Weed Management Challenges in Vegetable Production
Ed Peachey Horticulture, OSU The Future of Weed s in Oregon
E. Peachey Horticulture Department Common themes
Weeds continue to adapt or introduce themselves The challenge of diversifying selection pressure The challenge of finding new tools Case studies Commodity coat tails ◦Sweet corn
Minor crop mire ◦ Brassica fresh processed and seed crops I. Weeds continue to adapt
Herbicide resistance • Kochia (Gly Res) • Horseweed (Gly Res) • Annual ryegrass Glyphosate ACCase inhibitors, 1987 (Poast, Select)
GR kochia in a sugar beet field
Photo courtesy of J. Felix New introductions
Palmer amaranth
‘Pollinator seed mix may contain Palmer amaranth weed’, WSU warns Photo courtesy of Capital Press Sept, 12, 2017 ‘New’ introductions
Velvet leaf in squash Velvetleaf 1928 Yamhill County, cottonseed from the south. 2002 Manure from poultry farms near Aurora. August 10, 2017
Velvet leaf seeds
•Notched •1/8 in dia •10 to 52% survival after 4 years
Bish and Bradley, U. Of MO Velvet leaf control with herbicides POOR CONTROL GOOD CONTROL Outlook Command Reflex Dual Magnum Chateau Reflex Spartan Eptam Treflan Cobra Raptor Basagran II. The difficulty of diversifying selection pressure INTEGRATED WEED MANAGEMENT IWM: Multi-tactic or Multiple-stress
1. Sanitation/ prevention 2. Mechanical 3. Biological 4. Cultural 5. Chemical A few weeds of one species survive
Selection Pressure and Weed Shifts Weed Shifts: Cost of reduced tillage
Yellow nutsedge A weed shift in row crops
Black nightshade Herbicide selectivity in table beets A unique individual of one species survives
Selection Pressure and Herbicide Resistance
A unique individual of one species survives
Selection Pressure and Herbicide Resistance Herbicide resistance in vegetable crops?
Annual ryegrass Glyphosate ACCase inhibitors, 1987 (Poast, Select) III. Challenge of Finding New Tools Herbicides o No new modes of action in 2 decades o Goldilocks herbicides: something that kills weeds but not too long o Finding supporting registrants o Engaging IR-4 (the minor crop registration program) Herbicide Screening
2018 23 herbicides 9 Brassicaceous, 6 other crops Two trials Reflex efficacy on green onion Supplements to herbicides? Cultivation Flame weeding Crop rotation Mechanical
Garford RoboCrop
Selectivity very good; dependent on accuracy of 34 February 25,positioning 2020 software
Yuma Grower Tour Jan 14 and 15, 2019 Text: 541-740-6712 Name and ‘Interested in Yuma tour” Flame weeding
Photo courtesy of
Selectivity dependent on emergence sequence of weeds and crops
February 25, 2020 37
Snap Bean Tolerance to Flaming Corvallis, 2018 12 5 gal/A 10 gal/A 11 Yield of check plot 10
9
8
7
Snap bean pod yield (t/A) pod beanSnapyield 6
5 12-8-4 % 30-24-15 % 44-37-32 % Percent of bean seedlings visible at flaming (total- hypocotyl extended-cotyledons unfolded)
Crop rotation Assumes there are crops to rotate to! Assumes rotation crop is not a weed in the next crop! Assumes there are different selection pressures that can be applied! The problem with crop rotations
Radish in squash Squash in beans Case Studies Crop classes and herbicide registrations Commodity coat tails ◦ Sweet corn, non transgenic (field corn) ◦ Snap beans (soybeans) ◦ Beets (sugar beets) Minor crop mire ◦ High value and risk crops ◦ Low acreage ◦IR-4 Minor Crops Program USDA Non-transgenic Sweet Corn Trends in Sweet Corn Production in OR (source: ODA)
Sweet Corn Acreage 10.1 tons/A (average) $95/ton 60000
50000 Total/A = $960
40000
30000 Acres
20000
10000 Total Sweet Corn Production 0 1955 1965 1975 1985 1995 2005 2011 500000 Year 450000 400000 350000 300000 250000
Tons 200000 150000 100000 50000 0 1955 1965 1975 1985 1995 2005 2011 Year Challenges in Sw Corn
Lots of herbicides labeled but….
• Cost!! • A little atrazine goes a long way • Pressure to apply Laudis/Impact (HPPD) late in season • Some varietal sensitivity to Laudis herbicides • Managing resistance to HPPD herbicides • MRL’s (Maximum residue limits) that limit use of HPPD herbicides INGREDIENT PRODUCT NAME Short-comings 1 2,4-D Formula 40 crop tolerance 2 Acetochlor Cadence ground water restrictions 3 Atrazine Aatrex 4l triazine resistance, water contam. 4 Bentazon Basagran poor efficacy 5 Carfentrazone Aim EC 6 Clopyralid Stinger plant back 7 Dimethenamid-p Outlook 8 Fluroxypyr Starane Ultra crop tolerance 9 Fluthiacet-methyl Cadet broadleaves only 10 Halosulfuron Sandea 11 Mesotrione Callisto 311 products 12 Nicosulfuron Accent crop tolerance 13 Pendimethalin Prowl H2O lodging 14 S-metolachlor Dual Magnum 15 Tembotrione Laudis no soil residual 16 Topramezone Impact, Armezon no soil residual
17 Pyroxasulfone Zidua crop tolerance 18 Thiencarbazone Capreno Herbicide + Laudis crop tolerance Why not genetic manipulation of sweet corn to improve weed control?
