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dont start developing long- term management plans what we are seeing with European corn borer and farmers deci- sion to purchase conventional hybrids for a cost savings could end up costing them more in the end because of crop damage and yield loss. We advise growers to really tailor their product selections to the problems or insects they have in their field. There are options that allow for more flexibility when it comes to pricing. For exam- ple theres a price difference between structural refuge and integrated refuge she says. They are both good products that help to protect yield she shares noting that the integrated refuge is con- venient but the convenience costs a little more. In fields that have high insect pressure choose a product with multiple modes of action for above- and below-ground insects. In managing this years pests it is also important to think about what might be a problem next year. You need to understand whats going on in a field and plan accordingly. Every field is different and every operation has different needs she says. Thats how we as an industry need to think about helping growers address needs. In addressing needs for the 2016 growing season Ken Ostlie a University of Minnesota Extension ento- mologist says the first thing to consider when selecting a corn hybrid is yield potential. Bt traits only provide a yield benefit when targeted insects are above economic levels he says. When insect pressure is low any potential yield gains of newer trait- protected hybrids have to be balanced against their higher costs. A more important consid- eration may be limited avail- ability of high-yielding non-Bt or single Bt trait corn hybrids. Ostlie says pressure from corn borer might be higher in areas where significant amounts of corn without Bt corn borer traits were planted. Experts at Iowa State University report that when European corn borer is present its usually not the only pest. However he says risk can be reduced with scouting and applying a labeled insecticide where needed. To determine if treat- ment of European corn borer is economically justified John Obermeyer a Purdue University Extension entomol- ogist recommends using the following steps 1. Calculate preventable yield loss anticipated yield multiplied by yield loss figure from the table multiplied by the level of infestation multi- plied by the level of control. It is probably impractical to expect 100 percent control. A good estimate of control might be 75 percent he says. 2. Calculate preventable dollar loss per acre prevent- able yield loss multiplied by market value. 3. Compare preventable dollar loss per acre to the cost of insecticide application to determine if treatment is war- ranted. In the Corn Belt most growers have experienced light corn rootworm pressure. The other thing to remem- ber according to Tzafrir is that pests are not gone they need to be continuously scouted for and managed. In the case of corn root- worm she recommends assessing beetle populations in the fall which are a good indicator of what the pres- sure might be in the following growing season. She encourages those who work with growers to think about how to best manage for a three- to five-year period versus managing pests year- to-year. This is not so easy to do she says. If a farmer has high pressure this year next year could be different. Traits protect your invest- ment in genetics. You really want to protect the genetics and that means yield potential and profit potential. Syngenta started offering traits in 2004 and has since come a long way. DECEMBER 2015 SEEDWORLD.COM 59 Yield Losses Caused by European Corn Borers for Various Corn Growth Stages Percent yield loss number of borers per plant Plant Stage 1 2 3 Early whorl 5.5 8.2 10.0 Late whorl 4.4 6.6 8.1 Pre-tassel 6.6 9.9 12.1 Pollen shedding 4.4 6.6 8.1 Blister 3.0 4.5 5.5 Dough 2.0 3.0 3.7 These percentages are based on physiological stresses and do not include losses due to stalk breakage andor ear dropage. For more than 3 borers per plant use percent yield loss figures for 3 borers or adjust the loss slightly upward. Source Purdue University.