ic s i n c e i t re d u c e d t h e s e v e r i t y o f V e r t l c i l l i u m
w i l t o f c o t t o n ( G ossypium h ir s u tu m L .) when a p p l ie d t o s o i l p r i o r to
in o c u la tio n .
I t s s y s t e m i c i t y was f u r t h e r c o n firm e d by b io a s s a y o f
le a v e s and stem s e c t i o n s o f p l a n t s grown in th e t r e a t e d s o i l .
H a rd is o n (2 5 ) r e p o r t e d t h a t a w a te r s u s p e n s io n o f benom yl a p p l ie d to
s o i l aro u n d M erio n b l u e g r a s s ( P oa p r a t e n s i s L . ) p l a n t s c o n t r o l l e d
e r g o t and s e v e r a l o t h e r d i s e a s e s , b u t h e d id n o t m e n tio n th e co n ce n ­
t r a t i o n o f th e f u n g ic i d e u s e d and t o w h at e x t e n t i t c o n t r o l l e d e r g o t .
Clemons and S i s l e r (1 0 ) showed t h a t i n aq u eo u s s o l u t i o n benom yl b r e a k s
down r a p i d l y to b e z im id a z o l c a rb a m a te m e th y l e s t e r w h ich i s a l s o
t o x i c to t e s t o r g a n is m s .
Lyda and B u r n e t t ( 3 9 ) fo u n d t h a t benom yl
c o m p le te ly s u p p r e s s e d th e g ro w th o f P h y m ato tric h u m om nivorum ( S h e a r )
D uggar a t 1 4 .5 ppm.
H ow ever, benom yl a t f u n g i t o x i c l e v e l s d id n o t
i n h i b i t th e r e s p i r a t i o n o f g e r m in a tin g s c l e r o t i a .
6
R e s is ta n c e to e r g o t w ould p r o v id e th e b e s t c o n t r o l .
R e p o rts from
th e M i s s i s s i p p i A g r i c u l t u r a l E x p e rim e n ta l S t a t i o n (4 4 ) i n d i c a t e t h a t
r e s i s t a n c e t o e r g o t h a s b e e n fo u n d i n h y b r id s o f D a l l i s g r a s s
( P asp alu m d i l a t a t u m P o i r ) .
R e s is ta n c e t o e r g o t h a s a l s o b e e n found
i n th e germ plasm o f Sorghum v u lg a r e P e r s . ( 5 2 ) .
W h ile s e v e r a l c o n t r o l m e a su re s can b e u s e d f o r c o n t r o l o f e r g o t ,
none i s c o m p le te ly e f f e c t i v e .
Use o f e r g o t - f r e e s e e d c o u ld re d u c e
i n f e c t i o n b u t t h e r e may b e some s c l e r o t i a from a p r e v i o u s l y i n f e c t e d
c ro p t h a t c o u ld s e r v e a s in o c u lu m .
In o cu lu m c o u ld a l s o come from
i n f e c t e d g r a s s e s b o r d e r in g th e f i e l d .
A n o th e r c o n t r o l m e asu re w ould
b e to grow th e c ro p i n an a r e a w here d ev e lo p m e n t o f e r g o t i s r e s t r i c t ­
ed by e n v iro n m e n ta l c o n d i t i o n s .
F o r in s ta n c e , v e ry l i t t l e
o b s e rv e d i n A riz o n a on m ale s t e r i l e b a r l e y .
erg o t is
H ow ever, t r a n s p o r t a t i o n
o f h y b r id s e e d from a r e a s su c h a s A riz o n a t o M ontana w ould b e
e c o n o m ic a lly u n d e s i r a b l e .
T h e r e f o r e , i f h y b r id w h eat and b a r l e y a r e
to b e grown i n th e n o r t h e r n s t a t e s , th e s e e d w i l l a l s o h a v e t o b e
p ro d u c e d i n th e s e a r e a s .
U n f o r t u n a t e l y , e r g o t i s p r e v a l e n t i n th e
n o r t h e r n s t a t e s , th u s n e c e s s i t a t i n g i t s c o n t r o l th r o u g h u s e o f
c h e m ic a ls , c u l t u r a l p r a c t i c e s o r r e s i s t a n c e .
I n th e a b s e n c e o f
c o m p le te ly r e s i s t a n t germ p la s m , th e p r e v e n t io n o f i n f e c t i o n m ig h t
o f f e r some c o n t r o l .
W h ile p r o t e c t i v e f u n g ic i d e s h av e b e e n i n e f f e c t i v e
i n c o n t r o l l i n g e r g o t , t h e u s e o f an e f f e c t i v e s y s te m ic f u n g ic i d e
7
t h a t w ould r e a c h th e s i t e o f i n f e c t i o n i . e . , th e b a s e o f th e o v a r y ,
c o u ld o f f e r some hope f o r c h e m ic a l c o n t r o l .
C o n s id e r in g th e ab o v e p o i n t s and th e s e r i o u s n e s s o f e r g o t in
m ale s t e r i l e b a r l e y and w h e a t, th e f u r t h e r s tu d y o f th e b io lo g y o f
t h i s p a th o g e n was u n d e r ta k e n .
S in c e p r e v io u s work d id n o t in v o lv e
m ale s t e r i l e w h eat and b a r l e y a s h o s t s , s t u d i e s w ere c o n d u c te d on
i n o c u l a t i o n te c h n iq u e , i n f e c t i o n p e r i o d , r e s i s t a n c e , and c h e m ic a l
c o n tro l.
MATERIALS AND METHODS
P la n t m a te r ia ls . -
S eed o f t h e 2 row m ale s t e r i l e b a la n c e d
t e r t i a r y t r i s o m i c b a r l e y 67-C-383 BTT 2^ ms and Hypana and Compana
f e r t i l e b a r l e y s w ere s u p p lie d b y P r o f . R .F . E s l i c k (M ontana S t a t e
U n iv e rs ity ).
S eed o f m ale s t e r i l e w h eat v a r i e t i e s and e l i t e l i n e s
was s u p p lie d by D r. W. W. R o ath (D ek alb A g r i c u l t u r a l A s s o c i a t i o n ,
F a rg o , N o rth D a k o ta ).
S eed s w ere p l a n t e d i n san d y loam i n 1 7 .5 cm p l a s t i c p o t s , in
th e g re e n h o u s e .
S u p p le m e n ta l i l l u m i n a t i o n w ith in c a n d e s c e n t l i g h t s
was u s e d when n e c e s s a r y to in d u c e h e a d in g .
F i e l d t e s t s w ere co n ­
d u c te d on th e M ontana S t a t e U n i v e r s i t y Agronomy Farm n e a r Bozem an.
Rows 3 .5 m lo n g sp a c e d 30 cm a p a r t w ere u s e d .
F o u r row s o f m ale
s t e r i l e b a r l e y w ere a l t e r n a t e l y p l a n t e d b e tw e e n f o u r g u a rd row s o f
Hypana f e r t i l e b a r l e y .
S i m i l a r l y , f o u r row s o f th e w h eat m ale
s t e r i l e v a r i e t i e s w ere p l a n t e d b e tw e e n 4 row s o f f e r t i l e w h eat o r
b a rle y .
C u ltu re s . -
The c u l t u r e o f C. p u r p u r e a u s e d i n th e s e s t u d i e s was
i s o l a t e d from honey dew o f n a t u r a l l y i n f e c t e d m a le s t e r i l e b a r l e y .
I t was f u r t h e r m a in ta in e d on an ammonium c i t r a t e a g a r medium (ACD)
s l i g h t l y m o d if ie d from t h a t d e s c r i b e d b y K ybal e t a l ( 3 2 ) and
c o n s i s t e d o f th e f o llo w in g : C a to O ^ ^ ’ A H^O, 1 .4 4 g ; MgSO^*7 H^O, 0 .5 1
g ; K C l, 0 .1 2 5 g ; d i b a s i c ammonium c i t r a t e , 2 0 g ; S u c r o s e , 200 g ;
KHgPO^ m o n o b a sic , 0 .1 g ; a g a r , 12 g ; d i s t i l l e d w a te r t o I l i t e r .
In
9
some s t u d i e s a c a lc iu m n i t r a t e a g a r medium (CM) d e s c r ib e d b y McCrea
(4 3 ) was u s e d and c o n ta in e d th e f o llo w in g ; C a ^ O ^ ^ * ^ HgO, I g ;
KHgPO^ m o n o b a sic , 1 .2 5 g ; MgSO^*7 HgO, 0 .6 2 5 g ; M a lto s e , 30 g ; jag ar,
12 g ; w a te r , I l i t e r .
o f 2 4 -2 6 °C .
The c u l t u r e s w ere grown a t a room te m p e r a tu r e
U n le s s .o t h e r w i s e i n d i c a t e d , th e c o n i d ia from 10-12 day
o ld c u l t u r e s w ere u s e d .
C o n id ia w ere h a r v e s t e d by s h a k in g th e c u l t u r e s w ith w a te r .
The
c o n id ia -m y c e liu m s u s p e n s io n was th e n f i l t e r e d th r o u g h 6 l a y e r s o f
c h e e se c l o t h .
The c o h i d i a l c o n c e n t r a t i o n was d e te rm in e d w ith a
haemoc y to m e te r and f u r t h e r d i l u t e d w ith w a te r to th e d e s i r e d c o n i d i a l
c o n c e n tra tio n .
F o r s t u d i e s on c o n i d i a l g e r m in a tio n and g ro w th , th e
c o n i d ia w ere f u r t h e r w ashed b y a l t e r n a t e c e n t r i f u g a t i o n and r e s u s p e n ­
s io n in s t e r i l e d i s t i l l e d d e i o n iz e d w a te r .
C o n id ia w ere f i n a l l y
su sp en d ed i n 5 -1 0 ml o f s t e r i l e d i s t i l l e d d e io n iz e d w a te r by u s e o f
a lo o s e f i t t i n g hand h o m o g e n izer and d i l u t e d t o th e r e q u i r e d co n ce n ­
tra tio n .
A s e p tic te c h n iq u e was u s e d a t a l l ti m e s .
In o c u la tio n te c h n iq u e s . -
The f l o r e t s o f m ale s t e r i l e b a r l e y o p en
4 -5 d ay s a f t e r th e y em erge from th e b o o t .
f l o r e t s o p en w ere s e l e c t e d f o r i n o c u l a t i o n .
mm from th e to p w ith s c i s s o r s .
G e n e r a l ly , h e a d s w ith
The glum es w ere c u t 2 -4
An aq u eo u s c o n i d i a l s u s p e n s io n o f th e
d e s i r e d c o n c e n t r a t i o n was e i t h e r d ro p p e d i n t o th e o p e n f l o r e t s w ith a
c a p i l l a r y tu b e o r was s p ra y e d o n to t h e f l o r e t s w ith an a to m iz e r o r a
10
S u re -S h o t s p r a y e r m odel A (M ilw aukee S p r a y e r M fg. C o ., M ilw au k ee,
W is .).
I n o c u la te d h e a d s w ere u s u a l l y c o v e re d w ith g l a s s i n e b a g s
c l ip p e d t i g h t l y a t th e b a s e o f th e h e a d to m a in ta in h ig h h u m id ity and
a l s o to a v o id any o u t s i d e s o u r c e o f in o cu lu m o r c o n ta m in a tio n .
C o n id ia l g e r m i n a ti o n . -
S tu d ie s on c o n i d i a l g e r m in a tio n w ere
c o n d u c te d u s in g deep w e ll s l i d e s p r e v i o u s l y so ak ed in p o ta s s iu m d i ­
ch ro m ate g l a s s c l e a n in g s o l u t i o n f o r 12 h o u rs o r more and w ashed
th o ro u g h ly w ith d e t e r g e n t and r i n s e d w ith d e io n iz e d w a te r .
M o ist
cham bers w ere p r e p a r e d by c o v e r in g th e b o tto m o f 9 cm p e t r i d is h e s
w ith Whatman No. 4 f i l t e r p a p e r .
A f t e r s t e r i l i z a t i o n 4 ml o f s t e r i l e
w a te r w ere added t o e a c h p e t r i d i s h .
Two ml o f th e t e s t m a t e r i a l ,
I ml o f aq u eo u s c o n i d i a l s u s p e n s io n (3 0 -5 0 c o n i d ia p e r h ig h pow er
f i e l d ) and I ml o f e i t h e r 0.05M c i t r a t e p h o s p h a te b u f f e r o r 0.067M
p o ta s s iu m - p h o s p h a te b u f f e r o f d e s i r e d pH w ere m ixed th o r o u g h ly in
s t e r i l e t e s t tu b e s .
