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Organic Herbicides for Broccoli and Onions

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Selectivity of Organic Herbicides in Broccoli and Onions …

Selectivity of Organic Herbicides in Broccoli and Onions

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  • 1. Selectivity of Organic Herbicides in Broccoli and Onions Richard Smith Vegetable Crop and Weed Science Farm Advisor, Monterey County
  • 2. Comparison of Organic vs Conventional Broccoli and Onion Production Costs Production System Weeding Costs/A Organic1 $270 Conventional.2 $161 1 – Tourte and Smith, 2004; 2 – Smith et al. 2004 Hand weeding costs for onions can be extreme due to lack of cultivation and dense stands
  • 3. The waxy cuticle on cole crops and onions protects them to some degree from fertilizers and contact herbicides
  • 4. Conventional Materials Commonly Sprayed on Broccoli and Onions • Liquid fertilizers – AN20, NpHuric, Sulfuric Acid, Acid based fertilizers • Contact herbicides – Goal 2XL, Goal Tender, Buctril (onions) • These postemergence applications greatly reduce production costs • It seemed logical that postemergence applications of organic herbicides could be used in the same way
  • 5. Eco-Exempt 2-Phenethyl Propionate..................21.4.% Eugenol (Clove Oil)..........................21.4% Matran 2 [Matran EC] Clove Oil (46%) Other Ingredients (54%) (Water and Lecithin) [Clove Oil (50%) Other Ingredients* (50%) (Wintergreen Oil, Butyl Lactate, and Lecithin) ] AllDown Citric Acid 5% Acetic Acid, yucca extracts, and water 94.8% Garlic oil 0.2% Burnout II Clove Oil ...... 12% Sodium Laurel Sulphate ... 8% Other Ingredients: Vinegar, Lecithin, Water, Citric Acid, Mineral Oil 80% Weed Zap Clove Oil 30% Inerts including vinegar 70% [Clove Oil 45% Cinnamon Oil 45%] Weed-A-Tak eugenol (clove oil), 2-phenethyl propionate (peanuts), castor oil, thyme oil and wintergreen oil. Scythe* Pelargonic acid 4.2 lbs ae/gal 40% inert ingredients * To be reviewed by NOP in 2007 Adapted from Cheryl Wilen, 2006
  • 6. Other important considerations: Timing, weed species, weed size (< 2 true leaves)
  • 7. Postemergence Trials on Broccoli
  • 8. Number of Weeds in Broccoli 2006 Trial No. 1 140 120 100 80 60 40 20 0 Untreated Transplants, 1 vs 2 passes 10.80% Matran Rate 5.40%
  • 9. Hours Per Acre to Weed Broccoli 2006 Trial No. 1 35 30 25 20 15 10 5 0 Untreated 10.80% Matran Rate 5.40%
  • 10. Number of Weeds in Broccoli 2006 Trial No. 2 140 120 100 80 60 40 20 0 Untreated 5.00% Matran Rate 2.50%
  • 11. Hours Per Acre to Weed Broccoli 2006 Trial No. 2 70 60 50 40 30 20 10 0 Untreated 5.00% Matran Rate 2.50%
  • 12. Phytotoxicity Ratings 2006 Trial No. 3 6 5 4 3 2 1 0 Untreated Matran 5% Matran 2.5% Scythe 3% Scythe 1.5% Direct seeded, plants a bit old Treatments
  • 13. Yield – Number of Heads/Plot 2006 Trial No. 3 35 a 30 ab ab ab b 25 20 15 10 5 0 Untreated Matran 5% Matran 2.5% Scythe 3% Scythe 1.5% Treatments
  • 14. Scythe @ 1.0% Over the Top Directed Sept 18
  • 15. Scythe @ 1.5% Over the Top Directed Sept 18
  • 16. Scythe @ 2.0% Over the Top Directed Sept 18
  • 17. Scythe Over the Top 1.5% 2.0% Sept 18
  • 18. Scythe @ 1.0% Over the Top Directed Sept 26
  • 19. Scythe @ 1.5% Over the Top Directed Sept 26
  • 20. Scythe @ 2.0% Over the Top Directed Sept 26
