Source: NCSU COOPERATIVE EXTENSION, 11/16/21


Bt corn has been genetically modified to make insecticidal proteins that protect plants from caterpillars and some root feeding beetles. In our region, growers pay an average of around $35 more for a bag of Bt corn compared to non-Bt corn. However, corn earworm, the most common caterpillar pest of NC corn, does not decrease yield when corn is planted within the recommended planting window. This is illustrated by the graph below, comparing yields of Bt and non-Bt hybrids with similar genetic potential in 2021- similar to 2020 and 2019, there was no yield difference. In other words, by planting Bt corn, growers are paying more for a seed with a technology that does not generally increase yield in NC. Other sporadic insect pests that may attack corn in our region are European corn borer and fall armyworm. For these pests, Bt corn may offer a yield advantage, especially if corn is planted later than the recommended planting window. Bt corn has been really successful to manage European corn borer and there is strong evidence that Bt corn has reduced the prevalence of this pest. Furthermore, in areas of the NC mountains where corn growers struggle with western corn rootworm, Bt corn has proven to be a valuable tool.

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