I f b u f f e r was o m m ited, th e t e s t m a t e r i a l and
c o n i d i a l s u s p e n s io n w ere m ix ed i n a 1 :1 r a t i o .
A d ro p o f th e m ix tu r e
was th e n p la c e d i n th e d eep w e ll s l i d e s and in c u b a te d a t room te m p e r­
a tu re .
A t l e a s t 250 s p o r e s w ere c o u n te d i n e a c h r e p l i c a t i o n .
O vary e x t r a c t s . -
A w eig h ed q u a n t i t y o f m ale s t e r i l e b a r l e y
o v a r i e s m inus t h e i r stam en s w ere b o i l e d 3 tim e s i n 807. e t h a n o l f o r 30
min and th e e x t r a c t s co m b in ed .
The com bined e x t r a c t s w ere re d u c e d in
11
volum e to 10 ml b y f l a s h e v a p o r a tio n and th e n d r i e d c o m p le te ly i n a
p r e v i o u s l y w eig h ed b e a k e r u n d e r a s tr e a m o f h o t a i r .
th e c ru d e e x t r a c t was d e te r m in e d .
d i s t i l l e d d e io n iz e d w a te r .
The w e ig h t o f
I t was th e n d i s s o l v e d in 20 ml o f
F iv e ml o f t h i s s o l u t i o n w ere k e p t a s a
c ru d e e x t r a c t w h ile th e r e m a in in g p o r t i o n was p a s s e d th r o u g h Dowex 1 8X (1 0 0 -2 0 0 m esh) fo rm a te form and Dowex 5 OX (1 0 0 -2 0 0 m esh) H+ form
io n ex ch an g e r e s i n s and t h e n e u t r a l f r a c t i o n c o l l e c t e d .
O rg a n ic a c i d s
w ere e l u t e d from th e Dowex I r e s i n w ith 6 N fo rm ic a c i d w h ile amino
a c i d s w ere e l u t e d from th e Dowex 50 r e s i n w ith 107. NH.0H.
4
T h ese
f r a c t i o n s w ere d r i e d i n p re w e ig h e d b e a k e r s u n d e r h o t a i r .
They w ere
th e n d i s s o l v e d i n d e i o n iz e d w a te r and p a s s e d th r o u g h s t e r i l i z e d
m e t r i c e l membrane f i l t e r s
( 0 .4 5 ti ) .
The f i l t r a t e s w ere k e p t a t - 2 0 ° C
u n til used.
O vary w a s h in g s . -
To d e te r m in e th e m a t e r i a l p r e s e n t on th e
e x t e r i o r o f o v a r i e s o f m ale s t e r i l e b a r l e y , 5 0 -8 0 o v a r i e s w ith o u t
stam en s w ere p la c e d i n 15 ml o f d i s t i l l e d d e i o n iz e d w a te r and sh ak en
f o r 30 min o n a w r is t- a r m s h a k e r .
The o v a r i e s w ere th e n rem oved and
th e w a sh in g s d r i e d i n a p re w e ig h e d b e a k e r u n d e r a s tre a m o f h o t a i r .
The p r o c e d u r e f o r f r a c t i o n a t i o n was th e same a s f o r t h e o v a ry e x t r a c t s .
Honey dew e x t r a c t . -
G e n e r a l l y , 6 d a y s a f t e r i n f e c t i o n w ith C.
p u r p u r e a , honey dew a p p e a r s on t h e s u r f a c e o f th e o v a r i e s .
T w enty-
12
t h r e e o v a r i e s w ith honey dew w ere sh a k e n in 0.85% NaCl to p r e v e n t
r u p t u r e o f th e c o n i d i a .
The c o n i d i a l s u s p e n s io n was th e n p a s s e d
th ro u g h 6 l a y e r s o f c h e e s e c l o t h .
and th e s p o re p e l l e t d i s c a r d e d .
The f i l t r a t e was c e n t r i f u g e d tw ic e ,
The s u p e r n a ta n t l i q u i d was th e n
f i l t e r e d th r o u g h Whatman No. I p a p e r to rem ove any r e m a in in g s p o r e s .
The f i l t r a t e was th e n e v a p o r a te d down to 10-12 ml u n d e r a h o t a i r
s tr e a m .
The p r o c e d u r e f o r f r a c t i o n a t i o n was th e same a s f o r th e o v a ry
e x tra c t.
C h ro m ato g rap h y . -
D esc e n d in g p a p e r c h ro m a to g ra p h y was u s e d i n th e
a n a l y s i s o f th e c o n s t i t u e n t s o f th e n e u t r a l f r a c t i o n o f o v a ry w ash­
i n g s , o v a ry e x t r a c t s , and ho n ey dew e x t r a c t s .
A liq u o ts ( 5 - 1 0 p i ) o f
e a c h s o l u t i o n w ere s p o t t e d on Whatman No. 1 p a p e r .
The f o llo w in g
s o l v e n t s w ere u s e d to d e v e lo p th e c h ro m a to g ram s: S o lv e n t (A) n - b u t a n o l :
a c e t i c a c i d : w a te r ( 4 : 2 : 1 ,
v , v , v ) o r (B ) ( 4 : 1 : 5 ,
a c e t a t e : p y r i d i n e : w a te r ( 8 : 2 : 1 ,
w a te r ( 1 4 : 2 : 4 ,
8 0 :1 0
v , v , v ) ; (C ) E th y l
v , v , v ) ; (D) I s o p r o p a n o l: n - b u t a n o l :
v , v , v ) ; (E ) P h e n o l: w a te r (807. l i q u i d p h e n o l: w a te r ,
v ,v ).
C h e m ic a ls . -
The s y s te m ic f u n g ic i d e benom yl ( = S e n l a t e K m e t h y l - I -
( b u ty lc a r b a m o y l) - 2 - b e n z im id a z o le c a rb a m a te ) was s u p p lie d a s t e c h n i c a l
m a t e r i a l o r a s a 507. w et ta b I e pow der b y E . I . du P o n t de Nemours and
C o ., I n c . , W ilm in g to n , D e l.
Nabam (= D ith a n e A 4 0 ) (D iso d iu m e t h y l e n e -
13
b i s d i t h i o c a r b a m a t e , 93% a c t i v e i n g r e d i e n t ) and D ith a n e M 45
(M anganese++ 16%, Z in c ++ 2% and E th y le n e b is d i t h i o c a r b a m a t e io n 62%)
w ere s u p p lie d b y Rohm and H aas C o ., P h i l a d e l p h i a , P a .
The o t h e r
c h e m ic a ls u s e d w e re : E t h ir im o l ( 5 - b u ty l - 2 - e th y la m in o - 6 - h y d r o x y - 4 meth y ! p y r i m id i n e ) 80% a c t i v e i n g r e d i e n t o f P l a n t P r o t e c t i o n L td .
S u r r e y , E n g la n d ; F 849 ( 2 - a m i n o - 4 - m e t h y l - 5 - t h i a z o l e c a r b o x a n i l i d e ) and
G 696 ( 2 , 4 -d im e t h y l - 5 - t h i a z o l e c a r b o x a n i l i d e ) o f U n ir o y a l C hem ical C o .,
B e th a n y , C o n n .; B ay er 33172 ( 2 - ( 2 - f u r y l ) - b e n z i m i d a z o l e ) 977. a c t i v e
i n g r e d i e n t o f Chemagro C o r p o r a ti o n , K ansas C i t y , M o .; C ap tan (Nt r i c h l o r o m e th y l m er cap t o - 4 - c y lo h e x e n e - 1 ,2 , d ic a r b o x im id e ) 507. w et ta b I e
pow der o f S t a u f f e r Chem. C o ., San F r a n c i s c o , C a l i f . ; T h ia b e n d a z o le
(TBZ) [ 2 - ( 4 - t h i a z o l y l ) b e n z im id a z o le ] 607. a c t i v e i n g r e d i e n t o f
M erck C hem ical D i v i s i o n , Rahway, N .J .
The e m u l s i f t a b l e m i n e r a l o i l s L S -1 1 9 5 , L S -0 9 2 5 , LS-1183 and LS1197 w ere s u p p lie d b y A m erican O il C o ., W h itin g , I n d ia n a .
O rch ex 792
and O rchex 796 w ere s u p p lie d b y E sso R e s e a rc h and E n g in e e r in g C o .,
A g r i c u l t u r a l P r o d u c ts L a b . , L in d e n , N .J .
The p erfu m e o i l s B o u q u et
No. 2 2 , B o u q u et No. 8 2 1 , P alm a B o u q u e t, B lu e S to n e B o u q u et w ith
t r a d e m ark MM&R w ere s u p p lie d b y M agnus, MaBee and R ey n ard D iv is io n
o f BFM C o r p o r a tio n , P a ra m u s, N .J .
The i n s e c t i c i d e d la z in o n AG 500 ( o - o - d i e t h y l - o - ( 2 - i s o p r o p y l - 4 m e th y l- 6 - p y r i m i d i n y l ) p h o s p h o f o th ia le 48%, x y le n e 367.) was s u p p lie d
14
b y G eigy C hem ical C o ., A r d s l e y , N.Y.
P o is o n fo o d t e s t s . -
Benomyl was su sp e n d ed i n I ml a c e to n e to
w hich w a te r was ad d ed to make t h e f i n a l c o n c e n t r a t i o n o f benom yl 20
tim e s t h a t r e q u i r e d i n th e g ro w th medium .
w ere su sp e n d e d i n w a t e r .
Nabam and D ith a n e M 45
One ml o f e a c h c o n c e n t r a t i o n o f th e f u n g i­
c id e was th e n p i p e t t e d i n t o 20 ml o f warm m e lte d ACD a g a r , s h a k e n ,
and p o u re d im m e d ia te ly i n t o p e t r i d i s h e s .
A f t e r s o l i d i f i c a t i o n th e y
w ere i n o c u la te d w ith a 0 .9 mm m y c e lia l d i s c o f a 10 o r 12 d ay o ld
c u l t u r e o f C. p u r p u r e a g ro w in g on ACD a g a r .
a p p r o p r i a t e am ount o f w a te r o r a c e to n e .
C o n tr o ls r e c e iv e d th e
The c u l t u r e s w ere m a in ta in e d
a t room te m p e r a tu r e f o r 1 5 -2 0 d a y s and th e g ro w th m e asu re d fro m th e
c e n t e r o f th e in o c u lu m d i s c .
The t o x i c i t y o f th e f u n g i c i d e s , p erfu m e
o i l s , and m in e r a l o i l s was a l s o t e s t e d a s f o l l o w s .
A c o n id ia l
s u s p e n s io n o f C. p u r p u r e a was s p ra y e d on s o l i d i f i e d ACD a g a r o r CM
ag ar.
Then a s t e r i l i z e d f i l t e r p a p e r d i s c ( D if c o L a b o r a t o r i e s ) 7 mm
i n d ia m e te r s a t u r a t e d w ith v a r i o u s c o n c e n t r a t i o n s o f th e t e s t m a t e r i a l
su sp e n d ed i n w a te r o r a c e to n e , was p la c e d o n th e in o c u l a t e d m e d ia .
O b s e r v a tio n s on th e i n h i b i t i o n o f g ro w th a ro u n d th e d i s c w ere ta k e n
a f t e r 2 5 -3 0 d a y s i n c u b a tio n a t room te m p e r a t u r e .
The e f f e c t o f benom yl and D ith a n e M 45 on g ro w th o f C. p u r p u r e a
was a l s o d e te rm in e d by m e a s u rin g t h e i r e f f e c t on m y c e lia l d r y w e ig h t.
When th e te m p e r a tu r e o f s t e r i l i z e d ACD medium w ith o u t a g a r was a b o u t
15
4 0 -4 3 °C , 2 .5 ml o f th e a p p r o p r i a t e c o n c e n t r a t i o n o f t e s t m a t e r i a l p lu s
2 ml o f a t h i c k c o n i d i a l s u s p e n s io n w ere added t o 25 ml o f m e d ia .
T hese f l a s k s w ere k e p t s t a t i o n a r y a t room te m p e r a tu r e f o r 1 4 -2 0 d a y s .
The m y c e lia l m at was f i l t e r e d on Whatman No. 4 p a p e r , d r i e d o v e r n ig h t
a t IOO0 C1 and w e ig h e d .
