University of Idaho Weed Science Update. Traci Rauch and Joan Campbell University of Idaho Plant, Soil, and Entomological Sciences

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1 University of Idaho Weed Science Update Traci Rauch and Joan Campbell University of Idaho Plant, Soil, and Entomological Sciences

2 Topics Grass weed control in wheat (pyroxasulfone) Rattail fescue Zidua, Anthem Flex Downy brome Anthem Flex Italian ryegrass Zidua, Anthem Flex Wheat tolerance Zidua irrigated winter wheat Anthem Flex winter, spring wheat varieties Broadleaf weed control in winter wheat Rattail fescue tillage management study

3 Background - Pyroxasulfone Mode of action Inhibits very long chain fatty acid synthesis -Group 15 Most active as preemergence herbicide Inhibits seedling growth, not seed germination Same group as flufenacet (Axiom= flufenacet/ metribuzin) and metolachlor (Dual Magnum) Controls Italian ryegrass and rattail fescue- also some broadleaf weeds (pigweed, lambsquarters, nightshade) Zidua (alone) and Anthem Flex (Zidua + Aim) Zidua and Anthem Flex registered in early 2014

4 Rattail Fescue Control in Winter Wheat Moscow, ID Zidua, Anthem, and Axiom preemergence combined with Everest, PowerFlex, and Maverick postemergence -turbo tilled and direct seeded Seeded to WB523/528 Sept 30 Postplant pre (wheat not germinated)- Oct 2 Spring application April 28 5 tiller wheat 2 tiller rattail fescue Crop injury was 2-11% with all preemergence treatments

5 Axiom, Zidua, Anthem and Fierce Combination Study Rattail Fescue Control 2015 Treatment % Control (Yield bu/a) Axiom - pre 92 (101) Zidua pre 82 (101) Anthem - pre 87 (99) Everest (2 tiller) 70 (88) PowerFlex (2 tiller) 45 (82) Maverick (2 tiller) 38 (88) Untreated check (75) All pre treatments were combined with Everest, PowerFlex, and Maverick. Rattail fescue control was 90 to 98% Population 15 plants/ft 2

6 Untreated check Zidua Zidua + Everest

7 Rattail Fescue Control in Winter Wheat Axiom, Zidua and Anthem preemergence alone did not adequately control rattail fescue (82-92%). Postemergence herbicides alone did not control rattail fescue. Everest better than PowerFlex and Maverick. Pre/post combination increased control 90-98%. Rattail fescue control will need pre Group 15 herbicides combined with post Group 2 herbicides.

8 Downy Brome Control in Winter Wheat Moscow, ID Anthem Flex preemergence combined with Everest or PowerFlex postemergence- conventional system Seeded to Ovation Oct 7 Postplant pre (wheat not germinated) Oct 9 Spring application April 10 2 tiller wheat 2 tiller downy brome No crop injury

9 Downy Brome Control in Winter Wheat 2015 Treatment % Control June 11 Anthem Flex - pre 94 Anthem Flex (pre) + Everest (3 tiller) 98 Anthem Flex (pre) + PowerFlex (3 tiller) 99 Everest (2 tiller) 60 PowerFlex (2 tiller) 94 Population 4 plants/ft 2

10 Downy Brome Control in Winter Wheat Anthem Flex alone controlled downy brome 94% in conventional tilled system and with a low downy brome population. PowerFlex was a better postemergence herbicide than Everest for downy brome control.

11 Italian Ryegrass Control in Winter Wheat with Anthem Flex Moscow, ID Anthem Flex at 2 timings alone and combined with PowerFlex and Osprey Preplant - October 2 (rain Oct 11) Seeded October 14 WB523/528 Postplant preemergence (wheat not germinated) Oct 16 (rain Oct 23) Postemergence April 27 and May 7 Wheat 2 and 3 tiller, I. ryegrass 3 leaf and 1 tiller No winter wheat injury

12 Italian Ryegrass Control in Winter Wheat with Anthem Flex Treatment Rate (oz/a) Timing % Control Anthem Flex 3.75 (1.75) preplant 99 Anthem Flex 4.5 (2) preplant 93 Anthem Flex 3.75 postplt pre 95 Anthem Flex 4.5 postplt pre 99 Anthem Flex + PowerFlex Anthem Flex + Osprey preplant 3 tiller (60) postplt pre 2 tiller (67) Population 3 plants/ft 2 PowerFlex and Osprey resistant biotypes suspected 90 96

13 Italian Ryegrass Control in Winter Wheat with Zidua Moscow, ID Zidua alone and in combinations Seeded October 14 WB523/528 Postplant preemergence wheat not germinated October 14 (rain Oct 15) Delayed preemergence 1 inch radicle - Oct 24 (rain Oct 29) Postemergence April 27 Wheat 2 tiller; Italian ryegrass 3 leaf No winter wheat injury

14 Italian Ryegrass Control with Zidua in Winter Wheat Treatment Rate (oz/a) Timing % Control Zidua 1.5 (1.3) postplt pre 88 Zidua 3 (2.6) postplt pre 98 Zidua 1.5 delayed pre 88 Zidua 3 delayed pre 99 Axiom 10 delayed pre 81 Axial XL 16 2 tiller 16 Population 12 plants/ft 2 Axial XL resistant Italian ryegrass biotypes suspected

15 Italian Ryegrass Control Application rate more important with pyroxasulfone than timing in winter wheat Both application timing and rate of pyroxasulfone are important in spring wheat (weed germination in progress - moisture present) Pyroxasulfone good fit for Italian ryegrass control. Group 15 so will be able to control ACCase and ALS resistant populations.

