The agronomist pulls their pickup off the road and enters their fourth field of the day. As the sun has climbed in the eastern sky, so has the temperature. The agronomist, however needs to press on since corn borer damage is showing up in their county. They systematically work their way down and across the first rows of corn. In short order, they spot shot holes in the corn and start counting procedures as they transect the field.

Fig. 1 Agronomist scouting a corn field. (Image credit: D. Lee)

Fig. 2 Corn plant with shot holes. (Image credit: D. Lee)

Twenty minutes later they are back at the truck and making calculations. The European corn borer damage observed clearly indicates numbers beyond the economic threshold so they head over to their customer’s place to deliver a treatment recommendation. The farmer won’t like the news, but time is money and treating now will protect a crop that looks great except for the cornborers.

“You saw what in that field?” was the farmer customer’s initial response. “That can’t be right."

It always takes some time to get to know a new customer so the agronomist is guarded in their next comments. They start with mentioning the fields scouted yesterday that had corn borer. Other scouts they talked with yesterday were seeing them. It seems to be a good year for corn borer. “But you shouldn’t be finding them in that field…it’s a Bt hybrid! Are you sure you were scouting the right field? Is there a way to check the plants and make sure they are really Bt plants? Could the corn borer be resistant to Bt? Maybe you just checked the refuge acres and not the whole field? Are you sure you know what corn borer damage looks like?”

The agronomist takes a breath before proceeding. They know the answer to the last two questions but pull out the map so the customer can verify they are talking about the same field. Confirming that, the agronomist asks if the hybrid number planted was indeed the number in his notes. “Yes,” emphasizes the customer, “ The number I gave you is a new hybrid I’m trying and the salesman said it was a Bt hybrid. Did they give me the wrong stuff?” In a minute the Agronomist pulls up hybrid corn information on the laptop. As they read across the trait information for their customer’s number, they find the answer.

The agronomist offers this reply. “There is a test the seed company can do right in the field to verify that those plants have the ‘Bt’ trait you paid for, but observing European corn borer feeding on this hybrid is not unexpected.” The agronomist proceeds to explain to the customer how a plant can be a Bt hybrid but not be designed to kill European corn borer (ECB).

Copyright 2003

Development of this lesson was supported in part by Cooperative State Research, Education, & Extension Service, U.S. Dept of Agriculture under Agreement Number 98-EATP-1-0403 administered by Cornell University and the American Distance Education Consortium (ADEC).  Any opinions, findings, conclusions or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.