FORB RESPONSE TO HERBICIDES FOR
SEED PRODUCTION AND RANGELAND
RESTORATION
Corey Ransom
Objective – Seed Production
Identify herbicides for
weed management in
forb seed production.
- Astragalus filipies
- Dalea ornata
- Dalea searlsiae
Herbicide Tolerance Trials, 2011
Field trials at USU
research farm
Planted: 8 lb PLS/acre
Acid scarified and mixed
with corn hulls
Planter: Hege coneseeder
Plots size: 5 ft by 30 ft
replicated 4 times
Applications: CO2backpack sprayer, 20
GPA at 30 psi
Astragalus filipies -Basalt Milkvetch
Dry River germplasm
Dalea ornata - Western Prairie Clover
Aridlands germplasm
Postemergence Herbicides – Astragalus filipies
Herbicide
Rates
lb ai/A
product
2,4-DB
0.25
1.0 pt
2,4-DB
0.5
2.0 pt
Basagran + COC
0.5
1.0 pt
Buctril
0.25
1.0 pt
0.25 + 0.125
1.0 + 0.5 pt
Paramount + COC
0.248
5.3 oz
Pursuit + COC
0.047
3.0 oz
Raptor + COC
0.063
4.0 oz
2,4-DB + Buctril
Raptor + Basagran +
COC
COC at 1.0 pt/acre
0.063 + 0.25 4.0 oz + 0.5 pt
• Planted October 18,
2010.
• Treated June 21,
2011.
• Evaluated 36 days
after treatment.
Astragalus filipies injury and density change in
response to postemergence herbicides.
Treatment
Untreated
2,4-DB
2,4-DB
Bentazon + COC
Bromoxynil
2,4-DB + bromoxynil
Quinclorac + MSO
Imazethapyr + COC
Imazamox + COC
Imazamox + bentazon + COC
LSD (0.05)
COC at 1.0 pt/acre
Rate
lb ae/or ai/A
0.25
0.5
0.5
0.25
0.25 + 0.125
0.25
0.047
0.063
0.063 + 0.25
Evaluations 36 DAT
Density
Injury
reduction
_______________%_______________
0
21
1
29
9
29
8
29
30
36
14
37
19
42
8
19
7
28
13
26
14.7
NS
Challenges of plant
persistence appear to be
independent of herbicide
treatment!
Need to better understand
seedling survival.
Postemergence Herbicides –Dalea ornata
Herbicide
Rates
lb ai/A
product
2,4-DB
0.25
1.0 pt
Basagran + COC
0.25
1.0 pt
Buctril
0.25
1.0 pt
2,4-DB + Buctril
0.25 + 0.125
1.0 + 0.5 pt
Pursuit + COC
0.047
3.0 oz
Raptor + COC
0.063
4.0 oz
Raptor + Basagran + COC 0.63 + 0.25
4.0 oz + 0.5 pt
COC at 1.0 pt/acre
• Planted June 15, 2011.
• Application made August 19.
• Injury evaluated 22 days after treatment.
Dalea ornata injury, plant density increase, and
flowering in response to postemergence
herbicides.
Treatment
Untreated
2,4-DB
Bentazon + COC
Bromoxynil
2,4-DB + bromoxynil
Imazethapyr + COC
Imazamox + COC
Imazamox + bentazon +
COC
LSD (0.05)
COC at 1.0 pt/acre
Rate
lb ae/or ai/A
0.25
0.5
0.25
0.25 + 0.125
0.047
0.063
0.063 + 0.25
Evaluations 22 DAT
Density
Injury
increase
_______________%_______________
0
22
5
22
11
31
10
15
18
14
6
14
4
3
9
21
NS
NS
Flowers
no/plot
169
188
200
136
148
173
162
185
NS
Preemergence Treatments on Dalea ornata
Herbicide
Rates
lb ai/A
Product
Prowl H2O
0.5
1.1 pt
Prowl H2O
1.0
2.1 pt
Prowl H2O
1.5
3.2 lb
Outlook
0.75
1.0 pt
Nortron
1.0
2.0 pt
Several plots treated with Prowl H2O at 2.1 pt
for combination with postemergence
treatments
• Planted August 26,
2011.
