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Measuring Weather Issues for Pesticide Applicators Part 2

Measuring Weather Issues for Pesticide Applicators Part 2. by Linda S. Wiles Penn State Extension Educator. Using Climate Predictions. Long-term (seasonal)– to schedule crop species, cultivars Short-term (8-14 day, 6-10 day, 3-7 day) –

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Measuring Weather Issues for Pesticide Applicators Part 2

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  1. Measuring Weather Issues for Pesticide Applicators Part 2 by Linda S. Wiles Penn State Extension Educator

  2. Using Climate Predictions Long-term (seasonal)– to schedule crop species, cultivars Short-term (8-14 day, 6-10 day, 3-7 day) – to schedule irrigation, maintenance, pesticide applications See NOAA www.cpc.ncep.noaa.gov/products/forecasts

  3. Using NOAA Predictions • 6-10 Day Forecast • To schedule irrigation, fertilization, and chemical application • Recommended by Hu and Hubbard from University of Nebraska

  4. NOAA – Weather Conversions Temperature – 77Fahrenheit 25Celsius 298.15Kelvin Wind Speed – 9 mph 7.82 kt 4.02 m/s 14.48 km/h 13.2 ft/s 3 Beaufort Pressure – 29 inch mercury 982.05 milllibars 0.97 atmospheres 98205.25 pascals 982.05 hectopascals 1001.41 gm/sq.cm. 736.6 mm mercury 14.24 lb/sq.in

  5. Order of Weather Measurements 1st - Wind Direction 2nd - Wind Speed

  6. Wind Direction Recording Tips • Use compass to find magnetic direction - where wind comes from • Avoid steel objects while measuring - they may cause false readings • Use compass reading in degrees - not just N, S, etc.

  7. Compass Wind Direction Reading • Face the wind • Measure in degrees • Automatic calculation

  8. Wind Direction by Degrees 270 TO 360 0 TO 90 180 TO 270 90 TO 180

  9. Wind Speed Recording Tips • Hold unit so that it faces the wind • Measure for several seconds • Record at estimated height of spray (if possible) • Wind speeds increase with higher altitudes

  10. Compass Care • Check accuracy prior to field use • Protect from excess heat or cold (don’t leave in a vehicle) • Keep away from magnetic fields - belt buckles, knives, magnets, etc.

  11. Hand-held Wind Speed Reading Current Average Maximum • Current – check for gusts • Average – evens out gusts + calm – time based • Maximum – highlights problems - time based

  12. Temperature • Measure temperature at time of application • Avoid spraying in hot temperatures • Esp. in high humidity • If you must, use larger spray droplet size and lower equipment pressure

  13. Hand-held Temperature Reading • F air temperature in shade • Height of unit • Some include min/max

  14. Humidity Relative Absolute RealFeel Temperature patented Accuweather.com index

  15. Hand-held Humidity RH Reading • % moisture of air in shade • At high temperatures, air can hold more moisture • RELATIVE measure

  16. NOAA Calculators - RH Enter T and Dew Point in F or C 72F and 69F Dew Point  90.31% RH

  17. Combination Data Wind Speed + Temperature + Humidity ↓ Wind Chill Heat Index Dew Point

  18. Hand-held Wind Chill Reading • Measured in F • = temperature • >45F • <3 mph • Defined by US National Weather Service

  19. Wind Chill • Define: combines temperature + wind Where: T = air temperature in F, < 70F V= wind speed in mph data at 5 ft. height, clear night

  20. NOAA Calculators – Wind Chill • How to calculate Formula for WC (F) = 35.74 + 0.6215T – 35.75 (V0.16) + 0.4275T (V0.16) includes modern heat transfer theory

  21. Wind Chill • Why important Personal - Frostbite Plants - Frost Pockets

  22. Frostbite • In 30 minutes with calm wind at -5F • In 10 minutes with 35 mph wind at 0 to -5F • In 5 minutes with 45 mph wind at -15F

  23. Frost Pockets • Close to ground level, cold air trapped in low areas – possible 15°F lower than higher ground • Hand-held meters can track winter air inversions • Cold weather protections can be implemented • Reduced damage to fruit and landscape plants Caplan, 1988

  24. Hand-held Heat Index Reading • F air temperature in shade • = air temperature < 70F • Human comfort measure

  25. Heat Index • Define: combines temperature + humidity Where: T in F = ambient dry bulb temperature R = % RH [Canada’s Humidex uses dew point in K]

