Minnesota Crop News

Bruce Potter, Extension IPM specialist Soybean gall midge larvae on soybean stem. It is later than typical, but we finally detected the emergence of overwintering generation adults in SW MN on June 23. Apparently, our emergence cages missed the beginning of the emergence by a few days. While we did not notice any obvious symptoms, soybean stem dissections revealed some small white larvae. By June 27, we were starting to see a few 3rd instar larvae. Soybean gall midge field day Take advantage of this opportunity to view a soybean gall midge infestation in Rock County near Luverne, MN. Date : Wednesday, July 13 Time : 1 - 3 pm Location:  Provided after registration This field day provides a hands-on opportunity for those interested in seeing and learning about soybean gall midge, a soybean pest identified in Minnesota in 2018. You will learn how to recognize soybean gall midge larvae and the symptoms of a soybean gall midge infestation. The current knowledge of soybean gall midge b...

This weekend's record-breaking heat stalled the risk of initial infections of most all of the foliar fungal pathogens and Fusarium Head Blight.  As temperatures have dropped from their record highs and a couple of cold fronts have resulted in widespread thunderstorms across the northern half of Minnesota, the risk of initial infections of tan spot and leaf rust is increasing again. A quick check of your pant legs at 10:00 in the morning or 9:00 at night will be very telling - if you end up with wet pant legs you probably are encountering long enough leaf wetness periods for either disease to start. If you find tan spot while scouting for weeds and testing how waterproof your workboots really are, it is a good idea to add half a labeled rate of a fungicide to your weed control program. If you can not find any tan spot, do not add a fungicide and you save yourself some money.  Research from NDSU has shown again and again that you will not see a return on your fungicide appl...

Bruce Potter, Extension IPM Specialist True armyworm. Photo: Bruce Potter Several additional reports of true armyworm infestations have come in from a wide area in southern and into west central Minnesota. There are likely fields in other geographies that saw armyworm moth immigrations, as well. Migration patterns Migrating armyworm moths have been moving into Minnesota since early May. Based on the descriptions of larval size and moth captures, the infestations being reported are likely related to moths arriving with a series of storms about three weeks ago ( true-armyworm blacklight captures ). These were not extremely large flights compared to those during other outbreak years but were evidently large enough to create some problems. Since then, subsequent southerly winds continue to bring armyworm moths into Minnesota as far north as Roseau County. This means that armyworm infestations might continue to show up for a while. Any moths from these flights would have sought out and lai...

By: Melissa Wilson, Extension manure management specialist, and Josh Gamble, USDA-ARS research scientist Key Points: Growing perennials, like alfalfa, can have water quality benefits while still producing a crop for cattle feed Using manure during the alfalfa rotation is often avoided, leaving a smaller land-base for manure to be applied New liquid manure application equipment plus the use of traffic-tolerant alfalfa varieties may reduce some of the negative aspects of manure application on a living crop like alfalfa What we did: We have two main goals in this ongoing study: Evaluate a traffic tolerant variety of alfalfa for manure application Determine if the use of dairy manure, fertilizer, or a combination of both throughout the 3-year alfalfa growth cycle could be used to maximize growth and quality We established two different varieties of Roundup Ready alfalfa in the spring of 2021 at the University of Minnesota’s Rosemount Research and Outreach Center: Pioneer 54VR10-RR (hig...

 Anthony Hanson, Extension Educator - Integrated Pest Management Especially in central Minnesota, multiple calls have been coming in about what to do about alfalfa weevil in mid-June. After first cutting and seeing visible feeding damage in the regrowth, it may be tempting to immediately consider an insecticide, but threshold and mowing recommendations should still be followed this late in the season. That is because multiple factors, such as the weevil’s life cycle, mowing schedules, and hot temperatures can work in our favor and could make a return on investment on insecticide unlikely in multiple situations at this time. A May MN Crop News article went into detail on alfalfa weevil scouting and thresholds . This follow-up will address three main questions you should ask yourself towards the end of alfalfa weevil season: Do current mowing plans alter treatment decisions? Will the damaging stage (larvae) be present in the near-future? Are you in a window where insecticide applicat...

Bruce Potter, Extension IPM specialist Scout any corn planted into a rye cover crop for armyworm now! The first true armyworm infestation in corn has been reported in south central Minnesota. These larvae survived the heat wave.  Winter rye is a magnet for armyworm, but dense, lodged grasses, including cereals, may also be attacked.  Mowing roadside or ditch hay may actually drive larvae into susceptible grass crops.  There have also been scattered reports of poor performance of pyrethroid insecticides on large armyworm so check control after treatment. Remember that chlorpyrifos is no longer labeled for use. A diamide insecticide or diamide mix are options for control. For more information, see https://extension.umn.edu/corn-pest-management/armyworm .

