WEED MANAGEMENT CONCEPTS: Developing Native Forb Seed Production Strategies. Corey Ransom

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1 WEED MANAGEMENT CONCEPTS: Developing Native Forb Seed Production Strategies Corey Ransom

2 Methods of Weed Control Preventative Biological Cultural Mechanical Chemical

3 Preventive Weed Control in Row Crops Clean equipment (planting, cultivating, harvest) Clean field borders Weed screens for irrigation water Prevention of weed seed production Spot treatment

4 Cultural Control Crop rotation Site selection Stale seedbed Seedbed preparation Proper planting date/depth/conditions/density Competitive varieties/disease resistant/vigor Disease and insect management Fertility management/placement Irrigation management Drip?

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6 Physical and Mechanical Control Preplant Tillage or Cultivation Preemergence Cultivation In Crop Cultivation Blind Cultivation Mulches Flaming (nonselective/selective) Handweeding

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8 Opportunities to innovate cultivation tools

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10 Hand weeding intra-row weeds Time consumption for hand weeding DIAS Crop Hour/ha Onion sown Carrot sown Sugarbeet sown Transplants 20-50

11 Chemical Weed Control Few herbicides that could currently be legally used to control weeds in native forb seed production. We need to identify and label herbicides that can be used to selectively control weeds in our forb seed crops.

12 Herbicide Selectivity Definition - a treatment that at a given dosage is toxic to some plant species but does not damage others.

13 Herbicide Selectivity Mechanisms (Physical): 1. Timing of herbicide application relative to crop growth (Roundup while crop is dormant) 2. Herbicide placement relative to: - Pattern of crop growth and development - Contact with plants (banding, drop nozzles)

14 Herbicide Selectivity Through Selective Placement Hooded band sprayer - can shield spray or plant - generally use herbicide that is not systemic Placement/Timing rs.com

15 Herbicide Selectivity Mechanisms (Physiological): 1. Differential absorption (includes retention) 2. Differential translocation. 3. Differential metabolism. 4. Differences in sensitivity at the target site.

16 Herbicide Selectivity Due to Plant Physiology Physiological differences in plant growth

17 Herbicide Selectivity Due to Plant Physiology Physiological Differences in plant growth Ex. Contact herbicides in perennial crops.

18 Objective Herbicides for Seed Production Identify herbicides for weed management in forb seed production. - Basalt milkvetch - Western prairie clover - Searls prairie clover - Tapertip hawksbeard

19 Initial Preemergence Herbicide Screen -50 seeds per flat. -50/50 Sandy Loam Soil with peat and vermiculite potting soil. -sprayed in chamber at 20 gpa. -Crepis stored at 34 F for 3 weeks. -evaluated 4 weeks after treatment. Species: - Basalt milkvetch - Western prairie clover - Searls prairie clover - Tapertip hawksbeard

20 Preemergence Herbicides and Rates Kerb 1.0 Treflan Prowl H 2 O 0.75 Outlook Sencor Plateau Olympus Chateau 0.047

21 Tapertip Hawksbeard Symptoms Kerb Sencor Treflan Untreated Olympus Prowl H 2 O Plateau

22 Basalt Milkvetch Symptoms Prowl H 2 O Outlook Olympus Treflan Sencor Kerb

23 Western Prairie Clover Symptoms Prowl H 2 O Outlook Treflan Untreated Olympus

24 Postemergence Herbicide Screening, 2009 Conducted on fields established in 2005 as transplants from conetainers. Plants were spaced 0.5 m. Herbicide treatments applied May 12, 15, and 21, Applications made with a shielded bicycle sprayer at 20 gpa and 30 psi. Multiple accessions and inconsistent plant vigor prior to treatment add to variability in these trials.

25 Herbicide Treatments on Basalt Milkvetch Herbicide Rates lb ai/a product Buctril pt 2,4-DB pt Transline pt Paramount + MSO lb Raptor + MSO oz MSO at 1.0% v/v Application made May 15. Injury evaluated May 26 (11 DAT) and June 23 (41 DAT). Biomass taken July 23.

26 Basalt Milkvetch Injury on May 23 and June DAT 41 DAT 50 Injury (%) Buctril 2,4-DB Transline Paramount Raptor Treatment Transline again caused significant season long injury 2,4-DB, Paramount, and Raptor had among the least injury

27 Milkvetch Plant Weight in Response to Herbicides 25 Biomass (g/plant) a b a b a a 5 0 Untreated Buctril 2,4-DB Transline Paramount Raptor Treatment Buctril and Transline significantly reduced plant biomass.

28 Millkvetch Flowering in Response to Herbicides a Flowering (plants/plot) ab bc bc bc c Untreated Buctril 2,4-DB Transline Paramount Raptor Treatment

29 Herbicide Injury in Basalt Milkvetch

30 Herbicide Treatments on Western Prairie Clover Herbicide Rates lb ai/a product Prowl H2O pt Outlook oz Goal lb Chateau + NIS pt Sencor + NIS lb Buctril pt 2,4-DB pt Transline pt Paramount + MSO lb Raptor + MSO oz Milestone oz Applied May 21. Injury evaluated May 26 (5 DAT) and June 25 (35 DAT). Plant biomass and seed head biomass August 6. NIS at 0.25% v/v MSO at 1.0% v/v

31 Western Prairie Clover Response to Herbicides Injury Biomass Herbicide 5 DAT 35 DAT Veg. Seed head % g/plot Untreated Prowl H2O Outlook Goal Chateau + NIS Sencor + NIS Buctril ,4-DB Transline Paramount + MSO Raptor + MSO Milestone

32 Herbicide Injury in Prairie Clover

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34 Impact of Application Timing No herbicide injury was evident in 2008 when applications were made while prairie clover was dormant. Significant injury appeared when actively growing prairie clover was treated in Issue of crop selectivity vs. weed efficacy.

35 Conclusions Seed Production 1. 2,4-DB warrants further investigation for postemergence use in basalt milkvetch. 2. Established western and Searls prairie clover appear to tolerate postemergence treatments of several herbicides, but impact on seed yield and viability has not been determined. 3. Transline and Milestone is too injurious for potential use. 4. Likely, the use of soil active herbicides will continue to cause minimal damage to established plants.

36 Herbicides That Could Have Great Utility 1. Graminicides Poast, Select, etc. 2. Preemergence herbicides used in established plantings - Prowl, Outlook 3. Preemergence soil active herbicides for establishment? 4. Postemergence herbicides Contact and Nonselective 5. Postemergence herbicides Selective

37 Where Do We Go From Here? Need to have herbicides registered for use in native seed crops. 1. Small acreage high value crops 2. Require Third Party indemnification label 3. Who will hold the label?

38 USDI BLM Great Basin Restoration Initiative, GBNPSIP, and USDA FS Rocky Mountain Research Station

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