Crop rotation for corn rootworm control
March 22, 2021
With corn rootworm pressure increasing in the state, the Iowa Soybean Association is offering a trial opportunity meant to dig into the economics of crop rotation as well as corn rootworm control.
ISA Field Services Program Manager Teresa Middleton says being mindful of our management and use of tools with corn rootworm will be important as the pests have demonstrated resistance to four different Bt toxin traits. Middleton says there is academic support for rotating crops as an effective tool with one study finding even a 1% increase in rotated fields decreases fields severely affected by rootworm by 3.7%. Additional benefits of rotation unrelated to corn rootworm includes an increased yield, a reduction in fertilizer needs and helping to control other corn diseases and non-rootworm pests.
Examining data, she reports in 2019 11% of all cornfields were above the economic threshold of two beetles per day per trap and in 2020 increased to 22%. In continuous cornfields the increase went from 18% of fields to 33% in 2020. For first year corn or corn after soybeans the increase was only from 3% to 3.9%.
“We are looking for participants to help us dig into the economics of rotation a little bit more,” Middleton says. “We ‘re looking for fields that have been in corn for at least two years that can be planted to half corn and half soy.
“We would also need your yield data from the fields in 2020 and 2021 and what we’ll do is we will come out and quantify corn rootworm damage and pay out a $750 hassle fee on receipt for the data. The main goal of this trial is to compare the difference on return on investment for corn on corn in a corn soy rotation in a field that has been receiving corn rootworm pressure.”
Those interested in participating can contact ISA Senior Field Services Program Manager Scott Nelson.
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