Scout wheat early to beat pre-harvest intervals
Wheat producers should watch for significant fungal disease infestations in order to treat any problems in time to meet pre-harvest intervals, said a UNL specialist.
Pre-harvest intervals are listed on the labels of the various fungicides, said Stephen Wegulo, extension plant pathologist. Those intervals are determined by the Environmental Protection Agency to protect food items from dangerous chemical residues.
"If it's on the label, it's the law," Wegulo said.
For example, if the producer wants to apply a specific fungicide with a label that says, "Do Not Apply within 45 Days of Harvest," that application has to be timed at least 45 days before harvest.
Even though the fungicide would break down somewhat after harvest, there are no weather elements to help it biodegrade, so the chemicals would likely carry over into food products made from treated grain.
Most economically important plant diseases are caused by fungi, Wegulo said. Bacterial diseases like Goss's wilt in corn and black chaff in wheat are typically controlled by resistance rather than bactericide because bactericides are not cost effective.
Wegulo advised producers to check the labels of agricultural chemicals. Then, if questions remain, go to cropwatch.unl.edu and search for articles on fungicides. One update on fungicide use is at http://cropwatch.unl.edu/archives/2009/crop10/wheat_fungicide.htm .
Wegulo said that his pre-harvest interval advice for wheat producers applies to all other crop growers as well.
Extension is part of the University of Nebraska-Lincoln's Institute of Agriculture and Natural Resources.