B io a s s a y o f b en o m y l. -
R e s id u e s o f benom yl o r i t s b r e a k down
p r o d u c t w ere b io a s s a y e d i n p l a n t p a r t s u s in g P e n i c l l l l u m expansum
Lk. ex Thom, in th e same m anner a s d e s c r ib e d b y E rw in e t a l ( 1 9 ) .
RESULTS
I n o c u l a t i o n te c h n i q u e . -
As a b a s i s f o r s t u d i e s on c h e m ic a l
c o n t r o l and r e s i s t a n c e i t was n e c e s s a r y to d e v e lo p a m ethod o f in o c u l ­
a t i o n t h a t w ould r e s u l t i n maximum p e r c e n t i n f e c t i o n .
I n g re e n h o u s e
t e s t s when m ale s t e r i l e b a r l e y p l a n t s w ith f l o r e t s k e p t o p en by
v a r io u s m e th o d s , su c h a s p l a c i n g th e p l a n t s i n h u m id ity c h a m b e rs, w ere
in o c u la te d by s p r a y in g a c o n i d i a l s u s p e n s io n o n th e h e a d s , a low
i n f e c t i o n p e r c e n ta g e r e s u l t e d .
H ow ever, i f th e u p p e r 2 - 4 mm o f th e
glum es was rem oved f o llo w e d b y i n o c u l a t i o n u s in g an a to m iz e r o r
c a p i l l a r y t u b e , n e a r l y 100 p e r c e n t o f th e f l o r e t s w ere i n f e c t e d .
The
r e s u l t s shown i n T a b le I i n d i c a t e t h a t maximum i n f e c t i o n was o b ta in e d
u s in g an a to m iz e r to a p p ly t h e in o c u lu m .
I n a d d i t i o n , i f o n ly th e
awns w ere rem oved ( F i g . I ) , th e i n f e c t i o n p e r c e n ta g e was lo w e r and
q u i t e v a r i a b l e s in c e t h e f l o r e t s o p en a t d i f f e r e n t tim e s on o n e h e a d .
I n f i e l d t r i a l s , 80-967. o f m ale s t e r i l e b a r l e y f l o r e t s w ith glum es
c l ip p e d b a c k w ere i n f e c t e d when i n o c u l a t e d o n c e w ith a c a p i l l a r y tu b e
and b a g g e d .
H ow ever, i f th e f l o r e t s w ere n o t c l ip p e d b a c k and n o t
b ag g ed a f t e r b e in g i n o c u l a t e d t h r e e tim e s u s in g an a to m iz e r o r S u re
S h o t s p r a y e r , 70-757. o f t h e f l o r e t s becam e i n f e c t e d .
In o cu lu m d e n s i t y . -
The e f f e c t o f in o c u lu m d e n s i t y on i n f e c t i o n
was s t u d i e d so t h a t a s ta n d a r d in o c u lu m c o u ld b e u s e d i n s t u d i e s on
re s is ta n c e .
F l o r e t s o f g re e n h o u s e grown m ale s t e r i l e b a r l e y and
M exican S t e r i l e No. 2 w h e a t w ith glum es c l ip p e d b a c k w ere in o c u l a t e d
17
TABLE I .
A c o m p a riso n o f m eth o d s o f i n o c u l a t i o n o f C la v ic e p s
p u r p u r e a o n i n f e c t i o n o f f l o r e t s o f g re e n h o u s e grown
m ale s t e r i l e b a r l e y .
F lo r e t p re p a ra tio n
H
H
I.
sJ
U pper 2 - 4 mm
o f glum es
rem oved.
Awns o n ly
rem oved.
a/
M ethod o f i n o c u l a t i o n —
7. F l o r e t s i n f e c t e d
I.
C a p illa ry
80
2.
A to m iz e r
93
I.
C a p illa ry
81
2.
A to m iz e r
83
A c o n i d i a l s u s p e n s io n o f IO^ c o n i d i a p e r m l was u s e d
18
F ig u r e I .
M ale s t e r i l e b a r l e y h e a d s show ing th e d e g r e e o f glum es
m o d ific a tio n used in in o c u la tio n s tu d ie s .
A.
Norm al
B.
Awns o n ly rem oved.
C.
U pper 2 - 4 mm o f glum es rem oved.
19
20
u s in g a c a p i l l a r y t u b e .
p la c e d i n e a c h f l o r e t .
A bout 2 0 -3 0 p i o f a c o n i d i a l s u s p e n s io n w ere
I n f e c t i o n c o u ld ta k e p l a c e w ith a s few a s 10
c o n i d ia p e r ml on b a r l e y and 1000 c o n i d ia p e r ml i n w h eat b u t maximum
i n f e c t i o n o c c u r r e d when 10"* o r m ore c o n i d ia p e r ml w ere u s e d ( F i g . 2 ) .
C o n s id e rin g t h a t an a v e r a g e o f 25 p i o f in o c u lu m was a p p l ie d to ea c h
b a r l e y f l o r e t , i t a p p e a r s t h a t o n e c o n id iu m c a n p r o b a b ly i n i t i a t e
i n f e c t i o n , w ith maximum i n f e c t i o n o c c u r r i n g when 2500 o r more c o n i d ia
p er f lo r e t are u sed .
S u s p e n s io n o f t h e c o n i d ia i n 27. s u c r o s e r a t h e r
th a n i n w a te r d id n o t i n c r e a s e th e i n f e c t i o n p e r c e n ta g e in b a r l e y .
O c c a s io n a lly i n f e c t i o n o c c u r r e d w ith no honey dew o r s c l e r o t i a l
d e v e lo p m e n t.
Such o v a r i e s w ere o b s e r v e d m i c r o s c o p ic a lly and many
more c o n i d ia w ere fo u n d th a n h ad b e e n u s e d f o r i n o c u l a t i o n .
M oreover
su ch o v a r i e s w ere s h ru n k e n and d i s c o l o r e d a s com pared to h e a l t h y o n e s .
F u r th e r ,
some s c l e r o t i a w ere so m in u te t h a t th e y w ere n o t v i s i b l e
u n t i l f l o r e t s w ere d i s s e c t e d .
T h e re fo re , a l l th e f l o r e t in f e c tio n
p e r c e n ta g e s in c lu d e t h e s e i n f e c t e d sh ru n k e n o v a r i e s and m in u te
s c le ro tia .
In fe c tio n p e rio d . -
To d e te r m in e th e l e n g t h o f t h e s u s c e p t i b i l i t y
p e r io d o f f i e l d grown u n f e r t i l i z e d m a le s t e r i l e b a r l e y f l o r e t s ,
i n o c u l a t i o n s w ere made from 5 d a y s p r i o r to a n t h e s i s t o 25 d a y s a f t e r
a n th e s is .
An aq u eo u s c o n i d i a l s u s p e n s io n (1 0 ^ c o n i d ia /m l) was a to m iz ­
ed o n to f l o r e t s w ith glum es c l ip p e d b a c k w h ich h ad b e e n p r e v i o u s l y
21
F ig u re 2
The e f f e c t o f in o cu lu m d e n s i t y o f C la v ic e p s p u r p u r e a on
i n f e c t i o n o f n o n - f e r t i l i z e d f l o r e t s o f m ale s t e r i l e
b a r l e y and w h e a t.
BARLEY
/WHEAT
PER CENT FLORETS
INFECTED
22
LOG
CONIDIAL
IO
CONCENTRATION
23
b agged to p r e v e n t i n f e c t i o n and f e r t i l i z a t i o n .
The r e s u l t s shown in
F ig u r e 3 i n d i c a t e t h a t u n f e r t i l i z e d o v a r i e s w ere m o st s u s c e p t i b l e from
5 d ay s p r i o r to a n t h e s i s t o 5 d a y s a f t e r a n t h e s i s .
S u s c e p tib ility
d e c l in e d a t 10 d ay s and was l o s t c o m p le te ly a f t e r 15 d a y s .
Some i n v e s t i g a t o r s h a v e s u g g e s te d t h a t f e r t i l i z e d o v a r i e s a r e
r e s i s t a n t to i n f e c t i o n ( 2 2 ) .
I f t h i s w ere t r u e , c o n t r o l o f e r g o t
in m ale s t e r i l e b a r l e y and w h e a t c o u ld b e a c c o m p lish e d i f r a p i d
p o llin a tio n o ccu rred .
To d e te r m in e i f f e r t i l i z a t i o n o f t h e o v a ry
c o n f e r s r e s i s t a n c e to i n f e c t i o n b y C. p u r p u r e a , a t e s t was s e t up
u s in g f i e l d grown m ale s t e r i l e b a r l e y i n w h ich f l o r e t s w ere in o c u la te d
a t v a r i o u s tim e s a f t e r th e y h ad b e e n hand p o l l i n a t e d .
em erg in g from th e b o o t w ere b a g g e d .
H eads j u s t
F o u r d a y s l a t e r , th e glum es w ere
c l ip p e d b a c k and a m a tu re stam en from Hypana f e r t i l e b a r l e y was p la c e d
in ea c h f l o r e t and th e h e a d s b a g g e d .
D a ily , up t o 10 d a y s a f t e r
p o l l i n a t i o n , th e f l o r e t s w ere in o c u l a t e d a s d e s c r ib e d f o r u n f e r t i l i z e d
o v a rie s .
A t th e tim e o f i n o c u l a t i o n , th e p e r c e n ta g e o f th e o v a r i e s
t h a t h a d b e e n f e r t i l i z e d was d e te r m in e d , i f p o s s i b l e .
H ow ever, p r i o r
to th e 5 t h d ay a f t e r f e r t i l i z a t i o n , i t was im p o s s ib le t o t e l l i f an
o v a ry had b e e n f e r t i l i z e d .
T h e r e f o r e , th e p e r c e n ta g e o f f e r t i l i z e d
o v a r i e s f o r th e f i r s t 4 d a y s was c a l c u l a t e d on th e b a s i s o f th e
minimum p e r c e n ta g e o f f e r t i l i z e d o v a r i e s o b s e r v e d l a t e r .
From th e
r e s u l t s shown i n F ig u r e 4 i t a p p e a r s t h a t f e r t i l i z e d o v a r i e s w ere
24
F ig u r e 3 .
The r e l a t i o n o f a n t h e s i s o f u n f e r t i l i z e d f l o r e t s o f
m ale s t e r i l e b a r l e y to s u s c e p t i b i l i t y to C la v ic e p s
p u rp u re a .
DAYS
26
F ig u r e 4 .
The e f f e c t o f f e r t i l i z a t i o n o f m a le s t e r i l e b a r l e y
o v a r i e s on s u s c e p t i b i l i t y to C la v ic e p s p u r p u r e a .
TOTAL
FLORETS
(hypothetical)
( observed)
\
A-
TIME INOC. AFTER FERT.
(DAYS)
28
v e ry s u s c e p t i b l e r i g h t a f t e r f e r t i l i z a t i o n .
F o llo w in g th e f o u r t h d a y ,
s u s c e p t i b i l i t y d e c r e a s e d u n t i l no i n f e c t i o n o c c u r r e d 9 d a y s a f t e r
fe rtiliz a tio n .
V a rie ta l r e a c tio n . -
To d e te r m in e i f t h e r e a r e d e g r e e s o f
s u s c e p t i b i l i t y i n f e r t i l e b a r l e y v a r i e t i e s and i n w h eat m a le s t e r i l e
l i n e s and v a r i e t i e s , p l a n t s w ere in o c u l a t e d w ith a c o n i d i a l s u s p e n s io n
(10^ c o n i d ia /m l) a p p l ie d w ith a c a p i l l a r y t u b e .
The d a t a i n T a b le I I
i n d i c a t e t h a t th e f e r t i l e b a r l e y v a r i e t i e s H ypana and Compana w ere
e q u a l ly s u s c e p t i b l e ev en th o u g h Hypana had a s l i g h t l y h ig h e r d e g r e e
of s te rility .
I t a l s o shows t h a t f e r t i l i z e d o v a r i e s w ere i n f e c t e d
s in c e t h e p e r c e n t o f i n f e c t i o n was h ig h e r th a n p e r c e n t o f s t e r i l i t y .
S i m i l a r l y i n g re e n h o u s e t e s t s w h e a t m ale s t e r i l e e l i t e l i n e s w ere
i n o c u la te d a s a b o v e .
th a n A 3 0 4 8 .
