Field Crops IPM Podcast: Soybean and corn diseases in late summer and what to plan for next year

Welcome to the 2nd IPM Podcast for Field Crops of 2020. Subscribe to the podcast and never miss an episode on iTunes, Google Podcasts, and Spotify.

This Podcast is sponsored by the UMN Extension Integrated Pest Management (IPM) Program. In this week’s podcast, we feature Dr. Dean Malvick, University of Minnesota Professor of Plant Pathology. Dr. Malvick discussed what diseases he is keeping an eye out for in Minnesota soybean and corn:

Soybean diseases

White mold symptoms are beginning to occur, though the next few weeks will tell how severe it is region-wide. Dr. Malvick explained how we are past the window where treatments would be effective for white mold, but growers should consider varieties for next year that have partial white mold resistance, though no variety is entirely immune.

Sudden death syndrome (SDS) of soybean is caused by a fungus that infects roots early in the season, and symptoms are generally not visible until later in the season. It has been confirmed in most counties in the southern half of Minnesota. Varietal selection and possibly seed treatments can be tools to consider for next year.

Interveinal chlorosis, a primary symptom of SDS on soybean

Frogeye leaf spot has been increasing in the state the last few years when wet and warm conditions occur. Resistance to strobilurin fungicides has been confirmed in the state, and will not be effective when used alone. Reports of this disease have been confirmed as north of Stearns county and Dr. Malvick would be interested to see photographs or samples of this disease to monitor where it is the state. 

Corn diseases

Tar spot, first found in Minnesota in fall 2019, was recently confirmed in southeastern Minnesota again this year shortly before this recording. Dry conditions may slow development, but the disease needs to continue to be monitored to see what extent it will have in the state. Dr. Malvick mentioned Corn ipmPIPE as one resource to see where previous reports of tar spot and other corn diseases have occurred.

Bacterial diseases such as bacterial leaf streak and Goss’s wilt are also a concern. Some varieties have resistance to Goss's wilt, possibly reducing prevalence. However, bacterial leaf streak is a fairly new bacterial disease of concern found in the southern half of the state. It causes lesions on corn leaves, and can be especially damaging to sweet corn.

Bacterial leaf streak lesions. Photo: Dr. Vince Frtiz, UMN Extension

If you have questions about diseases in your field, especially if you believe you have tar spot, frogeye leaf spot, or other corn or soybean diseases Dr. Malvick mentioned he would like to hear about, contact him at dmalvick@umn.edu. For plant disease identification services, visit the UMN Plant Disease Clinic website for information on submitting samples.

This podcast was hosted by Dr. Anthony Hanson, Extension Post-Doctoral Associate. The purpose of the IPM podcast is to alert Growers, Ag Professionals and Educators about emerging pest concerns on Minnesota field crops. We also review recent pest trends and research updates.

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For IPM Program updates, visit the UMN Extension IPM website.