Unneeded/Excessive Pesticide Use?
Although my “title” is Plant Pathology Field Specialist, being the only Agronomy Extension staff person at the Winner Regional Extension Center, I deal with more than plant diseases. I consider that broader perspective to be a good thing, as there are often common themes across other aspects of agronomy.
A local producer recently brought in a “weed” that was present in his pasture, and more obvious in his neighbors’. With the aid of the SDSU Taxonomist’s expertise, the “weed” turned out to be a native wildflower. The Taxonomist knew the producer wanted to know what the “weed” was, mainly so he could find out which herbicide would control it. Being the expert in his field that he is, he provided the plant species, but also added a concern. In his words, “Native forbs like this one are being extinguished through wholesale herbicide application to grasslands. Native bees important for pollinating native and cultivated fruits, etc., are being decimated as natural nectar sources needed through the growing season are lost. I’m seeing far fewer bees and less fruit set in pollinator-dependent fruits in corn/soybean/pasture country here in the eastern part of the state. We have a pollinator crisis that is intensifying. I’m not a tree hugging true environmentalist, just an observant realist. How do we debunk the notion that anything not grass is a weed?”
This “theme” carries over to other areas. Entomologists promote that there are other ways to control insects than just insecticides. Wheat producers are likely hearing of aphids in their fields. There are also lady beetles and other predatory insects there too, and if at high enough populations, can keep aphid numbers below the thresholds. Applying insecticides when insect pest thresholds haven’t been reached may not be economical, and the predators will also be “controlled”. Insecticides are also not the only solution for alfalfa weevils. Granted, the weather doesn’t always cooperate to allow early cutting, and even so, the weevils sometimes survive to feed on the regrowth and justify an insecticide application. Alfalfa weevils have natural enemies and insecticides should be used with care to minimize the effect on these beneficials. There are situations where including an insecticide with another pesticide application because there are a few undesirable insects present may require coming back for another application because the beneficial insects were taken out in the first application.
A similar phenomena occurs with fungicides. In addition to killing harmful fungi, fungicides also kill good fungi. These good fungi help to control aphids, grasshoppers, and other insects as well as plant diseases such as bacterial. Extensive fungicide use has also shown to be detrimental to microbial activity in the soil.
Integrated Pest Management, or IPM, practices have been encouraged for several years. IPM principles stress crop scouting, following economic thresholds and considering alternative control methods. It’s important to recognize that a healthy grassland contains more plants than just grass, not all insects are pests, and not all fungi are bad.
6/27/2013 – Dakota Lakes Research Farm Tour, 4:00 p.m., 17 miles east of Pierre, SD
6/27-28/2013 – IPM Field School, Dakota Lakes Research Farm, 17 miles east of Pierre, SD
7/1/2013 – Winter Wheat Variety Plot Tour, 5:30 p.m. CDT, Jorgensen Farm, Ideal, SD
7/2/2013 – Winter Wheat Variety Plot Tour, 5:00 p.m. MDT, 5 miles east of Martin, SD
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