The weed science program at the University of Illinois is offering free screenings for herbicide resistance in waterhemp to Illinois farmers during the 2013 growing season. Aaron Hager, associate professor of weed sciences at U of I, says with continued financial support from the Illinois Soybean Association, over 1,000 plant samples have been screened through the collaborative effort between the U of I and the ISA.

“This valuable service helps farmers and researchers track and understand the evolution of herbicide resistance in waterhemp across the state,” he says.

While there is no fee for the program, Hager says the timing of when the results of each screening would be available could not be guaranteed.

“Also, because of the way in which we conduct our resistance tests, a test result of ‘sensitive’ to glyphosate does not rule out the possibility that the plant actually is resistant by a mechanism different than that of which we are testing,” Hager says. “We will not make the exact location of any samples or names associated with samples available to anyone without permission.”

Details for Illinois farmers collecting plant samples are as follows:

  • Following application of glyphosate, select five waterhemp survivors in the field.
  • Remove the top inch or two (containing young, newly emerged, healthy leaves) from each plant and place inside in a sealed, sandwich-sized plastic bag. Use a separate bag for each plant.
  • Place the bags in an envelope and send by overnight delivery to Chance Riggins, 320 ERML, 1201 W. Gregory Dr., Urbana, IL 61801. Do not submit samples to the U of I Plant Clinic. Do not mail samples on Friday or Saturday. 
  • The submission form should be printed and completed for each field sampled.

Ideally samples should be sent the same day they are collected, Hager said. If necessary, however, they can be stored for a day or two in a refrigerator (but do not freeze) until shipped, he added.

For more information, contact Pat Tranel at 217-333-1531 or tranel@illinois.edu.