SW MN IPM Stuff 2022 Issue 10

Volume 25 Issue 10 | July 1, 2022

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

Crop Weather

Rainfall, air and soil temperatures, degree-days, soil moistures, and other current and historical weather data for the University of Minnesota Southwest Research and Outreach Center (SWROC), a little spot about two miles west of Lamberton, MN, can be found at http://swroc.cfans.umn.edu/weather.  

Hot, dry, conditions and many days with windy weather persist in SW MN. Corn on some of the lighter or compacted ground is rolled during the day. Many fields with heavier soils still have good moisture further down, but some moderate rains would still be appreciated by many.  At the SWROC, there is no moisture in the top six inches and six to twelve inches are half of the long-term average moisture content. There is some hope for rain in the forecast.


I received a picture of a large yellow underwing/ winter cutworm (Noctua pronuba) larva. The larvae, found in new seeding alfalfa, were not causing significant damage yet. While the adults are not uncommon in light traps, damage to crops and turf has not been common in Minnesota. 

Potato leafhoppers have made it into SW MN. We have not picked up any nymphs at the SWROC yet. There are still some alfalfa weevil larvae present. Watch populations of alfalfa plant bug during this cutting. Red-legged grasshopper nymphs have hatched and are now active in some alfalfa. Red-legged and differential are the last southern MN crop pest species to hatch.

Small Grains

The heading and flowering of spring seeded cereals are nearing completion.

There has been an increase in true armyworm moth captures in blacklight traps this past week. The trap at the Southern Research and Outreach Center at Waseca caught 107 armyworm moths from June 25 to 29. These may be the progeny of the migrants that arrived earlier this spring. Be on the lookout for larvae starting in 2-3 weeks. These may move to other areas, including further north. On the bright side, a Redwood County grower reported good true armyworm control in rye with lambda-cyhalothrin, a pyrethroid.


After the 4th weekend take some time to look at fields with a high probability of early soybean aphid infestation (early planted, smaller fields with wooded and buckthorn borders, moderately dry soils with lower potassium levels) favor early-season soybean aphids. Aphids are rapidly increasing in one such area I often check at the SWROC, and low numbers can be found in many area fields as winged aphids move from initial infestation sites.

Larger bean canopies and reproductive stage soybeans will provide aphids an opportunity for rapid population increases even with hot, windy weather.

Soybean cyst nematode (SCN) are present in many fields now. Don’t assume yellow beans are due to IDC, mobile nutrients, or herbicide.

Soybean gall midge

As the summer progresses, look for wilting and lodged soybeans on field edges. Some of the plants in the left photo have early symptoms of soybean gall midge injury near the soil line. Both white and orange third-instar orange larvae right.

You may be interested in seeing this relatively new soybean pest and its injury symptoms in a field situation. We will hold a soybean gall midge field day near Luverne in Rock County, MN on Wednesday, July 13. Details and registration information can be found at: Soybean gall midge field day

Early season symptoms of soybean gall midge at the base of soybean stems.
Early season symptoms of soybean gall midge at the base of soybean stems.
Soybean gall midge larvae beneath the outer layer of a soybean stem.
Soybean gall midge larvae beneath the outer layer of a soybean stem.


Corn rootworm

We are starting to see a few early instar rootworm larvae in SW MN research sites. Currently, root injury is minimal, but it is still too early to evaluate root injury. Numbers here are currently low and indicate populations have declined but more likely, it is still early in egg-hatch.

Dry weather will favor the survival of young larvae and amplify the effect of root injury.

Enjoy the 4th Holiday and…

Happy trails,