As s e e n i n T a b le I I I , A 3032 was m ore s u s c e p t i b l e
I n f i e l d t e s t s , when th e p e r c e n t o f h e a d s c o n t a in in g
a t l e a s t o n e e r g o t s c l e r o t i u m w ere d e te r m in e d , th e m ale s t e r i l e w h eat
v a r i e t y C h r is a p p e a re d to b e l e s s s u s c e p t i b l e th a n P em bina o r M exican
S t e r i l e I (T a b le IV ) .
A lso J u s t i n a p p e a re d t o b e l e s s s u s c e p t i b l e
th a n S e l k i r k o r M exican S t e r i l e 2 .
H ow ever, t h e r e was a l i t t l e
d i f f e r e n c e b e tw e e n t h e v a r i e t i e s when th e p e r c e n t o f f l o r e t s i n f e c t e d
was d e te rm in e d on th e b a s i s o f h e a d s c o n t a in in g a t l e a s t o n e s c l e r ­
o tiu m .
To d e te r m in e i f th e d i f f e r e n c e i n p e r c e n t h e a d s i n f e c t e d was
due to s o m a tic r e s i s t a n c e , t h e s e m a le s t e r i l e w h eat v a r i e t i e s w ere
29
TABLE T I .
F e r t i l e b a r l e y s t e r i l i t y and s u s c e p t i b i l i t y to e r g o t .
V a r ie t y
7. S t e r i l i t y
—
7. F l o r e t s i n f e c t i o n
Hypana
19
44
Compana
12
43
—
N o n - in o c u la te d f l o r e t s .
—^
F l o r e t s o f g re e n h o u s e grow n p l a n t s in o c u l a t e d w ith a c o n i d i a l
s u s p e n s io n (10& c o n i d i a / m l ) .
30
TABLE I I I .
E lite lin e
S t e r i l i t y and s u s c e p t i b i l i t y o f e l i t e l i n e s o f m ale
s t e r i l e w h eat to e r g o t .
7. S t e r i l i t y
—
7. F l o r e t s i n f e c t i o n —^
A 3048
100
30
A 3032
99
43
—^
N o n - in o c u la te d f l o r e t s .
—^
F l o r e t s o f g re e n h o u s e grow n p l a n t s i n o c u la te d w ith a c o n i d i a l
s u s p e n s io n (1 0 ° c o n i d i a / m l ) .
31
TABLE IV .
D eg ree o f s u s c e p t i b i l i t y o f m a le s t e r i l e w h eat
v a r i e t i e s to e r g o t .
7. H eads
.
in fe c te d —
V a r ie t y
T o ta l
f l o r e t s in
in fe c te d
heads
% F lo re ts
in fe c te d
7. F l o r e t s
w ith
g ra in
M exican ~
S te rile I
71
897
18
11
fl/
Pem bina —
47
876
23
7
C h ris
33
837
17
8
M exican —^
S te rile 2
86
1287
22
I
S e lk irk
63
843
22
3
51
882
19
3
—
- 1
J u s t i n —^
a/
Grown b e tw e e n f e r t i l e Lemhi w h e a t.
W
Grown b e tw e e n f e r t i l e H ypana b a r l e y .
sJ
I n o c u la te d two tim e s w ith a c o n i d i a l s u s p e n s io n (1 0 ^ c o n i d ia /m l)
w ith a b a c k p a c k s p r a y e r .
32
t e s t e d i n th e g r e e n h o u s e .
I n d i v i d u a l f l o r e t s w ith glum es c l i p p e d b a c k
w ere in o c u l a t e d u s in g a c a p i l l a r y t u b e .
A l l o f th e v a r i e t i e s w ere
q u i t e s u s c e p t i b l e b u t C h r is was th e l e a s t s u s c e p t i b l e ( T a b le V ).
The
o b s e r v a ti o n s o f t h e v a r i e t y J u s t i n w ere o m itte d b e c a u s e o f a h ig h
d e g re e o f f e r t i l i t y .
C o n id ia l g e r m i n a ti o n . -
To d e te r m in e th e s o u rc e o f c a rb o n on th e
o v a ry s u r f a c e t h a t w ould s u p p o r t g e r m in a tio n o f C la v ic e p s c o n i d i a ,
o v a r i e s from m ale s t e r i l e b a r l e y p l a n t s w ere w ashed w ith w a te r .
An
e t h a n o l e x t r a c t o f o v a r i e s and w a te r e x t r a c t o f ho n ey dew w ere a l s o
te s te d .
G lu c o s e , f r u c t o s e , s u c r o s e and an u n i d e n t i f i e d compound w ere
fo und i n th e e t h a n o l i c o v a ry e x t r a c t ( T a b le V I ) .
O vary w a sh in g s
c o n ta in e d t h e same s u g a r s a s t h e e t h a n o l i c o v a r y e x t r a c t b u t th e w a te r
e x t r a c t o f honey dew c o n t a in e d o n ly g lu c o s e an d f r u c t o s e .
The unknown
compound i n t h e p e t h a n o l i c o v a r y e x t r a c t was e l u t e d fro m Whatman No. 4
p a p e r and th e n h y d r o ly s e d 20 and 4 0 m in i n I N HCl i n a b o i l i n g w a te r
b a th .
The h y d r o l y s a t e was re d u c e d i n volum e and th e n ch ro m ato g ra p h e d
on Whatman No. I p a p e r i n s o l v e n t s y ste m C.
One o f th e p r o d u c ts o f
h y d r o l y s i s was g lu c o s e p l u s a n u n i d e n t i f i e d com pound.
The unknown
was n o t i d e n t i f i e d b u t i t was e s t a b l i s h e d n o t t o b e c e l l o b i o s e ,
t r e h a l o s e , m e lib i o s e o r i s o m a l t o s e .
The e f f e c t o f th e c a t i o n , a n i o n , an d n e u t r a l f r a c t i o n s o f th e
o v a ry e x t r a c t o n c o n i d i a l g e r m in a tio n i s shown i n T a b le V I I .
B o th
33
TABLE V.
Susceptibility of greenhouse grown male sterile wheat
varieties to ergot.
Number
o f flo re ts
exam ined
Number
o f in fe c t­
ed f l o r e t s
C h ris
192
96
50
M exican
S te rile I
224
116
56
M an ito u
166
101
61
Pem bina
236
166
70
S e lk irk
210
157
75
M exican
S te rile 2
182
142
78
V a rie tie s
a/
7. F l o r e t s
,
in f e c tio n —
Glumes c l ip p e d b a c k and i n o c u l a t e d w ith c o n i d i a l s u s p e n s io n
(IO 6 c o n i d i a / m l ) .
34
TABLE V I.
Rg v a l u e s o f some a u t h e n t i c s u g a r s r e l a t i v e t o th o s e
from o v a r y e x t r a c t
S o lv e n t sy ste m
A
B
C
D
E
1 .0 0
1 .0 0
1 .0 0
1 .0 0
1 .0 0
Unknown I
.9 9
1 .0 0
.9 6
.9 9
.9 8
F r u c to s e
1 .0 8
1 .2 0
1 .4 5
1 .0 8
1 .7 8
Unknown 2
1 .0 7
1 .3 0
1 .4 1
1 .0 6
1 .7 5
S u c ro s e
.8 3
.5 0
.3 7
.8 1
1 .1 5
Unknown 3
.8 4
.5 0
.3 6
.8 0
——
.0 6
.2 0
---——
Compounds
G lu co se
I s o m a lto s e a
I s o m a lto s e b
——
.2 0
.4 0
I s o m a lto s e c
————
.4 0
1 .0 0
— —
I s o m a lto s e d
——
1 .0 0
——
- —* —
———
.1 3
.6 9
——
1 .5 0
1 .1 2
1 .3 5
——
.0 1
——
——
.9 8
————
.8 0
——
— ——
M e lib io s e
——
------
C e llo b io s e
———“
T r e h a lo s e
.7 7
D Mannose
1 .0 6
D G a la c to s e a
D G a la c to s e b
Unknown 4
.6 9
——
——- —
.3 0
——
——
.4 2
.8 1
——
.5 1
.5 4
.1 6
.4 6
.3 8
35
TABLE V I I .
E f f e c t o f m a le s t e r i l e b a r l e y o v a r y e t h a n o l l c e x t r a c t
f r a c t i o n s on t h e g e r m in a tio n o f c o n i d ia o f C la v ic e p s
p u rp u rea.
T re a tm e n ts
7. G e rm in a tio n
C rude e t h a n o l l c e x t r a c t
51
N e u tr a l f r a c t i o n
14
A nion f r a c t i o n
11
C a tio n f r a c t i o n
N e u tr a l + a n io n f r a c t i o n ( I : I )
3
20
A nion + c a t i o n f r a c t i o n ( 1 : 1 )
3
N e u tr a l + c a t i o n f r a c t i o n ( 1 : 1 )
9
N e u tr a l + a n io n + c a t i o n f r a c t i o n ( 1 : 1 : 1 )
H2 O
a/
—
24
I
G e rm in a tio n d e te rm in e d a f t e r 30 h r s i n c u b a tio n a t room te m p e r­
a t u r e s , T h re e r e p l i c a t i o n s p e r t r e a t m e n t . The f r a c t i o n s w ere
u n b u f f e r e d b u t th e pH was b e tw e e n 5 and 6 .
—
36
th e a n io n and th e n e u t r a l f r a c t i o n s s u p p o r te d b e t t e r g e r m in a tio n th a n
d id th e c a t i o n f r a c t i o n o r w a te r .
A c o m b in a tio n o f th e n e u t r a l
f r a c t i o n w ith e i t h e r th e c a t i o n o r a n io n f r a c t i o n o r b o th a l s o
s u p p o rte d b e t t e r g e r m in a tio n th a n w a te r .
H ow ever, t h e r e was some
i n d i c a t i o n t h a t t h e r e was an i n h i b i t o r y e f f e c t from th e c a t i o n
fra c tio n .
I t s c o m b in a tio n w ith e i t h e r t h e a n io n o r t h e n e u t r a l
f r a c t i o n re d u c e d th e g e r m in a tio n from t h a t i n t h e s e f r a c t i o n s a l o n e .
A c o m b in a tio n o f a l l t h r e e f r a c t i o n s s u p p o r te d th e b e s t g e r m in a tio n
e x c lu d in g t h a t i n t h e c ru d e e x t r a c t .
The pH o f b a r l e y o v a r i e s was t e s t e d by s q u a s h in g them o n H y d rio n
pH p a p e r and b y t e s t i n g th e pH o f th e w a te r i n w h ich o v a r i e s w ere
p la c e d and sh a k e n f o r 30 m in .
The pH was a b o u t 5 .4 i n b o th t e s t s .
The pH o f w a te r b e f o r e u s e was 6 . 5 .
The e f f e c t o f th e s u g a r form ed
o n th e s u r f a c e o f o v a r i e s o n c o n i d i a l g e r m in a tio n a t v a r i o u s pH’ s
was th e n t e s t e d .
As s e e n i n T a b le V I I I th e p e r c e n ta g e o f c o n i d i a l
g e rm in a tio n a t pH 4 .6 and 5 .6 was s i g n i f i c a n t l y h i g h e r th a n t h a t a t
pH 6 . 6 .
A ll th e s u g a r s t e s t e d s u p p o r te d g e r m in a tio n e q u a l ly w e l l .
The e f f e c t o f v a r i o u s g lu c o s e c o n c e n t r a t i o n s on g e r m in a tio n o f
c o n i d ia i s shown in T a b le IX .
I n c o n c e n t r a t i o n s g r e a t e r th a n 10~^M,
g lu c o s e s ti m u l a t e d g e r m in a tio n .
To d e te r m in e i f m y c e lia l g ro w th o f C. p u r p u r e a i s a f f e c t e d by
pH, ACD m ed ia w ith i t s pH a d j u s t e d b y th e a d d i t i o n o f 0.1M KOH was
37
TABLE V I I I .
E f f e c t o f ca rb o n s o u r c e and pH on g e r m in a tio n o f
c o n i d i a o f C la v ic e p s p u r p u r e a .
a/
7. G e rm in a tio n —
PH
T re a tm e n t
W ater
4 .6
5 .6
6 .6
2
O
O
0.1M G lu co se
87
83
11
0.1M F r u c to s e
77
64
O
0.1M S u c ro s e
80
73
I
0.1M M e lib io s e
74
77
O
0.1M G lu c o s e r F r u c to s e :
S u c r o s e r M e lib io s e
(Irlrlrl)
94
81
15
a/
In c u b a te d 24 h r s a t 3 0 °C; a 0.05M c i t r a t e p h o s p h a te b u f f e r was
u s e d t o c o n t r o l pH.
