[Image: airplane spraying rice field]Herbicide drift often occurs when it seems the morning air is still and calm, according to Dr. Eric Webster, LSU AgCenter weed specialist.
Webster said just because it seems like no wind is present at ground level, however, doesn’t mean the same conditions exist a few feet above ground.
"The worst times are when the wind is 0 to 2 miles an hour," Webster said. "That’s when you get those inversion layers built up."
A field surrounded by tall vegetation increases the variation of wind direction, he said.
Using a ground rig is a good way to avoid drift problems, he said, although it still is not a guarantee.
Farmers can contaminate their own fields with unintended applications of herbicides if tanks are not properly cleaned, Webster said. "It’s always a good idea to triple rinse after spraying."
Using research plots, Webster and his associates are studying the effects of drift at different concentrations of herbicides.
Webster said Roundup and Newpath are the most likely materials to result in an inadvertent application.
Newpath drift often results in rice heads failing to emerge from the plant sheath, where they rot inside the plant, he said. The heads of a rice plant contaminated with Roundup often emerge but are sterile.
Webster is compiling material for a Web site to show symptoms of drift from different herbicides, and he is developing a pamphlet to help diagnose problems. He said both resources will be ready for the 2009 growing season. –Bruce Schultz
Checkoff funds for this project: $107,000