Disease Susceptibility of Musk
Melon Varieties
Tom Turini - UCCE Imperial County
Plant Pathology Farm Advisor
Powdery Mildew of Melons
Podospora xanthii (formerly Sphaerotheca
fuliginea)
Damage
• Ripening may be premature or incomplete, which
results in poor flavor in melon.
Damage
• Ripening may be premature or incomplete, which
results in poor flavor in melon
• Severe mildew can kill leaves exposing the fruit,
which results in sunburn.
Dissemination
• Spores can be carried long distances by wind
currents.
• Thrips or other insects can spread spores
locally.
Conditions Favoring Powdery Mildew
Development
• Temperature - Optimum is 81 ºF.
Conditions Favoring Powdery Mildew
Development
• Temperature - Optimum is 81 ºF.
• Humidity requirement - Infection can occur at
RH of 46%, but disease is more severe under
more humid conditions.
CONTROL
• Plant resistance
• Fungicides
Imperial County Research
• Determination of P. xanthii race present at DREC
(Jim McCright in Spring and Fall 2002).
• Assess relative susceptibility of muskmelon
varieties to powdery mildew (in Spring 2001 and
2002).
General Methods
• DREC
• Seeded and irrigated in late March or early April
• Irrigation: drip
RACE DETERMINATION
Determination of P. xanthii race,
Spring 2002
• Ten varieties with different race susceptibility
characteristics were grown at DREC.
• Planted and irrigated on 21 March.
• Irrigation: drip
• Disease evaluation: 19 June
• Rating scale: 1 to 10: 1 has no visible mildew
and 10 is completely covered.
Determination of S. fuliginea race
Disease Rating
Iran H
9.0
Top Mark
5.0
Vedrantáis
4.5
PMR 45
1.0
PMR 5
1.0
WMR 29
1.0
PI 414723
1.0
MR-1
1.0
PI 124111
1.0
PI 124112
1.0
Rating scale – 1.0 to 10.0
Disease Reaction
S
S
R
R
R
R
R
R
R
R
Differential melon lines for races of P. xanthii
2
M e lo n lin e s
0
1
US
F ra n c e
3
4
Ira n H
S
S
nt
S
nt
S
V é d ra n ta is, T o p M a rk , A n a n a s
R
S
S
S
S
S
PM R 45
R
R
S
S
S
S
PM R 5
R
R
R
R
S
R
W M R 29
R
R
H
R
nt
S
E d isto 4 7
R
R
S
R
S
R
PI 414723
R
R
S
R
R
R
M R -1 , P I 1 2 4 1 1 2
R
R
R
R
R
R
Z
y
y
F r o m P it r a t e t a l. , 1 9 9 8 . T w o n e w r a c e s id e n t if ie d in 1 9 9 8 a r e n o t in c lu d e d ( H o s o y a e t a l. , 1 9 9 9 ) .
S = S u sc e p tib le , R = R e sista n t, H = H e te ro g e n e o u s, n t = n o t te ste d .
Determination of P. xanthii race,
Fall 2002
• Results suggested Race 3 was present
VARIETY TRIAL
Methods
• Experimental Design: Randomized Complete Block
• Replications: 4
• Plot Dimensions: 1 bed X 25 ft
Disease Severity Evaluation
• Evaluation dates: June 27, 2001 and 26 June 2002
• Sample size: Each of 10 leaves per plot were rated
• Rating scale: 0 to 5 based on percentage of leaf
surface covered with powdery mildew (0=no disease,
1=20%, 2=40%, 3=60%, 4=80%, 5=100%)
Variety Trial Results, 2001
Variety
Sol Real
Mary Gold
Sol Dorado
Cruiser
Emerald
Caravelle
Impac
Laredo
Morning Ice
Primo
RML 7923
Valley Pac
Mission
Saturno
Santa Fe
Goldmine
Gold Rush
Melon type
Declared resistance
Cantaloupe
Casaba
Cantaloupe
Cantaloupe
Honeydew
Cantaloupe
Cantaloupe
Cantaloupe
Honeydew
Cantaloupe
Cantaloupe
Cantaloupe
Cantaloupe
Honeydew
Honeydew
Cantaloupe
Cantaloupe
(race)
1&2
None
1&2
1
None
1&2
1&2
1
1
1&2
None
1&2
1
1
None
1
1
Powdery
mildew
severity (%)
27 June
0 d
1 bcd
1 cd
2 bcd
2 bcd
3 bcd
3 bcd
3 bcd
3 bcd
3 bcd
4 bcd
4 bcd
5 bcd
7 bcd
7 bcd
8 bcd
8 bcd
Variety Trial Results, 2001
Variety
Melon type
Declared resistance
(race)
Oro Rico
T-542
Gold Finger
Silver World
Hymark
Mega Brew
Golden Beauty
Powdery
mildew
severity (%)
27 June
Cantaloupe
Honeydew
Honeydew
Honeydew
Cantaloupe
Honeydew
1
None
None
None
1
1
9
9
9
9
10
11
bc
bc
b
b
b
b
Casaba
None
38
a
Variety
Trial Powdery
Mildew
Results,
2002
Cultivar (source)
Declared
Melon type
Powdery mildew
Mission (Asgrow)
Primo (Novartis)
Sol Real (Novartis)
Silver World (Know
You)
Emerald [OP honeydew]
Caravelle (Asgrow)
Cruiser (Harris Moran)
Hymark (Peto)
Impac (Asgrow)
Goldmine (Harris
Moran)