38
TABLE IX .
E f f e c t o f g l u c o s e c o n c e n t r a t io n on g e r m in a tio n o f
c o n i d ia o f C la v ic e p s p u r p u r e a .
G lu co se c o n c e n t r a t i o n (M o la r)
a/
a/
% G e rm in a tio n —
0 .1
65
0 .0 1
49
0 .0 0 1
46
0 .0 0 0 1
20
0 .0 0 0 0 1
14
H2 O
14
In c u b a te d 30 h o u r s a t 2 5°C .
39
used.
The r e s u l t s shown i n T a b le X i n d i c a t e t h a t g ro w th i s b e s t a t
pH 4 . 8 .
F u n g ic id e s t u d i e s . -
P o is o n fo o d t e s t s i n d i c a t e d t h a t th e
fo llo w in g m a t e r i a l s d id n o t ? i n h i b i t g ro w th o f C. p u r p u r e a .
A ll
m in e r a l o i l s a t 8000 ppm, a l l p erfu m e o i l s a t 2000 ppm, PCNB a t 5000
ppm, and th i a b e n d a z o le a t 1 2 ,5 0 0 ppm.
The e f f e c t o f b en o m y l, D ith a n e
M 4 5 , and nabam on l i n e a r g ro w th a r e shown i n T a b le X I.
The d a t a
i n d i c a t e t h a t benom yl i n h i b i t e d g ro w th m ore th a n 507. a t l e v e l s o f
2 ppm and a b o v e .
e x t e n t a t 10 ppm.
D ith a n e M45 and nabam d id n o t i n h i b i t g ro w th to any
When m y c e lia l d i s c s i n c o n t a c t w ith 400 ppm benom yl
f o r 17 d ay s w ere rem oved and r e p l a n t e d on f r e s h ACD a g a r w ith o u t
b en o m y l, g ro w th o f C la v ic e p s resu m ed i n d i c a t i n g t h a t benom yl i s
f u n g is ta tic in i t s a c tio n .
I n s t u d i e s on th e e f f e c t o f v a r io u s
c o n c e n t r a t i o n s o f benom yl o n m y c e l i a l d ry w e ig h t, 100 ppm benom yl
re d u c e d th e d ry w e ig h t b y 98 p e r c e n t ( T a b le X I I ) .
D ith a n e M 45 was
m o d e ra te ly i n h i b i t o r y a t c o n c e n t r a t i o n s down to 9 ppm.
I n f i e l d e x p e r im e n ts i n 1 9 6 8 , m ale s t e r i l e b a r l e y p l a n t s l e f t
f o r n a t u r a l i n f e c t i o n w ere s p ra y e d o n e tim e d u r in g a n t h e s i s w ith
s e v e r a l f u n g i c i d e s , p erfu m e o i l s o r m in e r a l o i l s .
T hose f u n g ic i d e s
r e p o r t e d to b e s y s te m ic i n p l a n t s w ere s p ra y e d p r i o r t o o r d u r in g
a n th e s is .
Benomyl s p ra y e d a t th e r a t e o f 500 ppm re d u c e d t h e p e r
c e n t o f h e a d s w ith a t l e a s t o n e s c le r o t iu m fro m 947. to 777. ( T a b le
40
TABLE X.
I n i t i a l pH
Effect of pH on growth of Claviceps purpurea on
ACD media.
M y c e lia l Dry W t.
ing
4 .8
4 4 3 .3
5 .4
4 1 .2
6 .0
2 7 .8
6 .6
2 0 .0
Grown f o r 20 d a y s a t room te m p e r a tu r e w ith a t l e a s t 2
r e p l i c a t i o n s f o r e a c h t r e a t m e n t . pH a d j u s t e d b y th e
a d d i t i o n o f KOH.
41
TABLE X I.
F u n g ic id e
E f f e c t o f b e n o m y l, nabam , and D ith a n e M 45 o n
m y c e lia l g ro w th o f C le v ic e p s o n ACD a g a r .
C o n c e n tr a tio n
( a c tiv e in g re d ie n t)
7. I n h i b i t i o n
ppm
Benomyl
0 .1
0
I
13
2
60
4
68
6
85
8
92
10
98
20
100
100
100
Nabam
10
13
D ith a n e M 45
10
6
a/
R e p l ic a t e d a t l e a s t 3 tim e s
—
42
TABLE X I I .
F u n g ic id e
E f f e c t o f v a r i o u s c o n c e n t r a t i o n o f D ith a n e M 45
and benom yl on m y c e lia l d r y w e ig h t o f C la v ic e p s
p u r p u r e a o n ACD m e d ia .
C o n c e n tr a tio n
( a c tiv e in g re d ie n t)
. 7. i n h i b i t i o n
ppm
D ith a n e M 45
Benomyl
a/
R e p l ic a t e d a t l e a s t 2 ti m e s .
0 .9
34
9
75
90
72
0 .5
11
5 .6
25
10
74
56
93
100
98
330
95
~
43
X III) .
An a p p l i c a t i o n o f C a p ta n a t t h e r a t e o f 1600 ppm d u r in g
a n t h e s i s a l s o re d u c e d i n f e c t i o n by 24%, w h ile some o f t h e o t h e r
m a t e r i a l s re d u c e d i n f e c t i o n o n ly a v e r y s m a ll e x t e n t .
To d e te r m in e i f s o i l a p p l i c a t i o n o f benom yl w ould a llo w enough
m a t e r i a l to b e t r a n s l o c a t e d t o th e h e a d s and th u s c o n t r o l i n f e c t i o n ,
a f i e l d t r i a l was s e t up i n 1969 u s i n g 3 0 , 9 0 , 150 and 210 l b s p e r
a c re o f a c tiv e in g r e d ie n t.
The f u n g ic i d e was a p p l ie d to t h e fu rro w s
a t th e tim e o f s e e d in g i n 30 cm ro w s.
I n a d d i t i o n , some o f th e p l a n t s
a l s o r e c e iv e d a f o l i a r and h e a d a p p l i c a t i o n o f f u n g ic i d e s a t v a r io u s
tim e s .
The p l a n t s w ere i n o c u l a t e d d u r in g a n t h e s i s w ith a c o n i d i a l
s u s p e n s io n (10^ c o n i d ia /m l) u s in g a b a c k p a c k s p r a y e r .
No c o n t r o l
was o b ta in e d b y t h e s o l e u s e o f any o f t h e s o i l a p p l i c a t i o n s ( T a b le
X IV )
.
Some c o n t r o l d id r e s u l t when 500 an d 1000 ppm benom yl w ere
a p p lie d p r i o r to o r d u r in g a n t h e s i s .
D ith a n e M 45 and C ap ta n f o l i a r
a p p l i c a t i o n s d u r in g a n t h e s i s f a i l e d t o p r o v id e an y c o n t r o l .
S in c e f o l i a r a p p l i c a t i o n o f benom yl p ro v id e d a s l i g h t am ount o f
c o n t r o l i n t h e 1968 and 1969 f i e l d t r i a l s , f u r t h e r f i e l d t e s t s w ere
c o n d u c te d i n 19 7 0 .
M ale s t e r i l e b a r l e y p l a n t s w ere i n o c u l a t e d t h r e e
tim e s a t 4 - 7 d ay s i n t e r v a l s d u r in g a n t h e s i s w ith a c o n i d i a l s u s p e n s io n
(10^ c o n i d ia /m l) u s in g a b a c k p a c k s p r a y e r . T e c h n ic a l benom yl was a p p l i ­
ed a t th e r a t e o f I and 2 I b s / a c r e i n 100 g a l l o n s o f w a te r ( a b o u t 1200
and 2400 ppm, r e s p e c t i v e l y ) .
S in c e i n s e c t s a r e b e l i e v e d to b e th e
44
TABLE X I I I .
C o n tr o l o f e r g o t i n m ale s t e r i l e b a r l e y u n d e r f i e l d
c o n d i t i o n s w ith v a r i o u s c h e m ic a ls .
C hem ical
C o n c e n tr a tio n
% H eads i n f e c t e d
ppm
None
M in e ra l o i l s
LS 1195
LS 1183
LS 1197
LS 925
O rch ex 796
O rch ex 792
P erfum e o i l s
Palm a B ouquet
B lu e S to n e B o u q u et
B ou q u et 22
C ap tan
C opper s u l f a t e
B ay er 33172
U n iro y a l G696
U n iro y a l F849
94
4 0 ,0 0 0
4 0 ,0 0 0
4 0 ,0 0 0
4 0 ,0 0 0
4 0 ,0 0 0
4 0 ,0 0 0
96
85
82
86
92
93
2 ,0 0 0
2 ,0 0 0
2 ,0 0 0
1 ,2 0 0
1 ,6 0 0
2 ,0 0 0
100
500
100
500
725
2 ,0 0 0
91
97
82
90
70
88
90
88
94
97
91
88
.
TBZ
s p ra y e d p r i o r t o a n t h e s i s
s p ra y e d d u r in g a n t h e s i s
Benomyl
s p ra y e d p r i o r to a n t h e s i s
s p ra y e d d u r in g a n t h e s i s
100
500
100
500
100
500
100
94
90
83
^
ioo U
500
—
S u r f a c t a n t T r i t o n X-77 ad d ed ( 0 .2 m l / l i t e r ) .
—^
S u r f a c t a n t F was ad d ed to benom yl ( 0 .5 m l / l i t e r )
97
98
94
77
45
TABLE XIV.
Application of fungicides to the soil and/or foliage
and heads of field grown male sterile barley for
control of ergot.
Foliar and Head
C hem ical
None
Benomyl
S o il
concen­
tra tio n
Ib /a c re
ppm
30
90
150
210
30
30
30
30
30
90
90
90
90
90
——
——
——
«• —
■■
——
——
——
——
• —
ww
D ith a n e M 45
W
W
WWW
W
C ap tan
——
W
W
W
W
——
a/
-T ,
—
g ro w th
s ta g e
# of
a p p l.
WW
WW
W
W
WW
WW
W
W
W
W
WW
W
W
W
W
500
500
500
5 0Q
500
500
500
500
500
500
500
500
500
500
500
1000
1000
1000
1000
1000
1000
500
1000
1000
500
1000
1000
1000
W
W
i r
l *
W
W
WW
WW
WW
WW
WW
WW
WW
WW
WW
WW
ww
P re
Dur
WW
WW
W
W
WW
WW
WW
WW
. WW
WW
WW
——
P r e - A p p lic a tio n a p p l ie d p r i o r to a n t h e s i s .
Dur - A p p lic a tio n a p p l i e d d u r in g a n t h e s i s .
I
2
3
4
5
I
2
3
4
5
I
I
2
3
4
I
I
2
3
4
5
I
2
3
I
I
2
4
% H eads
in fe c te d
85
83
78
78
79
87
80
79
79
81
75
66
70
70
79
78
72
73
75
78
71
76
66
70
71
66
80
82
59
83
83
84
83
46
m ain v e c t o r s o f in o c u lu m , a b r o a d s p e c tru m i n s e c t i c i d e , d i a z i n o n , was
a l s o a p p l ie d to s e e i f i n s e c t c o n t r o l w ould a l s o r e s u l t i n e r g o t
c o n tro l.
On th e b a s i s o f h e a d s i n f e c t e d , d ia z in o n a t 2 p i n t s / a c r e
and benom yl a t I and 2 I b s / a c r e p r o v id e d some c o n t r o l ( T a b le XV).
When th e p e r c e n t o f f l o r e t s i n f e c t e d was c o n s id e r e d a l l th e t r e a t ­
m en ts p r o v id e d c o n t r o l , p a r t i c u l a r l y benom yl a t 2 I b s / a c r e .
S in c e u n d e r n a t u r a l c o n d i t i o n s th e maximum r e d u c t i o n i n p e r c e n t ­
age o f h e a d s i n f e c t e d b y a p p l i c a t i o n o f benom yl was o n ly 297. (T a b le
XV), th e p o s s i b i l i t y e x i s t e d t h a t t h e f u n g ic i d e was n o t alw ay s
r e a c h in g th e o v a ry s u r f a c e .
