Syngenta Seeds is contacting growers and seed dealers who purchased five hybrids grown in a narrow band of the northern Corn Belt. While not all plantins of these hybrids have exhibited symptoms, some have shown stress following a glyphosate treatment, the company reports. The five hybrids share a single parental line and range from 100 to 103 days of maturity. Here are the numbers:

Growers who have planted these hybrids are urged to contact Syngenta at (800) 258-0498 before making any further crop management decisions, including application of glyphosate.

"These hybrids represent less than 1% of our corn seed portfolio and less than one-tenth of one percent of total U.S. corn acres," says Chuck Lee, corn product line head, Syngenta Seeds. "We are working with growers who have purchased these hybrids to assess options to avoid or mitigate any potential damage from these stress symptoms."

The seed passed all quality control tests and the glyphosate trait was expressed, Lee says. He adds that the company is attributing what it sees to environmental conditions affecting one specific parent line common to these hybrids.

The map below shows the general area where these hybrids have been planted.