This proposal addresses the priority area of Soybean Pest Management. It focuses on research into managing against yield and quality limiting effects of stem rots. Soybean stem diseases are widespread and damaging across Minnesota. They can kill plants or may be undetected and yet cause yield losses. A better understanding of when and where stem diseases occur and how to manage them more should result in yield benefits in many regions. This proposal is directed at brown stem rot (BSR) and pod and stem blight, two common stem diseases. The goals are to identify resistance to these diseases in breeding lines and varieties adapted to Minnesota, determine prospects for disease management with fungicides and crop rotation, and understand the distribution, frequency, and risks of soybean stem diseases. The occurrence and types of stem diseases (e.g., BSR, stem canker, pod and stem blight, charcoal rot) may to be changing in response to cropping and environmental factors, suggesting that soybean growers and their advisors better understand these risks to plan for appropriate management. This proposed research builds on a related set of projects conducted in the previous year and addresses short- and long-term goals to manage important soybean stem diseases.

1. Assess and improve strategies to manage brown stem rot of soybean.
2. Advance management of pod and stem blight of soybean
3. Understand the distribution and prevalence of important soybean stem and root diseases/pathogens in Minnesota.

o Identify resistance to both prevalent types of the BSR pathogen in an expanded selection of soybean breeding lines and varieties from the U of MN soybean-breeding program.
o Determine if promising new methods to evaluate soybean for resistance to BSR are more consistent and have higher throughput than current methods.
o Determine the effects of seed treatment fungicides and potential alternative hosts of the BSR pathogen on risk and management of BSR.
o Identify the levels of resistance to the pod and stem blight pathogens in soybean breeding lines from the U of MN soybean-breeding program and select commercial varieties.
o Develop and extend updated information on the management, distribution, and risks of key soybean stem and root diseases for Minnesota soybean growers.

This proposed project will address the need for improved understanding and management of key soybean stem diseases that reduce soybean yields across Minnesota. Enhanced understanding of where stem diseases occur and managing them more effectively should lead to increased soybean yields in many fields. Results will be transferred through newsletters, production meetings and field days, scientific meetings, and agricultural news outlets. The ultimate benefit to soybean growers will be increased yields and reduced risk of lost yields due to disease.