T h e r e f o r e , a t e s t was s e t up i n w h ich
th e glum es o f m ale s t e r i l e b a r l e y f l o r e t s w ere c l ip p e d b a c k p r i o r to
a p p l i c a t i o n o f th e f u n g i c i d e , th u s a llo w in g e n t r y o f t h e f u n g ic i d e
i n t o th e f l o r e t .
U nder t h e s e c o n d i t i o n s benom yl p r o v id e d e x c e l l e n t
c o n t r o l r e d u c in g th e f l o r e t i n f e c t i o n from 837. to 57. ( T a b le X V I).
Nabam a l s o re d u c e d i n f e c t i o n b u t n o t to t h e e x t e n t a s b en o m y l.
D ith a n e M 45 p r o v id e d l i t t l e
c o n tro l.
G reen h o u se s t u d i e s o f f u n g i c i d e s f o r e r g o t c o n t r o l w ere a l s o
u n d e r ta k e n t o c o l l a b o r a t e t h e in f o r m a tio n c o l l e c t e d i n th e f i e l d .
Male s t e r i l e b a r l e y f l o r e t s w ere c l ip p e d and i n o c u l a t e d w ith an
a to m iz e r .
Benomyl and e t h i r i m o l w ere th e n im m e d ia te ly a to m iz e d o n to
th e in o c u l a t e d f l o r e t s .
Benomyl p r o v id e d some c o n t r o l o f e r g o t a t
500 ppm b u t d id n o t c o m p le te ly c o n t r o l i n f e c t i o n ev en a t 2000 ppm
47
TABLE XV.
Foliar and head application of benomyl or diazinon
for control of ergot in field grown male sterile
barley.
T re a tm e n t
None
% H eads
in fe c te d
7. F l o r e t s
in fe c te d
100
74
a/
D ia z in o n —
I p in t/a c re
99
60
D ia z in o n —^
2 p in ts /a c re
82
59
I lb /a c re
82
46
2 lb /a c re
71
26
C/
Benomyl —
C/
Benomyl —
—
Applied once prior to anthesis.
—^
Applied three times during anthesis.
C/
—
A p p lie d t h r e e tim e s p r i o r t o and d u r in g a n t h e s i s a t 4 -7
day i n t e r v a l s .
48
TABLE XVI.
F u n g ic id e
F u n g ic i d a l c o n t r o l o f e r g o t i n f i e l d grown m ale
s t e r i l e b a r l e y w ith c l ip p e d g lu m e s .
—
1»
F lo r e ts in fe c te d
None
83
D ith a n e M 45
76
Nabam
30
Benomyl
a/
—
5
A p p lie d a t 1000 ppm o f a c t i v e i n g r e d i e n t im m e d ia te ly a f t e r
in o c u la tio n .
49
(T a b le X V II).
C om plete c o n t r o l o f e r g o t how ever was a c c o m p lish e d
when a w e tt in g a g e n t su c h a s T r i t o n X-77 (Rohm and H aas C o .,
P h i l a d e l p h i a , P a . ) and M u l t i f i l m B u f f e r X ( C o l l o i d a l P r o d u c ts
C o r p o r a tio n , S a n s a l i t e , C a l i f . ) w ere u s e d i n c o n j u n c tio n w ith benom yl
a t 1000 ppm.
E t h i r i m o l , a s y s te m ic f u n g ic i d e w h ich i s e f f e c t i v e
a g a i n s t pow dery m ild ew s (W atso n , G .A ., p e r s o n a l c o m m u n ica tio n ) a t
1000 ppm was o n ly s l i g h t l y e f f e c t i v e i n c o n t r o l l i n g e r g o t .
To d e te r m in e i f benom yl c a n a c t a s a n e r a d i c a n t a s r e p o r t e d by
D elp and K lo p p in g ( 1 5 ) f o r s e v e r a l f u n g i , t h e f l o r e t s o f g re e n h o u s e
grown m ale s t e r i l e b a r l e y w ere i n o c u l a t e d a s d e s c r ib e d a b o v e .
Benomyl was th e n a to m iz e d o n to t h e f l o r e t s e i t h e r o n th e same d ay a s
i n o c u l a t i o n o r 2 and 4 d a y s a f t e r i n o c u l a t i o n .
The r e s u l t s shown i n
T a b le X V III i n d i c a t e t h a t benom yl a t 2000 ppm d id n o t a c t a s an
e ra d ic a n t.
To d e te r m in e i f r e s i d u e s o f benom yl o r i t s b reak d o w n p r o d u c t
rem a in ed on f l o r e t s o f f i e l d grow n m a le s t e r i l e b a r l e y , n o n - i n f e c t e d
f l o r e t s w ere rem oved from p l a n t s t h a t h ad b e e n p r e v i o u s l y s p ra y e d
t h r e e tim e s w ith benom yl a t t h e r a t e o f I o r 2 I b s / a c r e .
The l a s t
s p ra y was a p p l ie d 22 d a y s p r i o r t o t h e a n a l y s i s o f th e f l o r e t s .
The
o v a r i e s w ere rem oved i n t a c t and p la c e d o n s o l i d i f i e d p o t a t o - d e x t r o s e a g a r i n w h ich c o n i d i a o f P . expansum (1 0 ^ c o n i d ia /m l) h ad b e e n in c o r p ­
o ra te d .
T h is p a r t i c u l a r i s o l a t e o f £ . expansum was known to b e s e n s i t ­
iv e to benom yl a t c o n c e n t r a t i o n s down to 0 .4 ppm. Tw enty p e r c e n t and 757.
50
TABLE XVII.
F u n g ic id e
Control of ergot in greenhouse grown male sterile
barley with benomyl. Effect of fungicide concen­
tration and use of wetting agents.
C o n c e n tr a tio n
W e ttin g a g e n t
7. F l o r e t s ,
in fe c te d —
ppm
None
94
Benomyl
E t h ir im o l
a/
—
—^
500
14
750
11
1000
11
1500
9
2000
6
1000
X-77
1000
M u ltifilm
0
1000
Tween 80 —^
6
1000
- f
0
69
Glumes w ere c l ip p e d b a c k , i n o c u l a t e d w ith a c o n ! d i a l s u s p e n s io n
(IO 6 c o n i d ia /m l) u s i n g an a t o m iz e r . F u n g ic id e s w ere a p p l i e d
im m e d ia te ly a f t e r i n o c u l a t i o n w ith an a t o m iz e r .
I ml f o r 200 ml o f f u n g i c i d e .
51
TABLE X V III.
F u n g ic id e —^
E f f e c t i v e n e s s o f benom yl a s s n e r a d i c a n t o f e r g o t
i n f e c t i o n i n g re e n h o u s e grow n m a le s t e r i l e b a r l e y .
A p p l i c a t i o n tim e
7. F l o r e t s i n f e c t e d
—
98
None
Benomyl
0 days a f t e r In o c .
11
Benomyl
2 d a y s a f t e r in o c .
63
Benomyl
4 d a y s a f t e r in o c .
97
—
A c o n i d i a l s u s p e n s io n (1 0
w ith glum es c l ip p e d b a c k .
tu b e .
W
2000 ppm
c o n i d ia /m l) was a to m iz e d o n to f l o r e t s
Benomyl was a p p l i e d w ith a c a p i l l a r y
52
o f o v a r i e s o f f l o r e t s s p ra y e d w ith I and 2 l b s p e r a c r e , r e s p e c t i v e l y ,
showed i n h i b i t i o n z o n e s , i n d i c a t i n g a r e s i d u a l e f f e c t f o r a t l e a s t
22 d a y s .
T h ese d a t a a l s o i n d i c a t e t h a t benom yl d id n o t r e a c h a l l o f
th e f l o r e t s .
T h is may b e t h e r e a s o n why o n ly p a r t i a l c o n t r o l o f e r g o t
i s a c h ie v e d w ith u s e o f t h i s m a t e r i a l .
DISCUSSION
The s e r io u s n e s s o f e r g o t c a u s e d b y C. p u r p u r e a i n m a le s t e r i l e
c e r e a l s i s i l l u s t r a t e d by t h e o b s e r v a t i o n t h a t i n 19 70 767. o f th e
h e a d s and 367. o f th e f l o r e t s o f m ale s t e r i l e b a r l e y w ere i n f e c t e d
u n d e r n a t u r a l c o n d i t i o n s i n f i e l d p l o t s a t Bozem an, M o n tan a.
S im i la r
l e v e l s o f i n f e c t i o n h a v e a l s o b e e n o b s e rv e d i n o t h e r a r e a s o f M ontana
p a r t i c u l a r l y i n f i e l d s u n d e r fu rro w i r r i g a t i o n ( M ath re , p e r s o n a l
c o m m u n ic a tio n ).
T h ese l e v e l s o f i n f e s t a t i o n w ould c a u s e n o t o n ly
l o s s i n y i e l d b u t g r a i n p ro d u c e d f o r h y b r id s e e d w ould h a v e to b e
c le a n e d to rem ove th e num erous e r g o t s c l e r o t i a .
T hus, c o n tro l o f
e r g o t by u s e o f c h e m ic a ls , v a r i o u s c u l t u r a l p r a c t i c e s , o r p l a n t
r e s i s t a n c e i s e s s e n t i a l b e f o r e p r o d u c ti o n o f w h e a t and b a r l e y h y b r id
s e e d i n M ontana w i l l b e s u c c e s s f u l .
The te c h n iq u e r e p o r t e d h e r e o f c l i p p i n g b a c k glum es and in o c u l ­
a t i n g o n e tim e w ith an a q u e o u s c o n i d i a l s u s p e n s io n o f IO^ c o n id ia /m l
r e s u l t e d in i n f e c t i o n o f 1007. o f t h e h e a d s o f m a le s t e r i l e w h eat
and b a r l e y .
T h is i s i n c o n t r a s t t o i n f e c t i o n l e v e l s o f 20-607. r e p o r t
ed i n e a r l i e r s t u d i e s o f f e r t i l e g r a i n ( 2 6 ) .
I f o n ly th e awns a r e
c l i p p e d , th e p e r c e n ta g e o f f l o r e t s i n f e c t e d v a r i e s a g r e a t d e a l ,
p r o b a b ly due to th e v a r i a t i o n i n t h e num ber o f f l o r e t s o p en a t th e
tim e o f i n o c u l a t i o n .
The o b s e r v a t i o n t h a t th e i n f e c t i o n p e r c e n ta g e
f o r f l o r e t s o f m ale s t e r i l e w h e a t i s lo w e r (807.) th a n t h a t f o r m ale
s t e r i l e b a r l e y (95-98% ) i s p r o b a b ly r e l a t e d t o t h e f a c t t h a t w h eat
54
f l o r e t s h o ld a s m a l le r volum e o f in o cu lu m th a n do b a r l e y f l o r e t s .
The c l o s e f i t o f th e w h eat g lu m e s, p a l e a , and lemma a r e r e s p o n s i b l e
f o r th e d e c r e a s e d volum e h e l d by th e f l o r e t s .
I n o c u l a t i o n o f f l o r e t s w ith a n a to m iz e r r e s u l t e d i n s l i g h t l y
h ig h e r l e v e l s o f i n f e c t i o n th a n w ere o b s e rv e d when th e in o cu lu m was
d ro p p ed i n t o th e f l o r e t w ith a c a p i l l a r y t u b e .
The f o r c i b l e d is c h a r g e
o f th e c o n i d ia i n t o t h e f l o r e t when an a to m iz e r i s u s e d may r e s u l t i n
more c o n i d ia r e a c h in g th e b a s e o f th e o v a ry w h ich i s r e p o r t e d to b e
th e s i t e o f i n f e c t i o n ( 6 ) .
I n a d d i t i o n , m ore in o c u lu m te n d s to ru n
o f f th e s id e o f th e f l o r e t s when a p p l i e d w ith a c a p i l l a r y .
H ow ever,
th e m ethod o f i n o c u l a t i o n by u s e o f a c a p i l l a r y may b e d e s i r a b l e i f
c o n t r o l l e d l e v e l s o f in o c u lu m a r e n e e d e d i n s t u d i e s o f th e r e l a t i v e
s u s c e p t i b i l i t y o f d i f f e r e n t g e n e t i c l i n e s o f w h eat o r b a r l e y .
The
d is a d v a n ta g e o f th e c a p i l l a r y i n o c u l a t i o n te c h n iq u e i s i t s tim e
c o n su m p tio n .