Esteem (Novartis)
(formerly RML 7923)
Mega Brew
Morning Ice (Harris
Moran)
Santa Fe (Peto)
Saturno
Honey Ace (Takii)
(formerly T-542)
Sun Canary (Know you)
Don Carlos (Seminis)
Gold Rush (Harris
Moran)
Laredo (Peto)
Oro Rico (Harris Moran)
Valley Pac (Asgrow)
resistance
1
1&2
1&2
None
Cantaloupe
Cantaloupe
Cantaloupe
Honeydew
None
1&2
1
1
1&2
1
Honeydew
Cantaloupe
Cantaloupe
Cantaloupe
Cantaloupe
Cantaloupe
0
1
1
1
1
1
C
C
C
C
C
C
None
Cantaloupe
1
C
1
1
Honeydew
Honeydew
1
1
C
C
None
1
None
Honeydew
Honeydew
Honeydew
1
1
1
C
C
C
None
Canary
Cantaloupe
Cantaloupe
1
2
2
C
C
C
Cantaloupe
Cantaloupe
Cantaloupe
2
3
3
C
C
C
1
1
1
severity (26 June)
0 C
0 C
0 C
0 C
Variety Trial Powdery Mildew Results, 2002
C ultiva r (sour c e )
G old en cren sh a w
G o ld e n B e a u ty
D e c la r e d
r e sista n c e
N on e
M e lon ty p e
C re n sh a w
C a sa b a
P ow d e r y m ild e w
se ve r ity (2 6 J un e )
28 B
53 A
Vine Decline of Melons
Monosporascus cannonballus
Perithecia
Monosporascus cannonballus
Perithecium and ascospores
Vine Decline Evaluation
• On 1 July, plots were rated on a scale of 0 to 10 for
vine decline symptoms. A plot rated 0 had no
collapsed vines or symptomatic leaves: a plot rated 10
would be completely collapsed.
Vine Decline Evaluation
• On 1 July, plots were rated on a scale of 0 to 10 for
vine decline symptoms. A plot rated 0 had no
collapsed vines or symptomatic leaves: a plot rated 10
would be completely collapsed.
• On 11 July, 3 roots were dug per plot. Roots were
rinsed in water and rated for M. cannonballus damage
on a scale from 0 to 10 based on percentage of root
system damaged.
Varietal Response to Vine Decline, 2002
(varieties with lower disease severity)
Variety (source)
Honey Ace (Takii)
(formerly T-542)
Golden crenshaw
Sun Canary (Know you)
Emerald [OP honeydew]
Esteem (Novartis)
(formerly RML 7923)
Morning Ice (Harris
Moran)
Santa Fe (Peto)
Saturno
Silver World (Know
You)
Golden Beauty
Mega Brew
Melon
Type
Honeydew
0.50
E
Root
symptoms
2 CD
crenshaw
Cantaloupe
0.75
0.75
1.25
1.25
E
E
E
E
2
1
1
2
CD
D
D
CD
Honeydew
1.75
E
1
D
Honeydew
2.00
2.00
2.25
E
E
DE
1
1
1
D
D
D
3.75
4.00
CDE
BCDE
1
2
D
CD
Canary
Honeydew
Honeydew
Honeydew
Casaba
Honeydew
Vine decline
Varietal Response to Vine Decline, 2002
(varieties with higher disease severity)
Variety (source)
Sol Real (Novartis)
Valley Pac (Asgrow)
Goldmine (Harris
Moran)
Hymark (Peto)
Impac (Asgrow)
Primo (Novartis)
Cruiser (Harris Moran)
Mission (Asgrow)
Oro Rico (Harris Moran)
Caravelle (Asgrow)
Gold Rush (Harris
Moran)
Laredo (Peto)
Melon
Type
6.00
6.00
6.50
ABCD
ABCD
ABC
Root
symptoms
6 AB
4 BCD
5 ABC
Cantaloupe
6.75
6.75
6.75
6.75
7.00
7.00
8.25
8.50
ABC
ABC
ABC
ABC
ABC
ABC
ABC
AB
4
4
3
5
7
8
5
5
BCD
BCD
BCD
ABC
AB
A
ABC
ABCD
Cantaloupe
8.75
A
6
AB
Cantaloupe
Cantaloupe
Cantaloupe
Cantaloupe
Cantaloupe
Cantaloupe
Cantaloupe
Cantaloupe
Cantaloupe
Cantaloupe
Vine decline
Summary
• There were mixed results regarding race, but Race 3
may be present.
Summary
• There were mixed results regarding race, but Race 3
may be present.
• Most entries had very low powdery mildew
incidence.
Summary
• There were mixed results regarding race, but Race 3
may be present.
• Most entries had very low powdery mildew
incidence.
• Golden Beauty Casaba and golden crenshaw (2002)
had high powdery mildew severity.
Summary
• There were mixed results regarding race, but Race 3
may be present.
• Most entries had very low powdery mildew
incidence.
• Golden Beauty Casaba and golden crenshaw (2002)
had high powdery mildew severity.
• Mixed melons had lower vine decline severity than
cantaloupes
Summary
• There were mixed results regarding race, but Race 3
may be present.
• Most entries had very low powdery mildew
incidence.
• Golden Beauty Casaba and golden crenshaw (2002)
had high powdery mildew severity.
• Mixed melons had lower vine decline severity than
cantaloupes
• Of the cantaloupe varieties, Esteem from Syngenta
(formerly RML 7923) had lowest vine decline
severity