Initial Pesticide Certification Practice Test

Pesticide application efficiency is low—most of what is applied does not reach the target pests. A large portion is lost to drift as wind carries droplets away, evaporates from plant or leaf surfaces, degrades under sunlight or through chemical reactions in the environment, or runs off from treated areas into soil, water, or off-target surfaces. Because of these losses, only a fraction actually reaches the pest site or gets taken up by the plant for systemic products. Weather can influence how much is lost—factors like wind speed, droplet size, temperature, humidity, and rain can increase drift, volatilization, or wash-off—so conditions matter, but even under favorable conditions, you don’t get almost all of the applied product reaching the target. The important takeaway is that application efficiency is governed by many loss pathways, which is why good spray practices, equipment, and timing are essential to improve target delivery and reduce environmental exposure.