  26. NOAA Calculators – Heat Index • How to calculate Formula for HI (F) = -42.379 + 2.04901523T +10.14333127R – 0.22475541TR – 6.83783 x 10-3T2 – 5.481717 x 10-2R2 + 1.22874 x 10-3T+R + 8.5282 x 10-4TR2 – 1.99 x 10-4T2R2 Multiple Regression Formula with +1.3F; R.G. Steadman, 1979

  27. Heat Index • Why important Personal – Heat Disorders Plants – Increased Phytotoxicity

  28. Heat Disorders Heat Index Physical Response 80-90 F Lethargy 90-105 FSunstroke, Heat Cramps, Heat Exhaustion 105-130 FAbove, + possible Heat Stroke 130 F+ Above, + likely Heat Stroke If DIRECT SUN, add 15 F to HI

  29. Likelihood of Heat Disorders - NOAA • Caution -T > 80 F; any % RH • Extreme Caution -T = 82 F; 90% RH -T = 90 F; 40% RH • Danger -T = 86 F; 90% RH -T = 98 F; 40% RH • Extreme Danger -T = 90 F; 95% RH

  30. Hand-held Dew Point Reading • F air temperature in shade • DP ~ T humid • DP = T dew forms • DP = T <32F, frost forms

  31. Dew Point • Define: combines temperature + humidity Where: T in F = ambient dry bulb temperature R = % RH [Canada’s Humidex uses dew point in K]

  32. NOAA Calculators – Dew Point • How to calculate Formula for TD (F) Set x = (1 — 0.01 RH) where RH is expressed as a number from 1 to 100. Set T as temperature in C DPD is the difference between the temperature and dew point in C TD is the dew point temperature DPD = (14.55 + 0.114T)x + ((2.5 + 0.007T)x) to the third power + (15.9 + 0.117T)x to the 14th power TD [C] = T — DPD. TD [F] = (TD [C] × 9/5) + 32 Formula from Bill Murrell, Meteorologist, http://www.srh.noaa.gov/shv/Past_Questions_THREE.htm

  33. Dew Point • Why important Personal – more accurate estimate of human comfort than RH Plants – indicator for dew still present, disease issues

  34. Spray Equipment Selection IF full-coverage needed, as for contact herbicides, fungicides or non-systemic fungicides, THEN drift-resistant fan nozzles are not suitable.

  35. Inversion Conditions • 25-30°F or more night/day temperature difference • Clear skies + Calm winds previous night • Seasonally common spring and fall, possible year-round MA Dept Ag, 2003

  36. Record Conditions Weather conditions at the time of application should be listed on the pesticide application records.

  37. June 5 Weather Data

  38. July 6 Weather Data

  39. July 16 Weather Data

  40. Maximum wind for spraying • 9 mph • 15-16 mph • 25 mph

  41. Spray Pattern 3 Major Nozzle Patterns • Hollow or Full Cone Spray • Flat Fan Spray • Solid Stream Spray

  42. Hollow Cone Spray 0 mph 5 mph 0 mph post-app • Highly diffuse spray pattern at 0 mph • High potential for spray drift

  43. Hollow Cone Spray 0 mph 5 mph 0 mph 5 mph 9 mph 9 mph 13 mph

  44. Hollow Cone Spray Guidelines • Use for – shrubs + bushes • Rounded ring pattern • Finely atomized spray • Post-emergent herbicides, contact fungicides and insecticides

  45. Full Cone Spray Guidelines • Full Cone makes a filled in circle pattern • Primarily for broadcast spraying • Some banded applications

  46. Flat Fan Spray 0 mph 0 mph 5 mph 13 mph 9 mph 9 mph 0 mph post-app 5 mph post-app

  47. Flat Fan Spray – Post Application 0 mph 0 mph 5 mph 0 mph 5 mph 13 mph 9 mph 9 mph 13 mph 9 mph

  48. Flat Fan Spray Guidelines • Use for row treatment, systemic applications • Pattern is elliptical inverted V • Variations • Extended range – use for more pressures • Flooding – uses larger droplets • Even – non-tapered for band application

  49. Solid Stream Spray 0 mph 5 mph 0 mph 5 mph 9 mph 13 mph

  50. Solid Stream Spray 0 mph 0 mph 5 mph 5 mph 9 mph 9 mph 13 mph 13 mph

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