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Extension > Minnesota Crop News > Just the facts (Part 5): A review of the biology and economics behind insecticide recommendations

Thursday, July 21, 2016

Just the facts (Part 5): A review of the biology and economics behind insecticide recommendations

University of Minnesota: Bruce Potter, Robert Koch & Phil Glogoza
Iowa State University: Erin Hodgson
Purdue University: Christian Krupke
Penn State University: John Tooker
Michigan State University: Chris DiFonzo
Ohio State University: Andrew Michel & Kelley Tilmon
North Dakota State University: Travis Prochaska & Janet Knodel
University of Nebraska: Robert Wright & Thomas E. Hunt
University of Wisconsin: Bryan Jensen
University of Illinois: Kelley Estes & Joseph Spencer

Biology helps determine the profitability of crop production on your farm – Ignoring biology is expensive


None of what we have presented here is new, or groundbreaking information. However, all of what we have presented here is based on science that has been vetted and implemented over thousands of acres for more than a decade. Economic injury levels take commodity prices, labor and control costs into account. Fortunately, the biological components of an EIL are not sensitive to commodity or input prices. The insects on your farm do not eat faster or more when crop prices are high or insecticide costs are low; nor is your crop more sensitive to insect damage (remember the damage boundary). Yield loss occurs at the same level of pest population, regardless of market prices of commodities. It makes no sense to treat if there is no reasonable likelihood of damage.



Science is best when it does not sit still. New research on pest and crop biology and on new management tools may change EIL’s and associated ET’s over time. However, since the adoption of the 250 aphid/plant economic threshold, additional research has only confirmed the results of the original multi-state biological and economic research.

While some may view an insecticide costing "only a couple of dollars" as inexpensive when compared to other production inputs, it is still an added cost for no added benefit. These inputs add up with each acre applied. Farmers often find the "free" application costs when insecticides are tank-mixed with herbicides or other pesticides have unintended negative consequences - poor control from poor timing or application techniques of one or more products. Using an ET, based on sound, peer-reviewed research will help you apply your crop input dollars where they are most likely to produce a positive return on your investment and minimize the chances of creating other problems for yourself.

Using fear or faulty economic logic is tried and true as a very effective sales tool. It’s always prudent to be a skeptical consumer and consider the messenger when you evaluate information - a conflict of interest can arise if a profit motive underpins recommendations made without facts behind them. Be very wary of ETs that are based on "feel," eyewitness accounts, or other anecdotes that are not supported by hard scientific data. ETs that are radically different from those recommended by agricultural research universities are another red flag.

Hopefully, this article has provided you with information that will help you sort through the information clutter on TV, radio, print media and especially the internet. A list of research references is included in the complete article (http://z.umn.edu/soybeanaphidfacts) for those who would like to read and learn of some of the research supporting our soybean aphid management guidelines and economic threshold recommendations. Contact Extension for the most up-to-date and state-specific recommendations.

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