S tu d ie s o f th e e f f e c t o f in o cu lu m d e n s i t y on i n f e c t i o n i n d i c a t e d
t h a t v e r y few c o n i d i a a r e n e e d e d t o i n f e c t o n e o v a r y , p r o b a b ly no
m ore th a n 1 -1 0 ( F i g . 2 ) .
H ow ever, maximum p e r c e n ta g e i n f e c t i o n i s
o b ta in e d when 2000 o r m ore c o n i d i a p e r o v a ry a r e u s e d .
T h is num ber
o f c o n i d ia i s p r o b a b ly n o t to o d i f f e r e n t from t h a t t h a t w ould b e
found on th e body and l e g s o f an i n s e c t t h a t h ad p r e v i o u s l y v i s i t e d
a honey dew f l o r e t ( 2 ) .
55
The c o n i d ia o f C. p u r p u r e a g e r m in a te v e r y p o o r ly i n w a te r .
G lu c o s e , f r u c t o s e , m e lib l o s e , and s u c r o s e w ere a b l e to s t i m u l a t e
g e rm in a tio n to l e v e l s o f 74-877..
A m ix tu r e o f t h e s e s u g a r s was ev en
m ore e f f e c t i v e i n s t i m u l a t i n g g e r m in a tio n , r e s u l t i n g i n 947. g e rm in ­
a tio n .
U nder n a t u r a l c o n d i t i o n s e i t h e r t h e c o n s t i t u e n t s o f ho n ey dew
o r compounds on th e s u r f a c e o f th e o v a ry c o u ld b e a s o u rc e o f m a t e r i ­
a l s n e c e s s a r y f o r c o n i d i a l g e r m in a tio n .
G lu c o se and f r u c t o s e w ere
found i n b o th honey dew and w a s h in g s o f o v a r i e s and th u s c o u ld p la y
a r o l e i n c o n i d i a l g e r m in a tio n .
W h eth er t h e s e s u g a r s a r e p r e s e n t in
c o n c e n t r a t i o n s h ig h enough to b e e f f e c t i v e i n s t i m u l a t i n g g e r m in a tio n
was n o t d e te r m in e d , b u t K ir c h h o f f ( 3 0 ) r e p o r t e d t h a t honey dew i s
2 .3 3 m o la r i n s u c r o s e e q u i v a l e n t s .
S in c e c o n i d i a w ould g e r m in a te
w e ll in 0 .1 M s o l u t i o n s o f v a r i o u s s u g a r s (T a b le V I I I ) i t seem s t h a t
th e s u g a r s i n honey dew a r e l i k e l y t o b e p r e s e n t i n s u f f i c i e n t q u a n t­
i t y to i n s u r e r a p i d g e r m in a tio n o f c o n i d ia o n th e o v a ry s u r f a c e .
The e f f e c t o f pH on c o n i d i a l g e r m in a tio n and m y c e lia l g ro w th ,
i . e . , p o o r g e r m in a tio n and g ro w th a t pH 6 .6 was som ew hat s u r p r i s i n g .
H ow ever, i n v ie w o f t h e f a c t t h a t th e pH o f o v a r y t i s s u e and w a sh in g s
was a b o u t 5 . 4 , th e n e c e s s i t y f o r f a i r l y a c id c o n d i t i o n s f o r g erm in ­
a t i o n and g ro w th d o e s n o t a p p e a r t o b e d is a d v a n ta g e o u s t o C. p u r p u r e a .
U nder m o st c o n d i t i o n s f e r t i l e b a r l e y and p a r t i c u l a r l y f e r t i l e
w h eat a r e r a r e l y a t t a c k e d by C. p u r p u r e a .
T h is r e s i s t a n c e i s
56
b e l ie v e d to b e f u n c t i o n a l i n n a t u r e d u e t o th e f a c t t h a t th e c e r e a l s
a r e l a r g e l y s e l f p o l l i n a t e d and h i g h l y f e r t i l e .
H e n c e , th e f lo w e r s
a r e n o t o p en to r e c e i v e in o c u lu m o f G. p u r p u r e a .
I n a d d i t i o n , no
s p e c i f i c r e p o r t s h a v e a p p e a re d t o i n d i c a t e t h a t t h e r e a r e g e n e s f o r
r e s i s t a n c e to e r g o t i n w h e a t o r b a r l e y .
I n M o n tan a, h o w ev er, th e
g e n e r a l e x p e r ie n c e o f g ro w e rs i s t h a t Hypana f e r t i l e b a r l e y i s much
more s u s c e p t i b l e t o e r g o t th a n t h e v a r i e t y Compana.
As a p a r t o f o u r
s t u d i e s o f r e s i s t a n c e t o C. p u r p u r e a , th e r e a c t i o n to e r g o t o f th e s e
two f e r t i l e b a r l e y v a r i e t i e s was t e s t e d i n a d d i t i o n t o v a r i o u s l i n e s
o f m ale s t e r i l e w h e a t.
U nder g re e n h o u s e c o n d i t i o n s , b o th Hypana and
Compana w ere e q u a l ly s u s c e p t i b l e to a r t i f i c i a l i n o c u l a t i o n w ith C.
p u r p u r e a (T a b le I I ) .
H ow ever, H ypana was fo u n d to h a v e a s l i g h t l y
h ig h e r d e g re e o f s t e r i l i t y th a n Compana and t h i s may c o n t r i b u t e to th e
h ig h e r d e g re e o f e r g o t i n f e s t a t i o n i n t h i s v a r i e t y .
o f f e r t i l i z e d o v a r i e s can o c c u r ( T a b le I I ) ,
H ow ever, i n f e c t i o n
so e n v iro n m e n ta l c o n d i tio n s
t h a t e f f e c t th e l e n g t h o f tim e t h e f lo w e r s a r e o p e n may a l s o b e
im p o r ta n t i n d e te r m in in g th e s u s c e p t i b i l i t y o f th e s e two v a r i e t i e s
under f i e l d c o n d itio n s .
The d u r a t i o n o f th e p e r i o d o f s u s c e p t i b i l i t y o f f e r t i l i z e d and
u n f e r t i l i z e d b a r l e y o v a r i e s , r e s p e c t i v e l y , was 9 and 15 d a y s a f t e r
a n t h e s i s , th u s c o n f ir m in g t h e e a r l i e r w ork o f K ir c h h o f f w ith f e r t i l e
ry e .
F e r t i l i z e d o v a r i e s o f m ale s t e r i l e b a r l e y w ere h ig h l y s u s c e p t i b l e
57
d u r in g th e f i r s t f i v e d a y s f o llo w in g f e r t i l i z a t i o n , w ith r e s i s t a n c e
a p p e a rin g to d e v e lo p a f t e r th e f i f t h d a y , u n t i l no i n f e c t i o n o c c u r r e d
p a s t th e t e n t h day ( F i g . 4 ) .
T h is s u g g e s ts t h a t i f p r o t e c t i v e chem­
i c a l s c o u ld b e p la c e d on th e o v a r y d u r in g t h e 1 0-15 d ay p e r i o d f o llo w ­
in g a n t h e s i s , th e p l a n t w ould b e p r o t e c t e d fro m i n f e c t i o n u n t i l th e
r e s i s t a n c e m echanism s i n th e f e r t i l i z e d o v a ry becam e e f f e c t i v e .
H ow ever,
u n d e r f i e l d c o n d i t i o n s p l a n t s p ro d u c e t i l l e r s o v e r a
c o n s id e r a b le le n g t h o f tim e th u s r e s u l t i n g i n h e a d s i n v a r i o u s s ta g e s
o f d e v e lo p m e n t.
T h is w ould n e c e s s i t a t e th e m u l t i p l e a p p l i c a t i o n o f
p r o t e c t i v e c h e m ic a ls to make s u r e t h a t a l l o v a r i e s r e c e i v e d p r o t e c t i o n
a s th e y d e v e lo p .
Among th e m ale s t e r i l e w h e a t v a r i e t i e s t e s t e d , t h e r e a p p e a r s to
b e v a r y in g d e g r e e s o f s u s c e p t i b i l i t y .
The v a r i e t y C h r is n o t o n ly
had fe w e r h e a d s i n f e c t e d th a n th e o t h e r v a r i e t i e s , b u t w i t h i n an
i n f e c t e d h e a d fe w e r f l o r e t s w ere a l s o i n f e c t e d .
H ow ever, w i t h i n any
o f th e v a r i e t i e s t e s t e d d i f f e r e n t f l o r e t c h a r a c t e r i s t i c s w ere fo u n d ,
su ch a s awned f l o r e t s and a w n le s s f l o r e t s .
T h is may b e due to m ix­
t u r e s i n th e s e e d l o t s o r to s e g r e g a t i o n w ith t h e v a r i e t y .
T h u s, th e
o b s e r v a ti o n s r e p o r t e d h e r e on t h e s e d i f f e r e n t w h e a t v a r i e t i e s may b e
somewhat i n e r r o r due t o g e n e t i c v a r i a t i o n re m a in in g w i t h i n a g iv e n
v a rie ty .
58
W h ile C h erew ick ( 8 ) and L ew is (3 7 ) h av e d e m o n s tr a te d t h a t th e
e r g o t fu n g u s may d e v e lo p on p h y s i o l o g i c a l l y young t i s s u e o f w h e a t,
r y e , and b a r l e y , i t i s n o t known w h e th e r t h e r e i s any c o r r e l a t i o n
b e tw e e n s e e d li n g i n f e c t i o n and o v a r y i n f e c t i o n .
U n t i l t h i s i s known,
s t u d i e s on r e s i s t a n c e t o e r g o t w i l l n e e d to b e c a r r i e d o u t u n d e r
c o n d i t i o n s w here known am ounts o f in o cu lu m a r e a p p l i e d to th e f lo w e r ­
in g p l a n t s a s d e s c r ib e d h e r e i n .
The p o s s i b i l i t y o f u s i n g a s y s te m ic f u n g ic i d e f o r c o n t r o l o f
e r g o t was f i r s t e x p lo r e d b y H a r d is o n (2 5 ) who r e p o r t e d t h a t a w a te r
s u s p e n s io n o f benom yl a p p l ie d to s o i l aro u n d g r e e n o u s e grown M erion
b l u e g r a s s p l a n t s w ould c o n t r o l e r g o t .
H ow ever, th e q u a n t i t y o f
benom yl a p p l ie d and th e e x t e n t o f d i s e a s e c o n t r o l w ere n o t r e p o r t e d .
P r e li m in a r y t e s t s b y me i n d i c a t e d t h a t w ith m ale s t e r i l e b a r l e y ,
s e e d g e r m in a tio n was a d v e r s e l y a f f e c t e d b y s o i l a p p l i c a t i o n s o f
benom yl a t r a t e s o f 60 l b / a c r e and h i g h e r .
M o re o v e r, when benom yl
was a p p l ie d to th e f u rro w a t r a t e s up to 210 I b s / a c r e no c o n t r o l o f
e r g o t was o b s e r v e d .
T h u s, s o i l a p p l i c a t i o n s o f benom yl f o r c o n t r o l
o f e r g o t i n b a r l e y do n o t a p p e a r f e a s i b l e .
H ow ever, c o n t r o l o f e r g o t
i n m ale s t e r i l e b a r l e y was o b ta in e d when th e h e a d s w ere s p ra y e d
w ith benom yl a t th e r a t e o f 2 I b s / a c r e i n 100 g a l l o n s o f w a te r
(T a b le XV).
I n t h i s c a s e t h e f u n g ic i d e was a p p l ie d 3 tim e s o v e r a
p e r i o d o f 18 d a y s and d e c r e a s e d th e p e r c e n t o f h e a d s i n f e c t e d by 34%.
59
Lower d o s a g e s o f benom yl p r o v id e d o n ly a s l i g h t d e g r e e o f c o n t r o l .
A n o th e r p ro b le m i n th e u s e o f benom yl f o r e r g o t c o n t r o l a p p e a rs
to in v o lv e th e p e n e t r a t i o n o f th e c h e m ic a l t o t h e o v a ry s u r f a c e .
When u n c lip p e d glum es w ere s p r a y e d , t h e r e was a b o u t a 307. r e d u c t i o n
in i n f e c t i o n b u t i f th e glum es w ere c l ip p e d p r i o r to s p r a y in g o f
ben o m y l, a 957. r e d u c t i o n i n i n f e c t i o n r e s u l t e d .
T h is i n d i c a t e s t h a t
benom yl r e a c h e d th e o v a r y s u r f a c e i n much g r e a t e r am ounts when p l a n t
t i s s u e i . e . , th e u p p e r p a r t s o f th e g lu m es, w ere rem oved.
