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  4. »eUpdate 771 October 25th, 2019»Insect activity update - Alfalfa, soybeans, and wheat

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Department of Agronomy

Kansas State University

1712 Claflin Rd.

2004 Throckmorton PSC

Manhatan, KS 66506

785-532-6101

agronomy@ksu.edu

Extension Agronomy

Insect activity update - Alfalfa, soybeans, and wheat


Alfalfa and Soybeans

Green cloverworm adults (Figure 1) have been very common in soybean and alfalfa fields the last couple of weeks, and this has caused concern about potential green cloverworm infestations next year. However, green cloverworm adults are, or have been, migrating to the southern U.S. for overwintering. Thus, since they do not overwinter in Kansas, infestations next year will depend on wherever the adults come back to, so predicting future infestations after overwintering adults return from the southern U.S. are not possible.

 

Figure 1. Adult green cloverworm. Photo by K-State Extension Entomology.

 

Alfalfa update – aphids and potato leafhoppers

Pea aphids are and have been returning, or at least increasing in numbers, to many alfalfa fields throughout north central Kansas (Figure 2). These are primarily cool weather aphids and are usually the last ones still feeding in the fall on alfalfa and the first ones in the spring.  However, with the onset of cool/cold weather, this late-fall feeding should be negligible. Potato leafhoppers (Figure 3), for the most part, have emigrated, or at least are not present in easily detectable numbers, so “hopper burn” (Figure 4) and its consequences, should not be problematic this fall/winter.


Figure 2. Pea aphids. Photo by K-State Extension Entomology.


Figure 3. Pea aphids. Photo by K-State Extension Entomology.

Figure 4. Example of “hopper burn”. Photo by K-State Extension Entomology.

 

Wheat update – armyworms and grasshoppers

Some fields have already established good stands of wheat this fall. However, there are also some pretty well established fields of volunteer wheat (Figure 5). There have been reports of armyworms and grasshoppers causing concern in some wheat fields that are struggling because of lack of moisture, but the recent cold weather should control both armyworm and grasshopper feeding.

 

Figure 5. Volunteer wheat stand. Photo by Jay Wisby, K-State Research and Extension.


 


Jeff Whitworth, Extension Entomologist
rwhitwor@ksu.edu