With several factors resulting in greater-than-usual corn rootworm damage in many parts of the U.S. Midwest in 2020, corn growers have been encouraged to anticipate CRW pressure again in 2021 and take steps to protect their crops.
A major part of the 2021 message: Don’t skimp on use of soil insecticides, which several field trials suggest can make a difference in corn yields.
Seventeen AMVAC-sponsored university trials in 2017-2018, for example, set out to demonstrate the yield response AZTEC HC Corn Soil Insecticide produces in both conventional and traited corn. The trials featured AZTEC HC on rootworm trait hybrids (both single and dual mode of action traits) and hybrids without CRW traits.
The finding: AZTEC HC provided greater percent consistency of root protection across trials for each hybrid platform tested – with increased yields for every Refuge, single-, and dual-trait corn rootworm hybrid. Among traited hybrids, AcreMax Xtreme, for instance, yielded an average of 212.7 Bu/A when treated with AZTEC HC vs. 210.2 Bu/A untreated. As might be expected, the yield difference in hybrids without CRW traits (Refuge) was even greater: 197.2 Bu/A when treated with AZTEC HC vs. 177.8 Bu/A untreated.
Similar Results in 2020 Minnesota Trials
A 2020 trial conducted by University of Minnesota (UM) Extension and funded by AMVAC came to a similar conclusion. Setting out to evaluate the potential benefit of layering insecticides on corn hybrids without and with Bt rootworm traits, the trial found that application of AZTEC HC led to numerically higher yield across all trait platforms vs. untreated.
Average yield of SmartStax RIB, for example, was 195.7 Bu/A treated with AZTEC HC vs. 192.9 bu/A untreated (see Table 1). And again, yield difference trended higher with the non-CRW-trait Refuge hybrid: 180.0 Bu/A treated with AZTEC HC vs. 156.0 untreated.
A related trial by the same UM researchers, funded by AMVAC and Valent, looked to evaluate the efficacy of in-furrow liquid and seed applied insecticides against corn rootworm as compared to a granular in-furrow insecticide and a no insecticide control. A single hybrid, Lake Country LC 0488 VT2PRIB, was used.
Trial results showed that AZTEC HC and INDEX Liquid At-Plant Insecticide – both AMVAC products – had numerically higher yield than all other trialed insecticides. AZTEC HC led all products trialed with an average grain yield of 174.9 Bu/A.
The researchers noted that, related to corn rootworm efficacy, AZTEC HC was the only insecticide treatment that did not have a node injury score of more than 1 (one node pruned to within 1.5 inches of the plant).
“We’re pleased the results of these trials support not only the use of corn soil insecticides to control corn rootworm beyond traits, especially heading in a tough year for CRW pressure as is anticipated for 2021, but that they also highlight the market-leading position of AMVAC insecticides,” said Nathaniel Quinn, AMVAC Marketing Manager for Corn, Soybeans, and Sugar Beets. “AMVAC has solutions for CRW protection in both insecticide products and equipment choices.”