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Posted 16 June 2020. PMN Crop News.


First Emergence of Soybean Gall Midge in Cass County, Nebraska


Source: Nebraska Extension CropWatch Article. http://plantpathology.unl.edu/


Justin McMechan, Crop Protection and Cropping Systems Specialist, University of Nebraska-Lincoln | Tom Hunt, Extension Entomologist, University of Nebraska-Lincoln | Robert Wright, Extension Entomologist, University of Nebraska-Lincoln | Débora Montezano, Entomology PhD Student, University of Nebraska-Lincoln | Vilma Montenegro | Taynara Possebom


Lincoln, Nebraska (June 11, 2020)--On June 10th, 2020 three soybean gall midge adults were collected south of Louisville, Nebraska (Fig. 1). This was the only site in the network with soybean gall midge adult activity. You can continue to follow adult emergence at all locations through soybeangallmidge.org. Cages are being checked daily in east-central Nebraska.

 

For soybean growers near the site with activity (Fig 1) and that have had issues with soybean gall midge, they can consider making an application in the next week if their soybean fields have reached the V2 stage. Based on last year’s data, soybean plants prior to the V2 (Fig. 2a) stage generally lack the presence of cracks or fissures (Fig. 2b) at the base of the stem. Plants without fissures are not considered to be susceptible to soybean gall midge infestation. If growers have fields at VC or V1, we recommend waiting until V2 to make an application if they are in a high-risk area and have adult activity occurring.


 

Figure 1. Soybean gall midge alert network trap sites with a yellow dot indicating activity and the number of adults collected at that site.

 


 

Figure 2. Soybean plants (a) at V1 and V2 stage with close up of the stem (b) showing differences in the formation of fissures or cracks at the V2 stage.

 

In 2019, pyrethroid insecticides applied at different timings relative to adult emergence showed a significant yield response in Nebraska when applied up to 10 days after the first emergence was detected. It’s important to note that none of those treatments provided complete control of soybean gall midge. In addition, the study was conducted on a field that was planted to soybean the previous year. Since soybean gall midge is a field edge infesting pest, growers may only need to treat the first 60 to 120 feet of a field edge that is directly adjacent to a field that was injured the previous year.

Soybean Gall Midge: Should I Spray Checklist

• Soybean gall midge adults have emerged in my area

• My soybean field is at the V2 stage

• Soybean gall midge injury was noticeable in the adjacent field last year

For more details about gall midge, management strategies and the alert network, see the article “2020 Soybean Gall Midge Alert Network.”


Contact:
Justin McMechan
402-624-8041
justin.mcmechan@unl.edu