SW MN IPM Stuff 2022 Issue 4

Volume 25 Issue 4 | April 29, 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.  

Crop Progress

It’s been another week of some rain, mostly cold temperatures, and plenty of wind in SW Minnesota. Fieldwork has just barely started here. The April 25ths USDA Crop Progress & Conditions report continued to show a few days suitable for fieldwork. The only crop planting reported was 2% of oats. Statewide planting progress was the lowest since 2013, which, coincidentally, also followed a dry year.

Most days, soils have remained cold with 2” soil minimum temperatures in the 30s. There were still 10 inches of frost here on the 25th. Fortunately, most local soils have not been overly wet and should be in good shape once we get a period of rain-free, warmer weather. The near-term forecast is not helpful, but it is still relatively early, too early to be mudding things in. Compacted soils have the unique ability to magnify the effect of both excess rainfall and drought.

Small grains (winter cereals)

Lamberton winters can be tough, especially when there is a lack of snow cover. Winter barleys did not survive in the study planted here last fall. Survival of triticale was variable.

Most wheat varieties at the SWROC survived several brief periods of bitter cold with little snow cover and are greening up. This will be one of the first areas I will look for cereal aphids and symptoms of the barley yellow dwarf virus they transmit.

Cereal rye almost always looks good, and this year is no exception. The hybrid rye looks good also.  

Dense stands of grasses, including rye, are attractive to egg-laying armyworms that arrive this spring. Remember this in your corn scouting efforts this year. Rye is also a good place to detect migrating cereal aphids and aster leafhoppers.

Spring wheat and oats

April has been too damp to get the spring cereals studies planted at the SWROC. They were ready to go but got rained out today. Some SW MN farmers with a little less spring rain or a little lighter soil have had better luck.


Growth is slow but the younger stands I’ve been in look good. Areas, where water stood, may be different. I have not yet detected any insect pest pressure, but I was reminded that a sweep net is an ineffective tool when it’s windy.


It sounds like there has been some corn planted in a few areas this week but not much. The seed for 2022 SW MN IPM experiments has been patiently waiting for the go-ahead to spring into action. About once a day, I’ve visiting the seed storage building and telling the seed bags to calm down and be patient. It seems to be working – for now. Any corn that has been planted should be OK but as always, there may be some hybrids or seed lots that struggle with cold, wet soil conditions.


Nothing happening yet.

Weeds are a chronic problem and will be again in 2022.

Sure, the timing, rate, and level of emergence of a weed species are determined by weather, but you can count on weeds every year. Being so predictable is a management benefit compared to plant disease and insects. For each field, have an idea of the weed species and densities you need to deal with and decide on an appropriate herbicide Plan A and a Plan B.  

I’ve seen a few giant ragweed seedlings, but the cold soils have temporarily slowed the emergence of most annual weeds. Soil moisture should help PRE herbicide performance this spring. The timing of weed emergence can affect the effectiveness of early season weed management tools such as spring tillage and pre-emerge herbicides.

Even if planting delays continue, help yourself by including an appropriate pre-emerge herbicide. 

Expect to see more late weed flushes and more barnyard grass if it’s a wet season. Cool weather that slows crop canopy, will favor weeds.

Volunteer corn is going to be a real issue in many fields with drought stress or lodging from wind or poor stalk quality during 2021. Letting volunteer corn persist can reduce soybean yield and the effectiveness of crop rotation against corn rootworm and some diseases.

The 2021 drought created the conditions for soybean harvest losses. Many, maybe most, volunteer soybeans germinated last fall which can be helpful in disease, SCN, and even soybean aphid management. Select corn post-emerge herbicides that will control significant populations of 2022 volunteer soybeans.

Although you may have planted a variety or hybrid with a particular herbicide-tolerant trait, it does not prevent you from using another labeled herbicide option. The situation may have gotten better but herbicide availability may limit options Develop a plan but be flexible. Don’t be outwitted by the vegetables.

Disclaimer: I used to be a fair botanist, but I am not a weed scientist.  

Fungal kingdom news

For the electrical engineers - Magic mushrooms?

I spent a few years with an office in a university plant pathology department. The department and I both survived, more or less, but I am not a plant pathologist.  Nevertheless, I used to get embarrassed when making the rare bad call on a crop disease but not anymore. I had not realized what we were up against. Recent research in the United Kingdom describes talking mushrooms!  The paper is highly technical, but it poses, perhaps, a moral dilemma.

Adamatzky, Adam. 2022.Language of fungi derived from their electrical spiking activity. R. Soc. open sci.9211926211926. http://doi.org/10.1098/rsos.211926

Plant vs Fungus (Sclerotinia white mold and plant defenses)

In a running battle much, much older than Godzilla vs. Rodan and Mothra, plants and their fungal pathogen attacks have traded genetic blows as they evolve. As plant genetic defenses against fungal pathogens are selected, it’s reasonable to assume that, in turn, fungi have been responding with their own genetic counteroffensive. A recent email from the USDA-ARS news service highlighted a recent discovery on one of the ways that white mold gets around plant defenses (https://content.govdelivery.com/accounts/USDAARS/bulletins/314a8e4).

For professional and amateur plant pathologists that want to learn even more, you can wade through the Nature Communications article:

Wei Wei, Liangsheng Xu, Hao Peng, Wenjun Zhu, Kiwamu Tanaka, Jiasen Cheng, Karen A. Sanguinet, George Vandemark, Weidong Chen. A fungal extracellular effector inactivates plant polygalacturonase-inhibiting protein. Nature Communications, 2022; 13 (1) DOI: 10.1038/s41467-022-29788-2

Happy trails,