• Vast array of niche consumer markets • Trade barriers for PNW producers • ~600 commercial hybrids (here today and gone tomorrow) • Glyphosate and multiple herbicide-resistant weed populations are expanding at an alarming rate in other regions of the US 4- HHPD herbicides in corn
Mesotrione Callisto Topramezone Impact Tembotrione Laudis Bicyclopyrone in Acuron Tolpyralate Shieldex (ISK,7-27-17) Manuka oil (Tea Tree, NZ) Not registered or labeled oManuka tree oil contains leptospermone. oLeptospermone inhibits production of 4-HPPD o4-HPPD is needed for carotenoid synthesis oCarotenoids capture sunlight Bleaching symptoms Manuka oil Mesotrione (Callisto) is an analog of leptospermae Wild proso millet (in Super Sweet Jubilee, 2007) First year of use for HPPD herbicides Impact and Laudis 11.4 t/A
Impact + Outlook + Atrazine (Applied at V2) Untreated Corn sensitivity to 4-HPPD herbicides
Impact/ corn is very tolerant Armezone Laudis occasional symptoms includes safener Var. Captain Callisto Often causes injury Var. Merit + Bicyclopyrone ? Callisto Shieldex 400 SC now labeled AI: Tolpyralate ISK (Ishihara Sangyo Kaisha Corp) Distributed by Summit Agro partners (Helena and Tenkoz) 2012-17 OSU Evalautions Tolpyralate rates tested: 1 oz/A typical use rate 2/3 to 3.9 oz/A Insecticide interactions (Lorsban) 8 Varieties Corn varieties tested 2012-17
Variety Genetics Company GSS 1477 SH2 Rogers Basin R SH2 Seminis Devotion SH2 (white) Seminis Owatonna SH2 Harris Moran Coho SE Harris Moran SC 1263 SU Seminis Jubilee SU Rogers Captain SU Snowy River Seeds Weed control, var. Jubilee (SH2) Junction City, 2016
100 90 Alone 80 + Atrazine % 70 weed 60 control 50 40 30 20 10 0 Tembotrione Topramezone Tolpyralate Bicyclo Mesotrione (0.082) (0.022) (0.027) (0.023) (0.094) Laudis Impact Shieldex - Callisto July 18, 5 weeks after treatment
Impact Shieldex Weed control with 4-HPPD herbicides in sweet corn, Junction City, 2018
1 Laudis V4 3oz $ 15 98
2 Laudis + V4 3oz $ 19 83 Atrazine V4 1qt 3 Impact V4 1oz $ 20 93
4 Impact + V4 1oz $ 24 96 Atrazine V4 1qt 5 Shieldex V4 1oz $ 8 92 6 Shieldex+ V4 1oz $ 12 98 Atrazine V4 1qt Shieldex Control Carryover concerns?
Herbicide Half life (days) Impact/Armezon 14 Laudis 14 Callisto 5-32 Shieldex Tolpyralate ½ to 2.6 Carryover potential of 4-HPPD herbicides
Tall fescue + crimson clover
Planted July 7 Implication for interseeding Picture November 4 Adapted for Roundup ready systems 3 functions
Herbicide Fertilizer Replaced glyphosate with HPPD inhibitor HPPD inhibitor injury to red clover Applied post-plant surface
Laudis Impact (1/2x) (2x) 0.041 lb ai/A 0.054 lb ai/A
The Minor Crop Mire (fresh market vegetable and seed crops) "The trouble with being optimistic is that some people will think you're illiterate." Nothing has more strength than dire necessity
Euripides Playwright, Athens, Greece c. 484-407 Todays adaptation to Euripides
What doesn’t kill you…..
Makes you stronger Representatives in the PNW
Brassicaceous crops ◦ Broccoli, cabbage, cauli, etc Cucurbits Carrots Quinoa
Herbicides Labeled for Brassicaceae
Prefar Command Dacthal Outlook Prescription for Lorox nightshades and lambsquarters Goal Trans Trans Trans Devrinol Dual Magnum Trans Trans Spartan Trans Treflan Outlook Herbicide for Transplanted Radish for Seed
1800 1600 1400 1200
Lbs 1000 seed/A 800 600 400 200 0 16 16+5 32 32+5 Outlook (oz/A) Radish grown for seed oOutlook has a ‘tolerance’ for radish • Registrant not interested because of liability. Radish grown for seed o Stinger labeled on radish grown for seed o Stinger cannot be used on Daikon radish • Seed rule does not include seed that may be consumed (radish sprouts) Radish grown for seed o Starane • Crop safety must be demonstrated • Weeds oShepherdspurse oNightshade What will it take to make these options viable?
3rd party registrations?
Improve crop safety by applying activated charcoal Effect of activated charcoal on crop safety (% of normal growth)
Sulfentrazone '+ Charcoal 100 80 60 40 20 0 Crop Tolerance to Sulfentrazone Summary Weeds will continue to introduce themselves and adapt Solutions will continue to emerge for commodity-related crops Specialty vegetable crops …….. Questions? Comments? Questions?
The art of agriculture
2/25/2020