SW MN IPM Stuff 2021 Issue 13

8/20/2021 |  Volume 24 Issue 13

This newsletter and the advice herein are free. You usually get what you pay for.

Greetings,

Soybean gall midge has been found in 139 counties in five states with 25 new counties this year (Figure 1).  Overall, 2021 crop injury from soybean gall midge in Minnesota has been less than previous years. However, as the second larval generation developed during late July and August 2021, infestations became easier to locate and the soybean gall midge has now been detected in 12 more Minnesota counties.

These new county infestations were not at high soybean gall midge population densities. For most of these MN detects, there were not symptoms of dead or wilted plants to provide clues (Figure 2). We needed to look for symptoms at the base of stems (Figure 3) beneath normal-appearing canopies. In some cases, brittle stems resulting from soybean gall midge injury made finding the larvae easier but even then, only a few infested plants were found in these fields. This week, a sharp-eyed farmer in Traverse County found soybean gall midge by inspecting a single plant with a broken stem in one of his fields.

We have also observed soybean gall midge in Minnesota on the alternate host sweet clover. It has not yet been found on dry beans in commercial fields or potted greenhouse grown dry bean cultivars plants placed in infested fields. 

We are still capturing emerging soybean gall midge adults, so soybean death and stem breakage is likely to continue over the next several weeks. If you observe soybean gall midge, particularly in a Minnesota county where it has not yet been confirmed, please contact [email protected] or [email protected]. Infestations can be confirmed with a photo and field location.

Updated distribution maps, gall midge adult emergence and other information is available at: https://soybeangallmidge.org/.

Checkoff dollars through the North Central Soybean Research Program and Minnesota Soybean Research and Promotion Council have helped support these survey activities.

 

Map showing counties in South Dakota, North Dakota, Nebraska, Minnesota, Iowa and Missouri with soybean gall midge infestations dicovered in 2018, 2019, 2020, and 2021
Figure 1. Distribution of the soybean gall midge as of August 18, 2021. Source: https://soybeangallmidge.org/.
edge of a soybean field with wilting plants infested with soybean gall midge
Figure 2. Wilting soybean gall midge infested plants at ae field edge adjacent to 2020 soybean. The amount of injury in this Rice Co. field, although minor, is much more visible than most new county detections.

 

 

 

 

 

 

 

soybean stem with several orange soybean gall midge larvae on it
Figure 3. Stem injury and soybean gall midge larvae beneath the outer layer of the stem. Look for the dark border between the healthy green tissue and calloused injured tissue below. Pull back the outer layer to confirm larval presence.
 

 

 

 

 

 

 

 

 

 


 

 

 


EPA revokes crop tolerances for chloryprifos

The potential loss of chlorpyrifos (e.g., Lorsban) as a crop protection chemical has loomed for some time. The recent decision means that chlorpyrifos will no longer be allowed for use on crops after the current growing season. This crop news article discussed the EPA decision and alternatives for MN crop production.

Corn disease

Although it is a dry, it does not mean pathogens are taking a year off. See this article for information on tar spot of corn.

Harvesting drought-stressed corn

Because of uneven maturity influenced by drought stress, there will likely be some grain moisture issues at harvest.

Some have decided to not take some droughty fields to grain and there has already been some silage chopped in SW MN. There are several good recent articles on harvesting drought-stressed corn for silage, etc. See Harvesting drought stressed corn for silage and Harvesting drought-stressed corn as baleage.

Events

Missed the corn rootworm field day at the SWROC at Lamberton last week, here is another opportunity at Rosemount.

Happy trails,

Bruce