Pennsylvania Corn, Soybeans: Pests Quiet, but Stay Vigilant

This time of year, when corn and soybeans are young and vulnerable, insect pest and slug populations can do their worst damage. Last season at this time, slug populations were thriving and many crop field suffered. Fortunately, this season has been a bit different so far. From my own observations in Central Pennsylvania, reports from county-based educators, and calls that I have received, pests are active but their populations seem relatively mild and they have not become too problematic yet.

Because of the lack of a dominant problem, I will just provide some commentary on a variety of pests that folks can consider when they are scouting their fields.

First, we are finding slugs in fields, but recent warmth, and many areas not receiving additional rain, seems to be slowing them down a bit. Nevertheless, we can find some damage (Figure 1), and in those parts of the state that have received rain frequently, the large slug populations in 2017 established a risk for similar populations this year. Therefore, if you have fields that tend to be sluggy and you have gotten regular rain, watch those fields closely for damage.

If damage shows, it often looks worse than it is, but be prepared to protect your crops with baits if stand establishment is in question. Refer to our fact sheet on slugs if you need more details about their biology or ways to manage their populations.

In addition to a general concern about slugs, we continue to capture low populations of black cutworm moth across the state. As mentioned in previous articles, our trapping network has detected only one significant flight of moths, and this occurred in Potter County, near Ulysses.

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The degree-day accumulation at that site is at 132, so our best estimate for when we would expect to see cutting damage in that part of the state will be early next week as our degree-day accumulation approaches 300 degree days. In other parts of the state, growers would be wise to walk their fields regularly to find any cutting damage because moths have not arrived in strong pulses this year. For more details on black cutworm biology and management, please refer to our Black Cutworm fact sheet.

Lastly, in small grains we have heard scattered reports of insect pests, including cereal leaf beetle larvae being found in wheat and oat fields, and some armyworms in wheat. We have not heard of large populations of these pests, but scout fields to determine how populations are developing in your areas. Scout these fields regularly for these pests, but hold off on applying insecticides unless you find economically damaging populations. Our fact sheets on the cereal leaf beetle provides key details.


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