Angie Peltier, UMN Extension crops educator and Phyllis Bongard, UMN Extension educational content development and communications specialist Early soybean aphid infestation. Photo: Bob Koch On June 15, UMN Extension IPM specialist, Bruce Potter, Extension entomologist, Dr. Bob Koch and UMN/NDSU Extension agronomist Dr. Tom Peters, joined Extension educators Dave Nicolai and Dr. Anthony Hanson for a discussion about strategies for managing pests and weeds in 2022. This was the sixth episode of the 2022 Strategic Farming: Field Notes program this year. To listen to a recording of this episode subscribe to Strategic Farming: Field Notes on your favorite podcasting platform or visit this website: https://strategicfarming.transistor.fm/# . Managing insect pests in 2022 How will late planting affect soybean aphid and bean leaf beetle populations?  Pests like soybean aphid and bean leaf beetle tend to prefer to colonize the earliest planted fields. Bean leaf beetle which overwinters in le...

MN-Rothsay hard red spring wheat variety released by U of MN, 2022. The University of Minnesota has released a new hard red spring wheat variety called ‘MN-Rothsay.’ MN-Rothsay features a good combination of yield, protein, and disease resistance and exceptional straw strength. “MN-Rothsay has straw strength comparable to Linkert but has about 10% higher grain yield,” says Jim Anderson , University of Minnesota wheat breeder in the Department of Agronomy and Plant Genetics. “The exceptional straw strength of Linkert was largely responsible for its 5-year reign from 2016-2020 as the most popular variety in the state. We expect MN-Rothsay’s higher grain yields, which are comparable or higher than other popular varieties, and improved disease resistance compared to Linkert will be attractive to growers and increase wheat productivity.” Prior to being formally named, MN-Rothsay was tested as MN15005-4. The line stood out in both state and regional trials including the Uniform Regional Nurs...

Joe Ikley, Extension weed specialist, NDSU, Debalin Sarangi, Extension weed scientist, Tom Peters, Extension sugarbeet weed specialist, and Dave Nicolai, Extension educator - crops Rapidly growing giant ragweed in corn. Photo: Lisa Behnken Spring planting in many areas of Minnesota and North Dakota was delayed due to unseasonably cool and wet conditions which have resulted in delayed crop emergence and crop growth. However, crop and weed growth has greatly accelerated with recent above average air temperatures. As a result, postemergence herbicides have been applied in less than desirable hot temperatures and windy conditions thus limiting the desired application window for area row crops. Some areas have received rainfall this month and while that’s a brief respite from the above average temperatures, the weather forecasts still predict some hot (90 – 100 degree) and dry weather as we continue the postemergence spray season. There are several details one needs to consider when making...

By Robert Koch (Extension Entomologist) & Bruce Potter (Extension IPM Specialist) We are beginning to see soybean aphids colonizing some soybean fields in southern Minnesota. These aphids are in very low numbers and only on a small fraction of the plants, so they are currently not a threat to yields. However, late June is a good time to begin scouting for soybean aphids. Initially, prioritize scouting “indicator” fields, which are the fields where you typically see soybean aphids colonizing first. Often, these are early planted fields, small fields with wooded borders, and fields in areas with abundant buckthorn. Finding aphids on plants early in the colonization process when aphids are few and far between can be challenging, but the presence of lady beetles and ants on soybean plants often a sign that aphids are there. Indicator fields can provide the first clues on the number of aphids that were able to move from buckthorn to soybean and if (or how fast) populations are increas...

In this episode of the Nutrient Management Podcast, we discuss iron deficiency chlorosis (IDC) and soybean nutrient management. What are our guests working on for research on IDC? Is there anything new out there for farmers to help manage IDC? With the late planting and dry conditions following last year's harvest, are any impacts on IDC anticipated this year? View the podcast transcript Guests: Dan Kaiser, Extension nutrient management specialist (St. Paul) Seth Naeve, Extension soybean agronomist (St. Paul) Maykon Junior de Silva, U of M graduate research assistant (St. Paul) Additional Resources: Managing iron deficiency chlorosis in soybean U of M soybean fertilizer guidelines Video: Maykon Junior de Silva presentation on recent IDC research --- For the latest nutrient management information, subscribe to the Nutrient Management Podcast wherever you listen and never miss an episode! And don't forget to subscribe to the Minnesota Crop News daily or weekly email newsletter,...