2. http://mtpesticides.org Reeves Petroff Pesticide Education Specialist Montana State University Extension

3. How Chemicals Move Through Soil A Review How Water Moves Through Soil

5. Pesticide Characteristics Chemical characteristics of a pesticide will determine how it behaves in the environment. Four main characteristics: –Solubility –Adsorption –Half-life (aka. Persistence) –Volatility

6. Solubility Amount of chemical dissolved into a solution PPM > 30 ppm = high tendency to leach or runoff. Tordon = 400- 430 2,4-D = 890 Assert = 1370 Ally/Escort –1750 (pH 5) – 2790 (pH 7) –213,000 (pH 9) Paraquat = 7000 Roundup = 12,000 Which is the higher solubility? 50 or 500 ppm? 500 ppm Water soluble pesticides can move easily with water

7. Most lower solubility pesticides will bind more readily to clay and OM than those with higher solubility.

8. Pesticides in the Environment Environmental Fate of

9. What is Pesticide Environmental Fate? How and where a pesticide enters the environment How long it lasts Where it goes. BIOAVAILABILTY BIOCONCENTRATION BIOMAGNIFICATION

10. Fate Processes

11. Pesticide Losses at Application Method of application Rate Timing Number of applications Placement

12. Adsorption The binding of a pesticide molecule to a soil particle Clay & Organic matter!! More organic matter = more binding

13. Measuring Adsorptivity - K oc K oc Organic carbon partition coefficient - universal index How tightly a pesticide will bind to the organic matter in the soil.

14. Wet soils limit adsorption. Cool & dry is best for highly water soluble pesticides

15. K oc of Common Pesticides Banvel – 2 Stinger – 6 Pursuit – 10 Tordon – 16 2,4-D – 20 Assert – 35 to 66 2,4-D Ester – 100 MCPA – 110 Broadstrike - 700 Methyl Parathion – 5100 Lorsban - 6070 Treflan – 7000 Roundup – 24,000 Buctril – 10,000 Capture – 216,500 Paraquat – 1,000,000

16. Runoff vs. Leaching

17. Solubility & Adsorption Some things to ponder Read the label! –Look for restrictions based on soil type. Example – Tordon restriction on loamy sand to sandy soils. Calibrate! Calibrate! Calibrate! Do not over apply Know the soil type in the area you are spraying. Point vs. Non-point contamination

18. Soil texture has a big influence on leaching of pesticides

19. More adsorptive

20. Even a jar test will give you an idea!

21. Gravity has more influence on leaching in saturated soils In dry soils, capillary action influences movement

22. Degradation –Microbes near soil surface – more O 2 and nutrients –pH –Sunlight –Rate applied Expressed as “half-life.” Time required to degrade 50% of existing concentration Persistence (Residual)

23. Malathion - 1 2,4-D - 10 Banvel – 14 Ally, Amber – 30 Stinger - 40 Assert – 45 Roundup - 47 Tordon – 180 Spike - 360 Paraquat – 1000 Degradation values of some common pesticides (1/2 life in days)

24. Pesticide Drift Physical drift caused by small droplets –Improper nozzles –Improper pressure Chemical drift –Volatilization

25. Volatility Conversion of a liquid or solid to a gas Lower vapor pressure = lower volatility 2,4-D ester = high Banvel = high Banvel SGF = moderate Tordon = low Roundup = low

26. Volatility is also affected by: Weather –High temperatures 2x more 2,4-D ester volatilizes at 80 o than 70 o –Low humidity = more volatilization –Air Inversions

27. Protecting Water Resources

28. Protect Sensitive Areas! Aerial Spraying100 feet Vehicle Spraying 25 feet Hand Application 10 feet

29. Protecting Water Resources Practice IPM Environmental considerations Well Locations? Calibrate and use only what is needed Mix and load carefully Prevent back-siphoning Consider the weather Select, store and dispose of pesticides carefully

30. Protecting Water Resources Practice IPM Environmental considerations Well Locations? Calibrate and use only what is needed Mix and load carefully Prevent back-siphoning Consider the weather Select, store and dispose of pesticides carefully

31. Drift

32. Why Interest in Drift? Spotty Pest Control Wasted chemicals Off-target damage Higher costs - $$$ Environmental impact –Water and Air Quality Public more aware of pesticide concerns! (Negative) Spraying in more populated areas? (Suburbs)

33. Applicator Nozzle

34. WHAT IS DRIFT? Movement of.. spray particles vapors off-target Less effective control Possible injury to susceptible vegetation and wildlife.

35. DRIFT POTENTIAL BOOM HEIGHT HIGH PRESSURE SMALL DROPLETS Drift Production Movement

36. Comparison of Micron Sizes (approximate) 2000  m 850  m 420  m 300  m 150  m 100  m #2 Pencil lead paper clip staple toothbrush bristle sewing thread human hair

37. Driftability of Spray Droplets of Varying Sizes 10 feet Crosswind @ 3 mph 20  20  50  50  100  150   8 ft 22 ft. 48 ft. 178 ft. 1065 ft. 8 ft 22 ft. 48 ft. 178 ft. 1065 ft. \ HEIGHT OF SPRAY NOZZLES ABOVE TREATED SURFACES

39. Nozzle Drop Size Classes Very Fine to Fine < 200 um Medium to Coarse – 200 to 450 um Very Coarse > 450 um

40. 80 means 80 o fan 03 means 0.3 gallons per minute at 40 psi (38 ½ ounces per minute) 8003 tip

41. 87% reduction in drift prone droplets < 150 microns Low drift nozzle @ 0.2 gal/min flow rate - 40 psi Compared to 8002 Standard Flat-fan nozzle Low Drift Nozzles

42. Tip Spray Selection by Drop Size Turbo TeeJet Flat-fan

43. äTemperature & humidity ä Air movement (direction and velocity) äAir stability/inversions äTopography Weather and Other Factors Affecting Drift

44. Evaporation of Droplets Wind High Relative Humidity Low Temperature Low Relative Humidity High Temperature Fall Distance

45. Evaporation and Deceleration of Various Size Droplets* Droplet Diameter (microns) Terminal Velocity (ft/sec) Final Drop diameter (microns) Time to evaporate (sec) Deceleration distance (in) 20.0470.3<1 50.25171.83 100.913379 1501.75016 2002.4672925 *Conditions assumed: 90 F, 36% R.H., 25 psi., 3.75% pesticide solution 7 seconds for a 100 micron size droplet to evaporate at 90 o F at 36% RH

46. Strategies to Reduce Drift Avoid adverse weather conditions Buffer zones Consider using new technologies: –drift reduction nozzles –drift reduction additives –shields, electrostatics, air-assist Increase drop size Increase flow rates - higher application volumes Use lower pressures Use lower spray (boom) heights

47. Shielded Sprayers