T h u s,
benom yl h a s th e p o t e n t i a l f o r c o n t r o l l i n g e r g o t i n f e c t i o n s i f i t can
r e a c h th e o v a r y s u r f a c e .
S in c e th e f u n g ic i d e m u st r e a c h th e o v a ry
s u r f a c e to b e e f f e c t i v e , th e p e r c e n ta g e o f f l o r e t s i n a n t h e s i s a t
th e tim e o f f u n g ic i d e a p p l i c a t i o n w ould a f f e c t th e d e g r e e o f e r g o t
c o n tro l.
I n a d d i t i o n , th e f a c t t h a t benom yl d o e s n o t a p p e a r to h av e
an e r a d i c a n t e f f e c t o n o v a r y i n f e c t i o n (T a b le X V I I I ) , w ould n e c e s s i t ­
a t e th e a p p l i c a t i o n o f benom yl p r i o r to i n f e c t i o n , p r o b a b ly soon
a f t e r th e f l o r e t s o p en .
T h u s, th e lo n g e r t h e d u r a t i o n o f t i l l e r i n g
o f th e p l a n t s , th e lo n g e r w ould b e th e o v e r a l l p e r i o d f o r o p en f l o r e t s .
Such a c o n d i tio n w ould n e c e s s i t a t e m u l t i p l e a p p l i c a t i o n s o f f u n g ic i d e
u n l e s s th e am ount o f t i l l e r i n g i s c o n t r o l l e d .
The u s e o f w e tt in g a g e n t s , su c h a s T r i t o n X-77 a p p e a re d to
i n c r e a s e th e e f f e c t i v e n e s s o f benom yl p r o b a b ly due t o t h e in c r e a s e d
c a p a c i t y f o r t h e f u n g ic i d e s u s p e n s io n to s p r e a d a s a f il m i n t o th e
60
o p en f l o r e t s .
Im proved f o r m u la tio n s o f benom yl e . g . , e m u ls io n s , and
p e rh a p s b e t t e r m eth o d s o f a p p l i c a t i o n may im prove th e c o n t r o l o f e r g o t
o b ta in e d w ith t h i s c h e m ic a l.
A p p lic a tio n o f th e i n s e c t i c i d e d ia z in o n
d id r e d u c e i n f e c t i o n b u t n o t to th e e x t e n t t o make i t s u s e w o r th w h ile .
F or t h i s a s p e c t o f e rg o t c o n tr o l to be e f f e c t i v e , in s e c t c o n tro l o v er
a w ide a r e a w ould h a v e t o b e a c c o m p lis h e d .
W h ile n o n e o f th e c o n t r o l m e a su re s t e s t e d was e f f e c t i v e b y i t ­
s e l f , th e p o s s i b i l i t y e x i s t s t h a t a c o m b in a tio n o f o n e o r m ore o f them
m ig h t p ro v e to b e q u i t e e f f e c t i v e .
T h is w ould in c lu d e th e u s e o f
r e s i s t a n t o r t o l e r a n t germ p lasm ; th e u s e o f a v a r i e t y t h a t p ro d u c e d
t i l l e r s o v e r a v e r y s h o r t tim e p e r i o d ; th e u s e o f a good p o l l i n a t o r
to in s u r e r a p i d and c o m p le te f e r t i l i z a t i o n ; and th e u s e o f a s y s te m ic
f u n g ic i d e to p r o v id e p r o t e c t i o n d u r in g th e 1 0-15 d ay p e r i o d a f t e r
a n t h e s i s when th e h o s t i s m o st s u s c e p t i b l e .
The la c k o f th e n e c e s s a r y
germ plasm a t p r e s e n t h i n d e r s th e t e s t i n g o f t h e s e p o s s i b i l i t i e s .
SUMMARY
The s e r i o u s n e s s o f e r g o t c a u s e d b y C la v ic e p s p u r p u r e a ( F r . ) T u l.
i n m ale s t e r i l e b a r l e y and w h eat h a s p ro m p ted f u r t h e r s tu d y o f th e
b io lo g y o f t h i s p a th o g e n .
S eed co m p an ies a r e a n x io u s to p ro d u c e
h y b r id se e d i n th e same a r e a w here th e y w i l l b e p l a n t e d to k eep t r a n s ­
p o r t a t i o n c o s t s lo w .
O th e rw is e th e s e e d c o u ld b e p ro d u c e d i n d ry
c l i m a t e s , su c h a s A r iz o n a , w here e r g o t i s r a r e .
I t was n e c e s s a r y to
d e v e lo p a te c h n iq u e o f i n o c u l a t i o n to s c r e e n r e s i s t a n t v a r i e t i e s and
e f f e c t i v e f u n g ic i d e s w h ich w ould r e s u l t i n n e a r l y 1007. i n f e c t i o n o f
h e a d s and f l o r e t s .
T h is in v o lv e d th e rem o v al o f th e u p p e r 2 - 4 mm o f
th e t i p o f th e glum es fo llo w e d by i n o c u l a t i o n w ith a c o n i d i a l s u sp e n ­
s io n a p p l ie d w ith an a to m iz e r o r c a p i l l a r y t u b e .
I n o c u l a t i o n w ith
th e a to m iz e r was fo u n d t o p ro d u c e h ig h e r i n f e c t i o n l e v e l s th a n u s e
o f th e c a p i l l a r y tu b e .
S tu d ie s on th e e f f e c t . o f in o cu lu m d e n s i t y on
i n f e c t i o n r e v e a le d t h a t i n f e c t i o n c o u ld ta k e p l a c e w ith a s few a s 10
c o n i d ia p e r ml i n b a r l e y an d 1000 c o n i d i a p e r ml i n w h e a t, b u t maxim­
um i n f e c t i o n o c c u r r e d when 10^ o r m ore c o n i d i a p e r ml w ere u s e d .
S tu d ie s on t h e d u r a t i o n o f t h e i n f e c t i o n p e r i o d o f u n f e r t i l i z e d and
f e r t i l i z e d o v a r i e s i n d i c a t e d t h a t i n o c u l a t i o n d u r in g and s h o r t l y a f t e r
a n t h e s i s r e s u l t e d i n th e h i g h e s t l e v e l s o f f l o r e t i n f e c t i o n .
I n th e
c a s e o f u n f e r t i l i z e d f l o r e t s , s u s c e p t i b i l i t y d e c l in e d a t 10 d ay s and
was l o s t c o m p le te ly a f t e r 15 d a y s a f t e r th e i n i t i a t i o n o f a n t h e s i s .
F e r t i l i z e d o v a r i e s w ere s u s c e p t i b l e r i g h t a f t e r f e r t i l i z a t i o n .
A fte r
62
th e o v a r i e s had b e e n f e r t i l i z e d f o r 4 d a y s s u s c e p t i b i l i t y d e c re a s e d
u n t i l no i n f e c t i o n o c c u r r e d 9 d a y s a f t e r f e r t i l i z a t i o n .
A n a ly s is o f o v a r y w a sh in g s and honey dew e x t r a c t , i n d i c a t e d
t h a t b o th c o n ta in e d g lu c o s e and f r u c t o s e , w h ile o v a r y w a sh in g s a l s o
c o n ta in e d s u c r o s e and an u n i d e n t i f i e d s u g a r .
I t was fo u n d t h a t in
0 .1 M s o l u t i o n s o f t h e s e s u g a r s t h e c o n i d ia o f C. p u r p u r e a g e rm in a te d
w e ll b u t l i t t l e o r no g e r m in a tio n o c c u r r e d i n w a te r .
o v a r i e s was a b o u t 5 . 4 .
The pH o f young
A t pH 4 .6 and 5 .6 th e c o n i d ia o f
g e rm in a te d s i g n i f i c a n t l y b e t t e r th a n a t pH 6 . 6 .
C.
p u rp u re a
From t h e s e s t u d i e s
i t seem s t h a t i n w a te r on th e o v a r y s u r f a c e , th e s u g a r s e s s e n t i a l f o r
g e r m in a tio n w ould b e p r e s e n t in s u f f i c i e n t q u a n t i t y and a t a pH
f a v o r a b l e f o r t h e i r g e r m in a tio n .
P o is o n fo o d t e s t s w ere u s e d t o s c r e e n many m in e r a l o i l s , p erfu m e
o i l s , p r o t e c t i v e , and s y s te m ic f u n g ic i d e s f o r t h e i r a c t i v i t y a g a i n s t
—• Pu r P u r e a .
The e f f e c t o f some f u n g ic i d e s on g ro w th o f C. p u r p u r e a
was a l s o s t u d i e d .
Benomyl a t 10 ppm i n h i b i t e d g e r m in a tio n o f c o n i d ia
w h ile g ro w th was c o m p le te ly i n h i b i t e d a t 20 ppm.
Many o f th e s e
c h e m ic a ls w ere a p p l i e d to f i e l d grown m ale s t e r i l e b a r l e y .
Benomyl
a t 2400 ppm a p p l ie d t h r e e tim e s a t i n t e r v a l s o f 4 - 7 d a y s b e g in n in g
j u s t b e f o r e and d u r in g a n t h e s i s , g av e some c o n t r o l o f e r g o t s in c e th e
p e r c e n ta g e o f h e a d s and f l o r e t s i n f e c t e d was r e d u c e d .
To d e te r m in e
why benom yl d id n o t g iv e c o m p le te c o n t r o l v a r i o u s c o n c e n t r a t i o n s w ere
63
a p p l ie d to f l o r e t s w ith th e u p p e r p o r t i o n o f th e glum es rem oved
w hich had p r e v i o u s l y b e e n in o c u l a t e d w ith C. p u r p u r e a .
U sin g t h i s
te c h n iq u e f l o r e t i n f e c t i o n was re d u c e d from 947. t o 117. w ith 1000 ppm
benom yl and to 07. i f a w e t t i n g a g e n t l i k e T r i t o n X-77 and M u lti f ilm
B u f f e r X was u s e d a lo n g
w ith 1000 ppm
b en o m y l.
T h u s ,i f benom yl i s
t o g iv e good c o n t r o l o f
e r g o t , i t m u st r e a c h th e s u r f a c e o f th e o v a ry
a t o r b e fo re in fe c tio n ,
s in c e benom yl d o e s n o t a c t a s
an e r a d i c a n t
a g a i n s t t h i s p a th o g e n .
U nder n a t u r a l c o n d i t i o n s t h i s
i s v ery d if f i *
c u l t t o a c c o m p lis h , b u t d i f f e r e n t m ethods o f a p p l i c a t i o n and d i f f e r ­
e n t f o r m u la tio n s o f benom yl may i n c r e a s e i t s e f f i c i e n c y .
The u s e o f r e s i s t a n t germ plasm to c o n t r o l e r g o t was a l s o e x p l o r ­
ed i n m ale s t e r i l e w h e a ts .
W h ile t h e v a r i e t y C h r is d id h a v e some
d e g re e o f r e s i s t a n c e i n c o m p a riso n t o th e o t h e r v a r i e t i e s t e s t e d ,
m ore r e s i s t a n c e i s n ee d e d i f t h i s a s p e c t o f c o n t r o l i s to b e s u c c e s s ­
fu l.
W h ile n o n e o f t h e c o n t r o l m e a su re s t e s t e d was e f f e c t i v e by i t ­
s e l f , th e p o s s i b i l i t y e x i s t s t h a t a c o m b in a tio n o f o n e o r m ore o f
them m ig h t p ro v e to b e q u i t e e f f e c t i v e .
T h is w ould in c lu d e t h e u s e
o f r e s i s t a n t o r t o l e r a n t g erm p lasm ; t h e u s e o f a v a r i e t y t h a t p r o ­
duced t i l l e r s o v e r a v e r y s h o r t tim e p e r i o d ; th e u s e o f a good
p o l l i n a t o r to i n s u r e r a p i d and c o m p le te f e r t i l i z a t i o n ; and th e u s e
o f a s y s te m ic f u n g ic i d e to p r o v id e p r o t e c t i o n d u r in g th e 1 0-15 day
64
p e r io d a f t e r a n t h e s i s when th e h o s t i s m o st s u s c e p t i b l e .
The la c k
o f th e n e c e s s a r y germ plasm a t p r e s e n t h in d e r s th e t e s t i n g o f th e s e
p o s s ib ilitie s .
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2.
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Crop
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I *fch osyaips"1 17,71 u"Ivt*srTYumames
I