• Sprayed August 27,
2011.
• Densities counted
October 13, 2011.
Dalea ornata plant densities in response to
preemergence applied herbicides following
August 26, 2011 planting.
Treatment
Untreated
Pendimathalin
Pendimathalin
Pendimathalin
Pendimathalin
Pendimathalin
Pendimathalin
Dimethenamid-p
Ethofumesate
LSD (0.05)
Rate
lb ai/A
0.5
1.0
1.5
1.0
1.0
1.0
0.75
1.0
Plant
density
no/plot
137
181
182
172
173
200
188
171
179
NS
Preemergence Herbicide Effects on Weed
Pressure, August 26, 2011 planting.
Untreated
Pendimethalin
1.5 lb ai/acre
Dimethenamid-p
0.75 lb ai/acre
Ethofumesate
1.0 lb ai/acre
Visible Injury from Preemergence Herbicides
on October 10, 2011.
Untreated
Pendimethalin
1.5 lb ai/acre
Dimethenamid-p
0.75 lb ai/acre
Ethofumesate
1.0 lb ai/acre
Conclusions of Herbicide Trials
• Astragalus filipies and Dalea
ornata appear to be tolerant to
several postemergence
herbicides.
• All preemergence treatments
caused visible injury.
• No herbicide treatments
reduced stand.
• Seed yield and viability needs
to be evaluated to demonstrate
herbicide utility.
Objective – Rangeland Restoration
Evaluate native species
response to herbicides
applied to control
downy brome.
How will they handle
exposure to these
herbicides after
seeding?
Initiation of Field Establishment Trial, 2009
Nephi, UT
Application timings:
Spring and Fall 2009
Herbicides:
Plateau 1, 2, 4, 6, 8, 10, and 12 fl oz
Olympus, Outrider, Matrix, Oust
Planting timings:
Fall 2009
Initiation of Field Establishment Trials, 2009
Species planted at Nephi:
Lupinus sericeus
Globe mallow
Sphaeralcea
Sulfur flower BW
Eriogonum umbellatum
Big blue penstemon
Penstemon cyaneus
Prairie clover
Dalea ornata
Searle’s Prairie Clover Dalea searlsie
Utah sweetvetch
Astragalus filipies
Silky lupine
Anatone
Bluebunch wheatgrass
Sherman
Big bluegrass
Basalt Milkvetch Establishment
8
Spring
Fall
Plants (no/plot)
6
4
2
0
16 .031 .063 0.94 .125 0.16 0.19
US DER RIX UST
0
.
P
0
0
0
0
O
T
T
T
M TRI
AT
T
T
T
T
A
A
A
Y
M
A
A
A
A
L
L
L
L
U
P
P
P
O
O
PL
PL
PL
PL
R
T
UN
Herbicide
Basalt Milkvetch Establishment
8
7
Plants (no/plot)
6
Spring
Fall
5
4
3
2
1
-0.05
0.00
0.05
0.10
0.15
Imazapic rate (lb ai/acre)
0.20
0.25
Conclusions
• Limited data demonstrates
that germination will be
influenced by herbicides
applied to control downy
brome
• A greater understanding of
individual species tolerance
and herbicide dissipation
rated in different soils are
needed
Support: Great Basin Native Plant Selection and
Increase Project
Silky Lupine Establishment
5
Spring
Fall
Plants (no/plot)
4
3
2
1
0
16 .031 .063 0.94 .125 0.16 0.19
US DER RIX UST
0
.
P
I
0
0
0
0
O
AT
T
T
T
AT AT
AT LAT LYM TR
M
A
A
A
L
L
U
L
L
L
L
P
P
P
O
O
P
P
P
P
R
T
UN
Herbicide
Grass ?? Establishment
25
Spring
Fall
Plants (no/plot)
20
15
10
5
0
16 .031 .063 0.94 .125 0.16 0.19
US DER RIX UST
0
.
P
I
0
0
0
0
O
AT
T
T
T
AT AT
AT LAT LYM TR
M
A
A
A
L
L
U
L
L
L
L
P
P
P
O
O
P
P
P
P
R
T
UN
Herbicide