Sept. 11, 2006

Weed scientist asks Missourians to round up resistant seeds

COLUMBIA, Mo. - University of Missouri weed scientist Kevin Bradley is recruiting landowners, crop consultants, herbicide applicators and local cooperative employees to help determine the extent of glyphosate resistance in waterhemp.

Earlier this year, Bradley’s herbicide tests in a northwestern Missouri soybean field confirmed that tall waterhemp is the sixth glyphosate-resistant weed in the U.S. and ninth in the world. Glyphosate is the active ingredient in herbicides such as Roundup and Glyfos.

Bradley is asking people who believe they may have glyphosate-resistant waterhemp to submit seed samples.

Samples should be collected in a "W" pattern at least 50 feet from the edge of the field. The samples should be female seed heads only. Bradley suggests collecting 20-30 seed heads per field.

Collectors must fill out a questionnaire detailing the field’s location and crop and herbicide application history. Bradley would like a minimum of three to five years of information.

"The history is the most important thing," said Bradley. "It gives a clue as to what is going on in the field."

Fields that have been planted with the same crop for several consecutive years and have a history of repeated glyphosate herbicide applications are more likely to contain resistant varieties of the weed, he said.

Bradley plans to have research results in the spring from the samples collected this fall.

For a copy of the questionnaire or more information on submitting samples, contact Bradley at 573-882-4039.

Digital download available at: http://AgEbb.missouri.edu/news. Voice assistance at 573-882-4827.