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Survey of pesticide applicators shows needs


Linda Geist
University of Missouri Extension
Phone: 573-882-9185

Published: Tuesday, July 12, 2016

Story source:

Mandy Bish, 573-882-9878

COLUMBIA, Mo. – Only 43 percent of Missouri pesticide applicators read the label each time they mix and spray.

That’s what more than 2,200 respondents say in a 2016 survey by University of Missouri Extension weed specialist Kevin Bradley.

That’s cause for concern, says MU researcher Mandy Bish. “Follow labels to reduce mistakes and waste, increase effectiveness and profits, and sustain a healthy environment,” Bish says.

Another 16 percent of respondents say they read labels half the time or less, and 1.2 percent of users admitted to never reading the label.

Read labels each time you apply, Bish says. Labels change. The Weed Science Society of America says the “label is not something you can glance at once and commit to memory.”

About 4 percent of surveyed applicators say they never check the wind speed or check it less than 50 percent of the time. When herbicides are applied at wind speeds higher than recommended on the label, they can be blown to adjacent fields and damage crops, ornamental plants and other vegetation.

Approximately 40 percent of applicators say their primary method of checking wind speed before spraying is looking at trees and other vegetation. At the 2016 MU Pest Management Field Day on July 7, Bish set up a box fan and placed a plant in front of it. She asked attendees to guess the wind speed. Mostly, the visual assessments were not accurate.

Most pesticide labels recommend spraying at wind speeds of 3-10 mph. Some labels may go as high as 15 mph.

Bish reminds applicators that speeds can be too low also. “Spraying in wind speeds under 3 mph is typically off-label as it may indicate temperature inversion.” This is where air temperatures near the ground are lower than the temperatures at higher altitudes, creating a stable air mass. When inversions happen, pesticide droplets linger in the stable air mass, where they may be moved by wind gusts to nontarget plants.

Nearly 24 percent said they consider 15 mph the cutoff point while 3.5 percent said over 20 mph was safe. Some said it depended on the chemical they were using and the use of surrounding land. Others said it depended on how far behind they were in getting their workloads accomplished.

Only 26 percent of respondents knew about FieldWatch, a specialty crop site registry. The free mapping program helps crop producers, beekeepers and pesticide applicators work together to protect specialty crops and apiaries. For more information, go to

Bish says handheld anemometers and wind speed tools give more accurate results than visuals.

She reminded pesticide applicators that there are smartphone apps and online tools to measure wind speed. These include MU’s real-time weather station reports at Missouri Mesonet,