Where did all the weeds go?
Identification of post-emergence herbicides
for use in native forb seed production
Shock, Feibert, Saunders, & Shaw
Identification of post-emergence herbicides
for use in native forb seed production
E. umbellatum, Sulfur-flower buckwheat
P. acuminatus, Sand penstemon
P. deustus, Hot rock penstemon
P. speciosus, Showy penstemon
L. dissectum, Fernleaf biscuitroot
L. triternatum, Nineleaf biscuitroot
Lomatium grayi, Gray biscuitroot
Identification of post-emergence herbicides
for use in native forb seed production
Post-emergence
treatment
Rate
lb ai/acre
Untreated
Buctril 2.0 EC
Goal 2XC
Select 2.0 EC +
Herbimax
Prowl H2O 3.8 C
Caparol FL 4.0
Outlook 6.0 EC
Lorox 50 DF
0.125
0.125
0.094 + 1% v/v
1
0.8
0.656
0.5
Identification of post-emergence herbicides
for use in native forb seed production
2006 seven post-emergence treatments and a check
A. 5-ft-wide plots perpendicular to the forb rows
B. 4 reps, randomized complete block design
C. Applied May 24 at 30 psi, 2.63 mph, in 20 gal/acre using
8002 nozzles, three nozzles spaced 20 inches apart
D. Plant injury rated visually on May 31, June 15 and 30.
2007
A. Same treatments, rates, methods, plots, and rates
B. Applied on April 24
C. Plant injury rated visually on May 1, 11, 25, and June 12
D. Seed of three species harvested as it matured.
Identification of post-emergence herbicides
for use in native forb seed production
2008
A. Same treatments, rates, methods, plots, and rates
B. Applied on March 12
C. Irrigated April 5-June 24, 1 inch every 2 weeks
D. Plant injury rated visually several times.
Seed of five species harvested as it matured.
2009
A. Same treatments, rates, methods, plots, and rates
B. Applied on March 20
C. Irrigated 1 inch every 2 weeks
D. Plant injury rated visually several times.
E. Seed of two species harvested as it matured.
Seed yield res ponse in 2008 to repeated a nnual pos
emergence he rbicides applied 2006, 2007, and 2008
Show y P.
Shar pl eaf
Sul f ur - F.
Ni nel eaf
Hot r ock
1200
Seed yield, lb/acre
1000
800
600
400
200
0
Ha n d Bu c tril Go a l Se le c t Pro wl Ca p a roOu
l tlo o k L o ro x
L SD (0 .0 5 )
Her bicide tr eatm ent
Identification of post-emergence herbicide
mixtures for use in native forb seed
production
Four species had been planted in the fall of 2006 for
more extensive herbicide screenings.
2008 and 2009:
• Tested rates and combinations of Prowl and
Outlook applied on March 12 (‘08) or March 20
(’09) plus Select applied later.
• Irrigated 1 inch every 2 weeks
• Plant injury rated visually several times.
• Seed was harvested as it matured.
Forb seed yield response to post-emergence
herbicides applied March 2008,
S howy P .
S har pleaf P .
S ulfur -F. B.
1400
Seed yield, lb/acre
1200
1000
800
600
400
200
0
Hand
Sel ect Pr ow l
Pr ow l
Pr ow l O ut l ookO ut l ook P + O
P + O
Her bicide tr eatm ent
P + O
P + O
P + O
P + O
Identification of post-emergence herbicides
for use in native forb seed production
Preliminary conclusions from 2007: Conclusions from 2008
and 2009.
A. In general there tended to be less observed foliar injury
with the use of Prowl, Outlook, and Select in 2006 and
2007. With early application, no foliar symptoms in 2008 or
2009.
B. Lomatium grayi and L. dissectum flowered in 2009.
C. P. specious and P. deutus resisted Prowl, Outlook, and
Select. P. deutus showed good seed yield. P. acuminatus
resisted Prowl and Outlook and demonstrated good seed
yield.
Identification of post-emergence herbicides
for use in native forb seed production
Preliminary conclusions from 2007: Conclusions from 2008
and 2009.
D. All species had foliar tolerance with no obvious symptoms
following early herbicide applications.
E. Five species had good seed yield and only Lomatium
triternatum had reduced seed yield when treated with
Buctril.
F. The rates and combinations of Prowl and Outlook were
applied on 4 species. They produced no foliar damage
systems and did not reduce seed yields for the three
species that had seed production.