One of the biggest yield threats for Iowa corn continues to be corn rootworm. Northern and western corn rootworm are persistent pests in continuous cornfields and can potentially impact the profitability of every farm in Iowa.
Studies show that rootworm populations are increasing, and recent weather events like severe drought and severe storms have further exacerbated feeding injury.
Recognizing the damaging effects of corn rootworm in Iowa, a team of agronomists and entomologists with Iowa State University Extension and Outreach organized hands-on educational demonstrations across the state in 2022.
The sessions were held at seven of Iowa State’s research farms, with the goal of helping farmers improve their identification of the common corn rootworm species found in Iowa, increase producer confidence in recognizing and rating larval root injury, and help producers understand effective management options.
Each research farm planted a demonstration showing a range of management tactics, from the “do nothing” approach (no Bt traits or insecticide) to the “kitchen sink” approach (Bt + RNAi + soil applied insecticide). Participants were able to compare different management tactics, learn about the “float test,” observe a spectrum of root injury, and practice using the 0-3 node injury scoring system.
Attendees also got to interact directly with extension personnel to answer questions in small groups.
Some 55 participants responded to a post-event survey, with 82% reporting they had a “high confidence” in their ability to identify northern and western corn rootworm adults, following the sessions.
Participants also increased their ability to recognize and rate root injury from corn rootworm larvae, while also increasing their understanding of the complexity of effective corn rootworm management.
Most of the farmers who attended the demonstrations plan to use their new knowledge to make management changes for corn rootworm, and nearly 80% of farmers who responded to the survey expect to increase their profits by at least $5 per acre on their combined 6,118 acres.
The project was co-lead by Ashley Dean and Erin Hodgson, entomologists with ISU Extension and Outreach.
“The statewide corn rootworm demonstrations during the summer of 2022 provided farmers, crop consultants, and industry professionals the chance to observe management tactics, assess root injury, and increase knowledge of identification and sampling for corn rootworm,” said Dean. “The corn rootworm demonstrations improved the confidence of participants in diagnosing corn rootworm issues in the field and knowledge of corn rootworm management tactics, which prepares them to make sustainable and profitable management decisions in the future.”