Strawberry Weed Management and Herbicide Update. Tim Miller WSU Mount Vernon, NWREC

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1 Strawberry Weed Management and Herbicide Update Tim Miller WSU Mount Vernon, NWREC

2 Common Weeds Ladysthumb Common chickweed Shepherd s-purse Henbit

3 More Weeds Common Lambsquarters Common Groundsel Pineapple-weed Annual Sowthistle

4 Still More Weeds Hedgemustard Powell Amaranth Italian Ryegrass

5 New Plantings Registered Herbicides United States Aim, Chateau, Dacthal, Devrinol, glyphosate, Poast, Prowl H2O, Select, Sinbar, and Spartan Established Plantings (fall/early winter) Aim, Chateau, Dacthal, Devrinol, Prowl H2O, Poast, Select, simazine, Sinbar, Spartan, and Stinger

6 Registered Herbicides United States Established Plantings (dormant) 2,4-D, Aim, Chateau, Prowl H2O, and Stinger Established Plantings (renovation) 2,4-D, Aim, Devrinol, Gramoxone, Poast, Prowl H2O, Select, simazine, Sinbar, and Spartan

7 New Plantings Registered Herbicides Canada Devrinol, Dual Magnum, Fusilade, glyphosate, Goal, Poast, Sinbar, and Treflan Established Plantings (fall/winter) Chateau, Dacthal, Devrinol, Kerb, Lontrel, Poast, Prowl H2O, simazine, and Sinbar

8 The Major Mode of Action in Strawberry Herbicides: PPO Inhibitors (Group 14) Includes Aim (US), Chateau (US), Goal (Canada), and Spartan (US) The herbicide binds to the enzyme protoporphyrinogen oxidase (PPO or Protox) which is involved in chlorophyll biosynthesis Once PPO is knocked out, singlet oxygen is formed, resulting in loss of pigments as well as rapid membrane destruction

9 The Grass Herbicides: ACCase Inhibitors (Group 1) Includes Fusilade (Canada), Poast (US and Canada), and Select (US) The herbicide binds to the enzyme acetyl-coa carboxylase (ACCase) which is involved in fatty acid biosynthesis Once ACCase is knocked out, fatty acids cannot be made, so cells cannot construct membranes

10 Strawberry Herbicides Inhibiting Microtubule Assembly (Group 3) Includes Prowl H2O (US and Canada) and Treflan (Canada) These herbicides inhibit the formation of the microtubule assembly necessary for separation of chromosomes during cell division Cells of young weed seedlings (especially in roots) are unable to divide normally, stopping plant growth

11 Strawberry Herbicides Mimicking Auxin (Group 4) Includes Stinger/Lontrel (US/Canada) and 2,4-D (US and Canada) While synthetic, these herbicides mimic the action of auxin, a naturally-occurring plant growth regulator Changes in the normal balance of auxin with other plant growth regulators, resulting in abnormal cellular division and differentiation and destruction of vascular tissues

12 Strawberry Herbicides Inhibiting Photosynthesis (Group 5) Includes Simazine (US and Canada) and Sinbar (US and Canada) The herbicide binds to the Q B binding niche on the D1 protein at Site A in the Photosystem II complex (PS II) Once the photosystem is knocked out, CO 2 fixation and ATP and NADPH 2 production is prevented Additionally, oxygen radicals are formed, resulting in loss of pigments as well as rapid membrane destruction

13 Strawberry Herbicides Inhibiting Very Long Chain Fatty Acid Biosyntheis (Group 15) Includes Devrinol (US and Canada) and Dual Magnum (Canada) The herbicide is absorbed by the plumule (emerging seed leaf) while still in the soil Weed seeds germinate normally, but in susceptible species the foliage fails to emerge from the soil

14 Strawberry Herbicide Trials Two trials each in 2014, 2015, and 2016 were funded by the Washington Strawberry Commission Established strawberry herbicide trial Newly-planted strawberry herbicide trial

15 Established Strawberry Trials

16 Established Strawberry Trial Totem strawberry transplanted in May, 2013, 2014, and 2015 Treated with Spartan + Chateau shortly after transplanting, and with Poast, Fusilade, or Select for grass control in June-May Roto-tilled several times during establishment, and once more prior to dormancy Herbicide combinations were applied in February, 2015 and January, 2016 Tested herbicides included: Registered: Chateau, Devrinol, Sinbar, and Spartan Nonregistered: Alion, Dual Magnum, Fierce, Trellis, Reflex, and Treevix

17 Established Strawberry Trial Crop injury and weed control monitored prior to berry harvest Berries harvested in May and June of each year (three to four pickings per plot) Total berry weight recorded and 50-berry average fruit weight calculated

18 Strawberry Injury % March, 2015 Alion Fierce Treevix Trellis

19 Weed Control % May, Alion Fierce Treevix Trellis

20 Berry Yield g/plot Alion Fierce Treevix Trellis None

21 Conclusions Established Strawberry Trials Strawberry injury in March, 2015 was high with Fierce and Treevix + Chateau Depending on the year, weed control was fair to excellent through harvest with most combinations Berry size and yield were fairly similar among treatments (2015 was a bad year ) Generally greater with Treevix or Trellis with Spartan or Sinbar Generally lower with Fierce combinations, Alion + Sinbar, Treevix alone or with Chateau or Devrinol

22 Newly-planted Strawberry Trials

23 Newly-planted Strawberry Trials Honeoye strawberries were transplanted in early June, 2015 and mid-may, 2016 Herbicides applied shortly after transplanting (POSTR) Registered herbicides were combinations of Spartan, Chateau, Devrinol, and Sinbar, Nonregistered herbicides were Reflex, Trellis, Fierce, Alion, and Dual Magnum

24 Newly-planted Strawberry Trials Crop injury and weed control monitored through the season Three plants per plot were collected and their total leaf area was measured in late August, 2015 and early September, 2016

25 Weed Control % July, Alion Reflex Treevix Trellis

26 Strawberry Leaf Area cm 3 August-September, Alion Reflex Treevix Trellis None

27 Conclusions Newly-planted Strawberry Trials Weed control was fair to good through the summer with several combinations, especially those with Alion and Trellis, as well as Reflex with Devrinol or Dual Magnum Strawberry leaf area was generally greater with Alion, Reflex, or Trellis with Devrinol, or with Trellis with Chateau or Dual Magnum

28 Many Thanks Funding for these strawberry trials were provided by the former Washington Strawberry Commission Norcal Nursery for plant material Herbicide manufacturers Carl Libbey, Yushan Duan, Wiharti Purba, Steve Seefeldt, and the gang at WSU Mount Vernon NWREC

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