[SANET-MG] pollution by herbicide spray drift

[jcummins <jcummins@UWO.CA>]

January 21, 2006

Prof. Joe Cummins

Pollution by Herbicide Spray Drift

Most of the genetically modified (GM) crops grown worldwide are designed 
to be resistant to chemical herbicides. The herbicide glyphosate 
(Roundup) is the most widely used herbicide used with herbicide 
resistant crops including soybeans, corn, canola and cotton. Glyphosate 
is a non-selective herbicide capable of damaging most food crops unless 
they are modified with a resistance gene. Spray drift may result from 
both ground and aerial spray applications but aerial application poses 
by far the greatest risk (!). Spray drift impacts both crop and non-crop 
plants causing both direct and subtle impacts such as damages to 
germination or seeds and growth characteristics of the plants (2). Lost 
of biodiversity has secondary impacts such as elimination of wildlife. 
Crops which are not genetically modified have frequently been damaged by 
spray drift. Cotton drift damage was simulated by studying damage at 
reduced glyphosate concentrations, levels as low as 70 grams per hectare 
(6.25% of the application rate for weed control) seven days after 
application of the herbicide (3). Rice and non-GM soybean plants treated 
with glyphosate , 140 grams per hectare, were found to have reduced 
yield (4,5). Such experiments show that the reduced level of glyphosate 
in spray drift causes crop damage and reduced yield at low 
concentrations of the herbicide.

The United States EPA reports that there are more than 2000 spray drift 
incidents reported annually to state regulatory agencies and insurance 
companies. Spray drift contaminates farmers crops and causing illegal 
residues or crop damage. Mitigation of spray drift damage was done 
primarily using better pesticide labeling product labeling and better 
training of applicators (6). EPA did not address the question is 
“aerial; spraying” really necessary. In the United States spray drift is 
regulated by States while labeling of the pesticide formulation 
including appropriate cautions is regulated by US EPA. States regulate 
pesticide spraying by outright prohibition or by prohibiting off site 
damage (7).

A recent court case in Ontario, Canada , Lockery versus Hayter before 
the Superior Court ,Justice Gordon Killeen presiding dealt with a spray 
drift incident in a clear and lucid manner,. The issues were discussed 
in a highly readable way making the decision available and 
understandable to the general public.” [1]This action, brought by a 
consortium of farm corporations against a neighboring farmer, is all 
about pickling onions. These are the small white onions, under an inch 
in size, which are used to garnish martini cocktails and luncheon and 
dinner spreads.

[2] Putting the plaintiffs’ case broadly, they claim that the 
defendants, in spraying their own soybean field with a powerful 
herbicide known as Roundup, allowed the herbicide to drift over onto the 
plaintiffs’ contiguous 75-acre onion field and cause serious damage to 
the plaintiffs’ crop for the 2000 year.”

The neighboring field was planted with glyphosate resistant soybeans 
which was sprayed with the herbicide on a windy June 23 an again on a 
windy July 21. The spray was visibly spread across field of onions 
which, unlike the soybeans, were sensitive and poisoned by the 
herbicide. The label instructions provided for the glyphosate 
formulation stated: “*APPLY THESE SPRAY SOLUTIONS IN PROPERLY *

* MAINTAINED AND CALIBRATED EQUIPMENT CAPABLE OF*

* DELIVERING DESIRED VOLUMES.*

* AVOID DRIFT – EXTREME CARE MUST BE USED WHEN*

* APPLYING THIS PRODUCT TO PREVENT INJURING *

* DESIRABLE PLANTS AND CROPS . *Do not allow spray mist to

drift since even minute quantifies of spray can cause severe damage or

destruction to nearby crop, plants or other areas on which treatment is

not intended, or may cause other unintended consequences. Do not

apply when winds are gusty or in excess of 8 km/h or when other

conditions, including lesser wind velocities, will allow drift to occur.

When spraying, avoid combinations of pressure and nozzle type that

will result in fine particles (mist) which are more likely to drift.”

It was clear that the product label had been neglected.

The defendant argued that the damage done to the onions was not caused 
by the herbicide but by water pooling on the soil and drowning the 
onions. The defendant was not only a farmer but also a drainage 
contractor and he claimed that the drainage he had installed in the 
field was actually faulty. The pooling claim was supported by a 
photograph taken March, 2002 well before planting could be undertaken 
.Since pooling appears in most fields during the spring runoff Judge 
Killeen was not swayed. The plaintiff was awarded $92,000 to reflect 
their actual loss.

The use of GM herbicide tolerant crops has given rise to two kinds of 
pollution. The first kind of pollution is genetic pollution of seed, 
food and feed. Such pollution results from spread of pollen or seeds by 
wind, animals or mechanical devices such as farm implements or trucks 
harvesting or transporting seeds such as maize, soybean, cotton or 
canola. The other kind of pollution is the drift of chemical herbicides 
used to control weeds in the tolerant crops.; The former pollution is, 
as yet , unresolved in terms of who is responsible for the damage . The 
latter pollution is further along in terms of resolution of the 
liability for negligent use of the chemicals but hampered by myriads of 
regulations. The two kinds of pollution should both be amenable to 
community based regulation but in no case has this been possible.

References

1,Lee,E, Burdick,C. and Olszyk,D. GIS-Based Risk Assessment of Pesticide 
Drift Case Study:Fresno County, California Office of Pesticide Programs 
Office of Prevention, Pesticides, and Toxic Substances U.S. 
Environmental Protection Agency

Washington, DC 20460 MARCH 2005 EPA/600/R-05/029

2. Blackburn LG and Boutin C. Subtle effects of herbicide use in the 
context of genetically modified crops: a case study with glyphosate 
(Roundup).

Ecotoxicology. 2003 Feb-Aug;12(1-4):271-85

3.Thomas,W,Burke,I,Robinson,W,Pline-Srnic, W,Edmistein,K,Wells,R and 
Wilcut,J. Yield and Physiological Response of Non-transgenic Cotton to 
Simulated Glyphosate Drift Weed Technology 2005,19,35-42

4.Kurtz,M and Street, J. Response of Rice (Oryza sativa) to Glyphosate 
Applied to Simulate Drift Weed Technology 2003, 17,234-38

5. Braverman, M. P. Simulated glufosinate drift on rice and soybean 
Proc.South. Weed Sci. Soc. 1998, 51:269

6. Ellenberger,J. Case studies on controversial drift problems pp 51-56 
Proc. North American conference on spray drift management D, Buckley 
editor 1998

7.Feitshans,T. Drift Laws pp 57-63 Proc. North American conference on 
spray drift management D, Buckley editor 1998

8. Ontario Superior Court of Justice Lockery versus Hayter Killeen,J 
presiding Court file No. 38006 Dec. 13 to 16, 2005 London, Ontario, Canada

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