herbicide drift –a view from the other side of the fence

Herbicide Drift – A view from the other side of the fence.

Roger Downer and Doug DoohanHorticulture & Crop Science, OSU

OHIO AGRICULTURAL RESEARCH AND DEVELOPMENT CENTER OHIO STATE UNIVERSITY EXTENSION

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OHIO AGRICULTURAL RESEARCH AND DEVELOPMENT CENTER

OHIO STATE UNIVERSITY EXTENSION

Particle Drift - the airborne movement of pesticide spray particles to non-target sites. Spraying during windy conditions, or using nozzles and pressures that result in the creation of fine spray droplets, increase the risk of spray particle drift.Vapor drift is the result of volatilization that can occur when pesticide surface residues change from a solid or liquid to a gas or vapor after an application of a pesticide. Once airborne, volatile pesticides can move long distances off site.

Spray Drift

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Primary causes of drift

• Poor application techniques (e.g., inappropriate nozzles, pressure, flow rate, boom height, forward speed)

• Unfavorable weather conditions. (e.g., high wind speed, low humidity, high temperature, temperature inversion)

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• Start with the nozzle. Use the coarsest recommended spray tip for the job you are doing.

• Use lower pressures.

• Keep the boom as close to the crop as is practical.

• Watch your speed.

• Spray when wind is not blowing toward sensitive vegetation.

• Application time (morning, evening or night? *)

Drift Management – things you can control.

* Early morning, shortly after sunrise, when wind speeds are low, is often considered to be a good time to spray but when overnight skies were clear and wind speeds are low it is often one of the worst times to spray due the likelihood of a temperature inversion. Late afternoon and evening inversions also occur and are also bad times to spray.

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• Wind speed (Too low (<4 mph*) or too high (> 15 mph))

• Humidity (low humidity = evaporation)• Temperature (high temp = evaporation

especially if humidity is also low).• Temperature Inversions**

Drift Management - things we can’t control but need to be aware of.

* Low wind speeds would seem to be ideal for pesticide application but are often indicative of a temperature inversion. Studies have shown that wind speeds of 4‐5 mph can exist in an inversion so unless an inversion can be shown not to exist be cautious when spraying in wind speeds < 4‐5 mph.

** To determine if an inversion exists temperature measurements should be made at two heights (6‐12 inches and 8‐10 ft) above the ground or closed crop canopy

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Oh! and just one more thing. • Weed-resistance (to glyphosate) problems are increasing.

• Row-crops with genetically modified (GM) tolerances to the herbicides 2,4-D and dicamba will be available to farmers to combat glyphosate-resistant weeds.

• Rapid adoption of these technologies is anticipated.

• Fruits, vegetables and nursery crops (specialty crops) are an integral part of diverse and healthy rural farm communities and often grow in close proximity to grain fields.

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Many specialty crop growers fear that these new GM crop technologies and

their industry cannot co-exist.2,4-D and dicamba tolerant-trait crops are unnecessary, will make farmers more dependent on the intellectual property held by large corporations, will injure sensitive non-target crops and landscapes, and will accelerate the evolution of herbicide resistance in weeds. (Johnson et al, Purdue Extension Bulletin ID-453-W).

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Indeed Steve Smith, Director of Agriculture for Red Gold stated in his Congressional testimony (9/30/2010)

“I am convinced that in all my years serving the agricultural industry, the widespread use of dicambaherbicide poses the single most serious threat to the future of specialty crop industry in the Midwest.“

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However!• Although older 2,4-D and dicamba formulations were both

notoriously prone to drift and to post-treatment volatilization, 2,4-D and dicamba have been used on millions of acres since the 1960’s and this has not resulted in widespread damage.

• New weed management approaches have been developed such as Dow AgroSciences Enlist™ Weed Control System that includes a new low-volatility formulation of 2,4-D with minimized drift potential, lower odor, and better handling characteristics than currently available 2,4-D amine or ester formulations.

• Risks associated with dicamba will be reduced through Monsanto’s Roundup Ready® Xtend Crop System and product stewardship programs..

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So why should we be concerned?• In Ohio as elsewhere, specialty crop producer’s farms are often

surrounded by farms that produce agronomic field crops. Herbicides used on these crops (e.g., glyphosate, 2,4-D, and dicamba) create an elevated risk for specialty crop damage from drift accidents.

• The use patterns of these herbicides will change and applications to corn and beans may coincide with the more susceptible growth stages of specialty crops. Changing weather patterns may also impact application timing.

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Accidents happen • Know the symptoms of 2,4-D and dicamba injury on your crops

and plan on scouting regularly during the time when grain growers are spraying.

• Early symptom detection within a few days of drift is important if you hope to detect residues of the causal agent – a data point of great value in obtaining compensation.

• Inform your neighbors about the high dollar value per acre of the crops you grow and of their extreme sensitivity to trace amounts of 2,4-D and dicamba.

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Spray drift of either 2,4-D or dicamba can induce severe injury in grapes that diminishes or even

eliminates crop value.

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Herbicide damage to tomatoes

glyphosate 2,4-Dhttp://www.cals.ncsu.edu/plantpath/extension/clinic/

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Consequences.• Specialty crops (especially grapes) are relatively small in acreage but

high in value.• Many are perennial crops and the consequences of drift damage can be

dire.

For example :-• Per-vine revenue losses : $9 (one year) to $51 (replacement) per vine• Estate wineries: With retail wine value, $96 (one year) to $400 per

vine (replacement).

http://northerngrapesproject.org/wp-content/uploads/2013/01/Martinson-2-4D-Presentation.pdf

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Prevention is better than cure• Compensation will be sought.

• We encourage open and frank communication between all parties.

• We encourage all specialty crop growers to register their fields with the Sensitive Crop Registry. http://www.agri.ohio.gov/scr/

• We strongly recommend all parties to keep records to help in any investigation.

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Useful Linkshttp://www.croplife.com/management/eight-keys-to-managing-spray-drift/

https://www.ag.ndsu.edu/pubs/plantsci/pests/ae1705.pdf

http://www.noble.org/ag/horticulture/reducingherbicidedrift/

https://www.ag.ndsu.edu/smallgrains/presentations/2013-best-of-the-best-in-wheat-and-soybean/robinson

http://elq.typepad.com/currents/2014/03/seq-chapter-h-r-1-damages-from-pesticide-spray-drift-under-trespass-law-terence-j-centner-introduction.html

http://www.extension.purdue.edu/extmedia/ID/ID-453-W.pdf

herbicide drift –a view from the other side of the fence

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