Chapter 22

Question 1

What is the difference between pesticide drift and overspray?

Answer 1

overspray - when pesticide is directly applied outside of the target area (always avoidable)

drift - when air currents cause pesticide to be deposited outside of a target application site. can occur as solid or liquid particles, or as vapors

Question 2

What problems can arise because of pesticide drift?

Answer 2

can damage nontarget plants, contaminate surface water, harm wild/domesticated animals and people

violates the label

Question 3

What is the difference between spray drift and vapor drift?

Answer 3

vapor drift occurs when a volatile pesticide changes from a solid or liquid to a gas and resulting fumes move from the target area

spray drift occurs when small spray droplets are carried by air movement from the target area

Question 4

What are 5 factors that increase drift and why?

Answer 4

droplet size decrease - smaller droplets fall more slowly and are more easily moved by the wind

wind speed increase - stronger wind means droplets will be carried further before being deposited

temperature increase - water in spray droplets evaporates faster in warm air. this makes the droplets smaller

humidity decrease - has a similar effect on evaporation as a temperature increase

distance from nozzle to target increase - the farther the droplet must travel the longer it will be in the air and subject to effects of wind

Question 5

What are the most important factors affecting spray drift?

Answer 5

spray droplet size is the most important factor affecting potential for spray drift. Wind speed is also very important. However increasing droplet size can greatly reduce the winds effect

formulation and physical properties impact spray drift but are much smaller than those of droplet size, wind speed, and distance from nozzles

Question 6

What are the effects of air stability on spray drift?

Answer 6

air stability - during the heat of the day air warmer at the soil rises rapidly and may set up air currents that can life even larger spray droplets. (better to spray in early morning or evening)

perfectly calm air can promote drift as well because droplets remain suspended in the air for longer. middle unstable air is best

Question 7

What clues suggest the presence of a temperature inversion?

Answer 7

ground fog or smoke that layers and moves laterally instead of moving upward and rapidly dissipating. usually occurs on clear, calm nights and lasts into the morning

Question 8

How can you reduce the risk of drift when applying a pesticide indoors?

Answer 8

turn fans and air conditioners off, close vents

use low volatile or non volatile pesticides and low pressure treatments

Question 9

What factors increase spray drift and vapor drift?

Answer 9

same as spray drift.
anything that decreases droplet size
temperature - volatility increase with temp
soil conditions - wet soils increase volatilization

Question 10

What is the first rule of drift management?

Answer 10

know when not to spray

Question 11

What site condition should you consider before deciding to spray?

Answer 11

weather - wind, temperature, inversion
sensitive area - know the distance between site and downwind sensitive areas
sprayer set up - how fine or coarse a spray you will be using and nozzle height

Question 12

How do you asses the risk of drift?

Answer 12

asses the risk of drift and its consequences.
how likely is it for drift to cause adverse effects? what pesticide you are using? label can have information about applying the pesticide under certain conditions

consequences to yourself, plants, neighbors if drift occurs

Question 13

How can you widen the window of opportunity for spraying ?

Answer 13

early pest detection - scouting and monitoring
flexible ipm plan - give you a wider range of pesticide choices
buffer zones - around a site will increase the distance between the target area and a sensitive site

Question 14

2 main considerations for reducing drift

Answer 14

keep the nozzle as close to the target surface as possible

apply coarsest droplet size spectrum that provides sufficient coverage and pest control

Question 15

What are the factors that affect the proportion of small droplets in a pesticide spray ?

Answer 15

spray pressure - increase the number of small droplets produced (keep pressure as low as possible)
nozzle - larger openings or narrower angles will produce fewer fine droplets
spray rate - higher spray rates let you use nozzles with larger openings

drift reduction agents reduce the number of small spray droplets

sprayer selection and nozzle selection

Question 16

what are the advantages of boom sprayers over arblast sprayers?

Answer 16

drift is less likely with boom sprayers because they produce larger spray droplets, release them closer tot he target, and direct them downward rather than laterally

Question 17

what factors affect the droplet size spectrum?

Answer 17

Spectrum of droplet size based on different nozzle pressure combinations. you can ensure that you will produce the coarse spray possible that will still provide adequate control and coverage

Question 18

How can solid particles drift?

Answer 18

pesticide dust or soil particles can move from the target area in air.

Question 19

how can you reduce solid particle drift?

Answer 19

consider wind speed and direction. avoid applying dusts in high wind.
close all windows of nearby building
indoors turn off fans, air circulation equipment

Question 20

what are the effects of temperature inversion on spray drift?

Answer 20

occurs when a layer of warm air is sandwiched between layers of cold air. an inversion is cause by rapid cooling of the soil and/or crop surface. lost heat radiates upwards causing the air above the surface to be warmer.

Think of smoke going straight into the air vs getting traped and moving laterally in concentrated clouds.

Question 21

what pesticides pose the highest risk of vapor drift

Answer 21

volatile herbicides - dicamba, clomazone