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Fungicide use on cornBy David G. Hallauer District Extension Agent Crops & Soils/Horticulture Over the years, fungicide use has increased, first in wheat, then in soybeans, and in 2007, more on corn than maybe ever before in Northeast Kansas. In some instances, the applications were more than justified. In others, they were maybe marginal at best. Four trials from the Northeast quadrant of the state showed that fields treated with a fungicide yielded little, if any, better than untreated checks in the same fields. There were some minor differences at some sites, and with solid commodity prices to back up applications, in some instances justified the treatment. For the most part, however, blanket fungicide applications likely wouldn't have paid. In fact, leaf disease occupied less than 5 percent of the leaf area at silk at most locations. With disease not increasing above the flag leaf until later stages, the fungicide wasn't as effective as had disease come in earlier. As we head in to the initiation of the tasseling stage, will it pay in 2008 to apply a fungicide to corn? Hard to say. What can be said is that fungicide applications are most likely to be needed on corn if the following apply: 1.) the hybrid is susceptible or intermediate to gray leaf spot or rust; 2.) the situation is corn on corn with high residue; 3.) leaf diseases are present; and 4.) weather conditions are warm and humid. Scouting is imperative. If you are interested in an economic evaluation of whether a fungicide is warranted, check out a spreadsheet at the KSU Ag Economics site at www.agmanager.info or contact your District Extension Office for a web address. A full summary of the 2007 corn fungicide results can also be obtained by contacting your District Office or dhallaue@ksu.edu. Spray bagworms now! Each year, many call concerned about when to spray bagworms. Consider this your heads up! Late June/early July is the typical control time frame, and appears to be holding true this year even with a cooler spring. This time period should have allowed for a good hatch up to this point that can result in good control measures. Control the first week of July isn't foolproof, though. If infestations during previous years was heavy, a second application may be a necessity. Use of the correct product is a must (contact your District Office for MF-728 which includes a product listing). Thorough coverage is required. Sometimes this can be the biggest challenge as large trees are more difficult to cover well with most hand sprayers. Scout now and take a close look to see how the hatch is going, then treat accordingly. Insecticide applications or hand picking are both appropriate and can lead to adequate control. 7/14/08 Date: 7/10/08
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