  • 21. Broccoli Summary • The organic herbicides examined in these studies are not safe for over-the-top use on broccoli • Low rates of these herbicides can be used on broccoli if they are applied as a directed spray to the base of the plant • If too much of the material gets up onto the foliage it can cause significant phytotoxicity • If however, the material is successfully applied acceptable yields can be achieved.
  • 22. Onion Studies • Onions are different in that there is little opportunity for the spray material to be directed to the base of the plants • As a result, there is greater need for selectivity and careful selection of appropriate rates
  • 23. Untreated Matran @ 20%
  • 24. Matran EC @ 20%
  • 25. Matran EC @ 20%
  • 26. weed burn down and regrowth if weed is too big at time of application
  • 27. 2005 Dry Bulb Onion Evaluation Treatment Weed Control Percent Phyto Rating Weed Time hrs/A Untreated ---- 0.0 20.7 Yield 1000 Bulbs/A 139.8 Matran EC @ 20% 38.8 0.5 14.3 134.6 Goal Tender @ 0.125 lb* 82.5 2.3 5.4 139.3 * First true leaf
  • 28. Green Onion Trial
  • 29. 1st true leaf 2nd true leaf
  • 30. Shepherds Purse 1st true leaf 2nd true leaf
  • 31. Goal 2XL @ 1st true leaf untreated
  • 32. Matran @ 20%
  • 33. Scythe @ 5%
  • 34. 2005 Green Onion Trial Weed Control Ratings 9 8 7 6 5 4 3 2 1 0 Untreated Matran 20% 1st Matran 20% 2nd Scythe 5% Scythe 5% 1st 2nd Treatments
  • 35. 2005 Green Onion Trial Phyto Ratings 5 4.5 4 3.5 3 2.5 2 1.5 1 0.5 0 Untreated Matran 20% 1st Matran 20% 2nd Scythe 5% Scythe 5% 1st 2nd Treatments
  • 36. 2005 Green Onion Trial Yield – T/A 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 Untreated Matran 20% 1st Matran 20% 2nd Scythe 5% Scythe 5% 1st 2nd Treatments
  • 37. Size of weeds By 2nd true leaf 39 days after planting 2 days after 3% Scythe 2006 Dry Bulb Onion Trial
  • 38. Onion Summary • More effective weed control can be achieved if the organic herbicides can be applied at the first true leaf stage • However, we observed greater phytotoxicity on the crop when applied at this earlier growth stage • If applications go on too late and the weeds are too big, the low rates of organic herbicides will not be adequate to effectively control weeds.
  • 39. Other Applications for Organic Herbicides (Crazy ideas???)
  • 40. Mechanical Harvest
  • 41. Difficult, Tedious and Expensive to Hand Weed
  • 42. There may be opportunities to use organic Herbicides applications that are precision guided And that are hooded to take out some of the Weeds in this type of a situation
  • 43. The robotic system uses microjets These would lend themselves to organic materials
  • 44. Conclusions • Postemergence use of organic herbicides on broccoli and onions is a bit dicey. • Directed sprays on broccoli are very helpful to maintain safety • These trials indicate that there is hope for onions, but skill and good timing will be necessary to make this system work
  • 45. Conclusions • These organic herbicides may have a role in other ways in organic & conventional systems • They may feature in hooded spray operations and possibly in robotic weeding
  • 46. Acknowledgements • Cooperating growers – Chris Drew, Sea Mist Farms – Bob Martin, Rio Farms – Bill Peixoto, Dick Peixoto Farms – Jerry Rava, Rava Farms • Research assistants – Tiffany Bensen – Pat Headley – Dave Miltz.

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