Ohio State specialists to study weeds

Researchers from Ohio State University’s College of Food, Agricultural and Environmental Sciences are looking to collect samples of several weed varieties that are herbicide-resistant and could pose problems for growers in the region, said Mark Loux, an OSU Extension weed specialist.

Loux is collecting the samples as part of an effort to track herbicide-resistant weeds that are beginning to show up in Ohio fields that have caused problems for growers in other states. The goal is to try to prevent the weeds’ further spread in Ohio.

At the top of the wanted list is Palmer amaranth, which also is known as a “pigweed on steroids.” Palmer amaranth, a glyphosate-resistant weed that has wreaked havoc for Southern U.S. growers, has been found at several sites in Ohio.

“We are ideally looking for seeds from plants that survived a herbicide program that has typically provided effective control in the past, or repeated application of glyphosate or other herbicides,” he said.

Other weeds from crop fields the team is looking for include seeds from populations of johnsongrass, and pigweeds such as redroot pigweed, waterhemp and Powell amaranth.

A benefit of tracking these weeds is the data can be used to track where the problems are and try to stay ahead of problems that are developing, Loux said.

“We can also use the data to raise awareness of the next problems growers could be facing,” he said. “Palmer amaranth is a huge problem in the south and we want to let people know that it has been found here in Ohio.”

In addition to raising awareness, researchers can use the data to find out how to develop management and control recommendations for Ohio growers, Loux said.

Signs that a resistance problem may be developing include patches of surviving weeds in a field that is otherwise free of weeds or an atypical appearance of plants due to regrowth following treatment with herbicide, he said.

Weed samples will be accepted until Oct. 30 with a goal of emailing results to growers in February or March.

A sample submission form can be found at

When submitting samples, they should be collected when the seed is mature, but fresh. Samples should be stored in paper, not plastic, bags, and they should be stored in open paper bags in cool, dry conditions until mailed.

Samples should be carefully packaged and shipped early in the week to avoid weekend layovers during which the sample will deteriorate.

Participants should be sure to include sample documentation and background information.

Samples can be sent to Mark Loux, Horticulture and Crop Science, 2021 Coffey Road, Columbus, OH 43210.