16 Topics Grass weed control in wheat (pyroxasulfone) Rattail fescue Zidua, Anthem Flex Downy brome Anthem Flex Italian ryegrass Zidua, Anthem Flex Wheat tolerance Zidua irrigated winter wheat Anthem Flex winter, spring wheat varieties Broadleaf weed control in winter wheat Rattail fescue tillage management study

17 Winter Wheat Tolerance to Zidua with Irrigation University of Idaho Parker Farm In conventional system with spring barley October 3, 2014 Ovation winter wheat seeded Zidua applied at 0, 2 and 4 oz/a Sprinkler irrigation applied at 0, 1/3, 2/3, and 1 inch (Each irrigation amount had an untreated check)

18 Winter Wheat Tolerance to Zidua with Irrigation Treatment Rate Irrigation Injury Yield oz/a inch % bu/a Zidua (135) Zidua Zidua 2 1/ (139) Zidua 4 1/ Zidua 2 2/ (128) Zidua 4 2/ Zidua (131) Zidua

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20 Picture of irrigated injury

21 Picture of irrigated injury

22 Spring Wheat Varieties Tolerance to Anthem Flex University of Idaho Parker Farm Spring wheat varieties Eden, Whit, Hartline, and Glee Spring barley Champion (sensitive crop) Anthem Flex applied day of seeding at 1X (3 oz/a) and 2X rate No visual injury present entire growing season Yield and test weight for the treated varieties did not differ from each varieties untreated check

23 Winter Wheat Varieties Tolerance to Anthem Flex University of Idaho Parker Farm Winter wheat varieties Boundary, Brundage96, Cara, and Silver Winter barley Eight-twelve (sensitive crop) Anthem Flex applied day of seeding at 1X (3.5 oz/a) and 2X rate Eight-twelve (winter barley) - Injury and 39% reduction in yield with Anthem Flex Winter wheat -Yield and test weight for varieties did not differ from each untreated check

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25 Impacts of Zidua and Anthem Flex Crop Response Studies Zidua can safely be applied to winter wheat under worse case scenario situations (precipitation immediately after application in an adequate amount) at 2X rate. Anthem Flex can safely be applied to some winter and spring wheat varieties at 2X rate.

26 Topics Grass weed control in wheat (pyroxasulfone) Rattail fescue Zidua, Anthem Flex Downy brome Anthem Flex Italian ryegrass Zidua, Anthem Flex Wheat tolerance Zidua irrigated winter wheat Anthem Flex winter, spring wheat varieties Broadleaf weed control in winter wheat Rattail fescue tillage management study

27 Background - Bicyclopyrone Mode of action HPPD inhibitor -produces essential compounds for carotenoid pigments -Group 27 Active as a pre and postemergence herbicide Destruction of chlorophyll, plant turns white and dies (bleachers) Same group as pyrasulfotole (Huskie) and mesotrione (Callisto) Activity on broadleaf weeds c. lambsquarters, catchweed bedstraw, mayweed, p. lettuce Currently registered in corn Acuron (4 a.i.). Wheat herbicide bicyclopyrone/bromoxynil Label in 2017

28 Prickly Lettuce Control with A19278 in Winter Wheat Treatment Rate (oz/a) 2014 (%) 2015 (%) A A A Huskie Starane Flex Density (plt/ft 2 ) Application info inch diameter p. lettuce, 2 tiller wheat April application inch diameter p. lettuce, 6 tiller wheat April application

29 Mayweed Chamomile Control with A19278 in Winter Wheat Treatment Rate (oz/a) 2014 (%) 2015 (%) A A A Huskie Starane Flex Density (plt/ft 2 ) Application info inch mayweed, 2 tiller wheat April application inch mayweed, 3 tiller wheat April application

30 2014

31 2015

32 Rattail Fescue How much tillage does it take?

33 Impact of Rattail Fescue Tillage Management Study Herbicides in winter wheat are the only research-based tool for rattail fescue control Increase cultural control knowledge with crop rotations and tillage type and duration

34 Rattail Fescue Tillage Management Study Fall 2012 Seeded rattail fescue at 2 locations Fall 2013 Seeded Brundage 96 w. wheat in October, no rattail fescue control Fall 2014 Initiated tillage treatments Spring 2015 Seeded spring wheat (crop rotation s. wheat/spring pea/w. wheat)

35 Rattail Fescue Tillage Management Study Year 1 Year 2 Year 3 Direct Seed Direct Seed Direct Seed Disc Direct Seed Direct Seed Disc H Harrow Direct Seed Disc H Harrow H Harrow Chisel Direct Seed Direct Seed Chisel Chisel Direct Seed Chisel Chisel Chisel

36 Disc Notill Chisel

37 Rattail Fescue Tillage Management Study Each plot was split into two herbicide treatments and an untreated check Herbicide treatments were applied parallel to the tillage treatments Herbicide treatments: Zidua (preemergence) at 1.5 oz/a Zidua (pre) 1.5 oz/a plus Everest (postemergence) 1 oz/a Plant counts, yield, and test weight

38 Results Rattail Fescue Tillage Study No-till untreated checks have the highest rattail fescue populations at Moscow and Genesee Rattail fescue populations were reduced by herbicides in the no till treatment Untreated > Zidua > Zidua + Everest Rattail fescue populations were reduced by tillage No-till > Disc = Chisel At Moscow, spring wheat yield was increased by increased tillage Chisel > Disc > No-till

39 Questions?