Pennsylvania: Soybean Aphids, Western Bean Cutworm Moths Showing Up

    Soybean aphid has begun colonizing Pennsylvania soybean fields. On 14 July, members of my research group found aphids in our research plots at Penn State’s research farm in Centre County.

    You may recall that between 2001 and 2009 large soybean aphid populations were a regular occurrence in our soybean fields, but for some unknown reasons they have not been arriving in strong numbers in recent years (I understand no one is complaining). In 2013, soybean aphid populations increased a bit in Pennsylvania, and some treated their fields. Because they were high last year, I expect them to be low in 2014.

    Recall a few things about soybean aphids.

    First, natural-enemy populations (lady beetles, minute pirate bugs, lacewings) in soybean fields usually suppress aphid populations, so avoid unnecessary insecticide applications to give the natural enemies a chance to contribute to control.

    Second, recall that research has revealed that the most important factor in efficiently and economically managing soybean aphid populations is treating fields at the right time: just when they reach the economic threshold of 250 aphids per plant. Treat earlier and money might be wasted; treat later and the effort might prove to be ineffective. This timing is far more important than the identity of the insecticide used.
    Lastly, remember that tank mixing insecticides with herbicides and/or fungicides is an inefficient way to attempt to control soybean aphids. Often the residual in these insecticide applications is not long enough to offer good control and the lower pressure used to apply the herbicide/fungicide does not provide the coverage needed for good insect control.
    We will continue to scout for aphids, and will report what we find. We should detect them in our soybean sentinel plot scouting efforts, which are reported elsewhere in this newsletter.Earlier in the summer, I mentioned that we are again monitoring populations of western bean cutworm across the state. Thus, far we have only captured a hand full of moths, so the populations might continue to be a minor concern for Pennsylvania corn and snap bean growers. We will continue our trapping until the end of August. For more information, on this so-far minor pest, visit our website.

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