Pesticide Drift and Phytotoxicity

1. Pesticide Drift and Phytotoxicity Stephen J. Toth, Jr. Wayne G. Buhler Department of Entomology Department of Horticultural Science North Carolina State University North Carolina State University Photograph from U. S. Department of Agriculture.

2. Pesticide Drift • Pesticide spray drift is “the physical movement of a pesticide through the air at the time of application or soon thereafter, to any site other than that intended for application” Doug Wilson

3. Two Types of Pesticide Drift • Airborne Drift: physical movement of spray droplets or granules from target site at the time of application; airborne drift is responsible for most damage • Vapor Drift: following application, pesticides can volatilize (change from liquid to a gas/vapor) and move from the target area; occurs when the pesticide is highly volatile and atmospheric conditions are suitable; vapor drift is the most difficult to control Ohio State University

4. Problems Caused by Pesticide Drift • Human Health: can result in pesticide exposure to farm workers, children and adults in nearby areas (i.e., homes, schools, day care centers, retirement centers, hospitals, parks, etc.) • Environment: can result in pesticide exposure to wildlife and their habitats Ken Hammond

5. Problems Caused by Pesticide Drift • Plants: can result in the contamination or destruction of agricultural crops, home gardens and ornamental plants by pesticide residues • Structures and Surfaces: can result in structural or surface damage to buildings and other property via corrosion, visible residues from pesticides Scott Bauer

6. Problems Caused by Pesticide Drift • Economic: can result in increased costs due to lack of pest control, wasted pesticide and repeat applications of pesticides; costly legal fees and fines and higher insurance premiums from damages • Legal: can result in illegal pesticide residues on crops and off-target sites Bill Tarpenning

7. Factors Affecting Pesticide Drift • Pesticide Formulation: dusts and wettable powders easily carried in air; granules and pellets are heavier and settle out of air • Particle Size: smaller droplets and dust particles drift farther than larger ones • Spray Pattern: use nozzles that produce narrower spray-fan angle USDA/ARS

8. Factors Affecting Pesticide Drift • Wind Velocity: air currents that cause drift are greater in middle of the day than in early morning or late afternoon; don’t apply pesticides when wind speed is less than 4 and greater than 12 miles per hour • Wind Direction: drift occurs downwind of pesticide application; make certain sensitive areas are not near and downwind of application Ken Hammond

9. Factors Affecting Pesticide Drift • Application Equipment: more pesticide drift results from air blast sprayers, high-pressure sprayers, ultra-low volume sprayers, high-pressure nozzles and small nozzle openings William Carnahan

10. Factors Affecting Pesticide Drift • Height of Sprayer: the greater the distance between spray nozzles (or boom) and the target, the greater the chance for pesticide drift North Carolina Pesticide Applicator Training Program

11. Factors Affecting Pesticide Drift • Volatility of Pesticide: vapors from pesticide move easily, occur more readily in hot, dry conditions • Temperature Inversions: cool layer of air trapped close to ground by a layer of warm air; results in less upward movement of pesticides which can drift laterally Ken Hammond

12. Factors Affecting Pesticide Drift • Pesticide Applicator: the good judgment, skill, experience, and planning of the applicator is a very important factor in preventing pesticide drift Do not fall into the trap of needing to spray RIGHT NOW! North Carolina Pesticide Applicator Training Program

13. How to Minimize Pesticide Drift 1. Read the pesticide label carefully for instructions on reducing pesticide drift 2. Survey the area to be sprayed and the surroundings to become aware of environmentally-sensitive sites, and make pesticide application decisions with these sites in mind 3. Know the wind speed and direction before applying a pesticide (do not spray when the wind speed is too high, a temperature inversion exists, or wind direction is toward a sensitive area) Gene Alexander

14. How to Minimize Pesticide Drift 4. Apply pesticides early in the morning or late in the after-noon, potential for drift is greater in the middle of the day 5. Choose the pesticide formulation and application equip-ment (i.e., sprayers, nozzles, etc.) that are least likely to cause drift 6. Use the largest spray droplets or granules possible 7. Keep the height of the sprayer as low as possible Tim McCabe

15. How to Minimize Pesticide Drift 8. Maintain an adequate buffer zone between the treatment area and pesticide-sensitive areas 9. Add drift retardant agents (i.e., thickeners that increase droplet size of pesticides) to pesticides when needed 10. Keep accurate records of all pesticide applications (including temperature, wind speed and direction, etc.), and evaluate results of past applications North Carolina Pesticide Applicator Training Program

16. Pesticide Phytotoxicity 2,4-D injury to cotton leaf • Phytotoxicity is injury to plants caused by exposure to pesticides NCSU Plant Pathology Department

17. Injury From Pesticide Phytotoxicity Paraquat injury to apple • Dead, burned or scorched spots on leaf tips • Russeting of fruit • Misshapen fruit, leaves or plants • Off-colored plants • Plant growth stunted • Delayed development or poor germination • Death of plant Marvin Williams

18. Causes of Pesticide Phytotoxicity • Excessive dosage of pesticide applied • Direct application of a pesticide to a susceptible plant • Drift of pesticide spray, dust or vapor onto plant North Carolina Pesticide Applicator Training Program

19. Causes of Pesticide Phytotoxicity • Runoff of pesticide from a treated field • Residues of persistent pesticide in soil • Use of an improper pesticide formulation Bob Nichols

20. Pesticide Phytotoxicity: Factors • Pesticide: chemical, solvents, concentration, formulation (EC formulations more phytotoxic than WP) Tim McCabe

21. Pesticide Phytotoxicity: Factors • Method of Application: mixtures of pesticides are more likely to cause phytotoxicity; high-pressure applications are more phytotoxic William Carnahan

22. Pesticide Phytotoxicity: Factors • Growing Conditions or Growth Stage of Plant: stressed or young, tender, fast-growing plants are more susceptible to injury James Baker

23. References • Applying Pesticides Correctly: A Guide for Private and Commercial Applicators. Unit 4: Pesticides in the Environment. pp. 43-44. • Ozkan, H. Erdal. 2000. Reducing Spray Drift. Bulletin 816-00. The Ohio State University Extension Service. (http://www.ag.ohio-state.edu/~ohioline/b816/index.html) • U. S. Environmental Protection Agency. 1993. Agri-cultural Pest Control - Plant Training Manual. pp. 27-29. • U. S. Environmental Protection Agency, Office of Pesticide Programs. Spray Drift of Pesticides. (http://www.epa.gov/pesticides/citizens/spraydrift.htm)