Weed Resistance and Management Options

Transcription

1 Weed Resistance and Management Options Sustainable Ag Expo Nov 16, 2015 Kurt Hembree Weed Management Farm Advisor, UCCE, Fresno County cefresno.ucanr.edu

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4 Resistance vs. Tolerance: Resistance: The inherent ability of a weed to survive and reproduce following exposure to a dose of herbicide normally lethal to the wild type. (WSSA) The herbicide once worked at label rates, but now it doesn t. Tolerance: The inherent ability of a weed to withstand the specific effects of a particular herbicide. (WSSA) The herbicide never really worked before.

5 Types of resistance: Cross-resistance: possess one mechanism that can withstand herbicides from different chemical families. - A single point mutation in the enzyme acetolactate synthase (ALS) may provide resistance to the sulfonylurea and imidazolinone herbicide families. Multiple-resistance: possess more than one mechanism that can withstand herbicides from different chemical families. - In this case, herbicide options become very limited. Kochia scoparia population identified with target-site resistance to the PS II inhibitor herbicide, triazine, and to ALS inhibitor herbicides. Hairy fleabane in CA resistant to paraquat and glyphosate.

6 Mechanisms of resistance: Altered target site Enhanced metabolism Compartmentalization or sequestration Overexpression of target protein Altered translocation Gene amplification Target site is no longer susceptible to the herbicide.

7 How selection for resistance occurs:

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9 Weed biotype - CA Situation Herbicide family Year Common groundsel Asparagus PS II 1981 Perennial ryegrass RR, Roadside ALS 1989 Smallflower umbrella sedge Rice ALS 1993 California arrowhead Rice ALS 1993 Russian thistle Roadside ALS 1994 Wild oat Barley, Wheat Pyrazoliums 1996 Redstem Rice ALS 1997 Ricefield bulrush Rice ALS 1997 Late watergrass Rice ACCase and Lipid syn Rigid ryegrass Almond Glycine (glyphosate) 1998 Long-leaved loosestrife Rice ALS 2000 Barnyardgrass Rice ACCase and Lipid syn Early watergrass Rice ACCase and Lipid syn Littleseed canarygrass Onion ACCase 2001 Smooth crabgrass Rice Synthetic Auxins 2002 Horseweed T&V, Roadside Glycine (glyphosate) 2005 Hairy fleabane T&V, Roadside Glycine (glyphosate) 2007 Hairy fleabane T&V, Roadside Glycine (glyphosate) and Bipyridiliums (paraquat) 2009 Junglerice Corn, Alfalfa, T&V, Roadside Glycine (glyphosate) 2011

10 Other weeds escaping glyphosate: Palmer amaranth Sprangletop Lambsquarters

11 How do you recognize if herbicide resistance may be occurring? Label followed (rate, timing, additives, etc.); Loss of effectiveness at label rates observed over time; Small patches of escaped plants; Spray application done properly (coverage, gpa, calibration, etc.).

12 A Reality Check: Some weeds can spread a long distance, so resistant weeds may pop-up in your field even if you are on top of your weed game!

13 Maybe it s time to try something different?

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15 Strategies for proactive weed management: Keep the weeds susceptible Develop a plan and be willing to make changes as needed

16 1. Don t add to the seed bank: Weed Seeds/plant Horseweed/Marestail 1,000,000 Large crabgrass 150,000 Common lambsquarters 72,450 Common purslane 52,300 Barnyardgrass 40,000 Shepherd s-purse 38,500 Prickly lettuce 27,900 Hairy fleabane 10,000 Yellow foxtail 6,420 Wild oats 250

17 Follow-up with control of weed escapes, including borders, edges, and ditches:

18 2. Have a good spray operation: Sprayer performance Spray tip performance Rate(s) used Weed susceptibility Spray coverage issues Treatment timing Applicator skill and attitude

19 3. Refer to the label for guidance:

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21 4. Diversify the control tactics: Control tactic Herbicide rotation (MOA) Herbicide mixtures (MOA) Herbicide timing Herbicide uniformly applied Herbicide rate Mechanical primary Cultural irrigation type Cultural cover crops, mulching Potential impact Excellent Excellent Excellent Good to Excellent Good Fair to Good Fair to Good Poor to Fair

22 POST PRE + POST

23 50 Herbicide use in trees and vines in CA in 2010 (tree nuts, grapes, and stone fruits) 40 glyphosate Acres treated (%) oxyfluorfen, flumioxazin, carfentrazone, pyraflufen 65% WSSA MOA group number Source: CA DPR

24 Herbicides applied to wine grapes in % of total acres treated oxyfluorfen, flumioxazin, carfentrazone, pyraflufen glyphosate 65% Herbicide MOA Group Number (WSSA) Source: CA DPR SLO FC

25 Rotate and/or tank-mix MOAs (TNV) MOA Herbicide mode of action Herbicide Product Activity 1 Acetyl CoA carboxylase Select, Poast, Fusilade POST 2 Acetolactate synthase Matrix, Mission, Pindar GT (+14) PRE & POST 3 Microtubule assembly Surflan, Prowl, Treflan PRE 4 Synthetic auxin 2,4-D POST 5 Photosystem II Hyvar, Princep PRE 7 Photosystem II Direx PRE 8 Lipid synthesis EPTC PRE 9 EPSP synthase Roundup, etc POST 10 Glutamine synthase Rely 280, Lifeline, etc. POST 12 Carotenoid biosynthesis Solicam PRE 14 Protoporphyrinogen oxidase Chateau, Goal Shark, Venue, Treevix PRE & POST POST 15 Cell division Devrinol PRE 21 Cellulose biosynthesis Trellis PRE 22 Photosystem-I-electron diversion Gramoxone POST 27 Hydroxyphenylpyruvate dioxygenase Broadworks PRE & POST 29 Cellulose biosynthesis Alion PRE

26 Untreated Roundup (9) 30 DAT Roundup (9) + Rely 280 (10) 30 DAT Rely 290 (10) + Chateau (14) 30 DAT

27 Untreated Mission (2) + RU (9) + AMS + MSO Mission (2) + Chateau (14) + RU (9) + AMS + MSO Mission (2) + Alion (29) + RU (9) + AMS + MSO

28 UNT Broadworks (27) + Prowl H2O (3) Broadworks T. Lanini, (27) UC Davis + GoalTender (14) Broadworks (27) + Alion (29)

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30 cefresno.ucanr.edu

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32 Horseweed control across postemergence herbicides tested Parlier Control leaf Rosette 6-12" bolted Horseweed growth stage

33 In-row disking In-row plowing In-row mowing In-row tilling

34 French Plow Bezzerides Steam Greenmatch Dr. Anil Shrestha, Fresno State

35 Take-home points when considering weed resistance management: Be proactive by keeping weeds susceptible. Develop a plan and be willing to modify it as needed: 1. Do what you can to prevent weeds from going to seed. 2. Make sure the spray operation is up to par. 3. Refer to the label for helpful guidelines. 4. Diversify efforts (MOAs, treatment timing, cultivation, etc.).

36 Improvise, Adapt, Overcome Clint Eastwood Heartbreak Ridge