On June 24, Matt Pfarr, University of Minnesota Extension Educator – Crops, and Dr. Bob Koch, University of Minnesota Extension Soybean Entomologist, joined moderator Dave Nicolai, University of Minnesota Extension Educator – Crops, to discuss crop development, disease outlook, nutrient management, and soybean insect scouting during the University of Minnesota Extension Strategic Farming: Field Notes webinar.
The Strategic Farming: Field Notes webinar series provides timely, researchbased information on current crop production issues throughout the growing season. The series is held Wednesday mornings from 8 to 8:30 a.m. and is supported by the farm families of the Minnesota Soybean Research & Promotion Council and the Minnesota Corn Research & Promotion Council.
The webinar highlighted key management considerations as corn enters rapid vegetative growth, including following herbicide label restrictions, meeting the crop’s increasing nitrogen demand, and scouting for diseases such as tar spot, which has been reported in neighboring states but has not yet become widespread in Minnesota.
“Corn is entering the period of peak nutrient uptake, so management decisions made now can have a significant impact on crop performance later in the season,” said Pfarr.
Pfarr also encouraged growers to wait one to two weeks before assessing hail-damaged corn and soybean fields, allowing time to accurately evaluate crop recovery. In soybeans, he stressed the importance of timely post-emergence herbicide applications to control small waterhemp and discussed management considerations for iron deficiency chlorosis (IDC), including selecting tolerant soybean varieties.
Koch reported that soybean aphids are present in many Minnesota fields but remain well below the economic threshold for treatment. He encouraged growers to begin regular scouting through at least the R5 growth stage and reminded producers that treatment decisions should be based on economic thresholds to protect beneficial insects.
“The economic threshold of 250 aphids per plant allows time for treatment before yield loss occurs while providing beneficial insects an opportunity to naturally suppress aphid populations,” said Koch.
Koch also discussed the continued presence of pyrethroid-resistant soybean aphids across Minnesota and highlighted newer insecticides with alternative modes of action that continue to provide effective control. Importantly, he noted that his research has shown that applications of pyrethroid-containing insecticides can result in more soybean aphids than if no insecticides were applied. He concluded with an update on soybean gall midge, encouraging growers to scout field edges for early signs of infestation as the pest continues expanding across southern Minnesota. The webinar recording is available on the Strategic Farming podcast and website for those unable to attend the live session.
