0716GiantRagweedCropConcern.cfm Herbicide resistance found in giant ragweed
Home News Livestock Crops Markets Hay, Range & Pasture Home & Family Classifieds Resources This Week's Journal
Agro-Culture Liquid Fertilizer



Farm Survey


AgriMartin
Journal Getaways


Reader Comment:
by Wheat_Harvest movie

"Thanks so much for the article! These are the types of people we hope to"....Read the story...
Join other discussions.

Herbicide resistance found in giant ragweed

Advertisement

Missouri

When it comes to weed pests, glyphosate-resistant waterhemp tops the list, but resistant giant ragweed may be the challenger.

"Giant ragweed certainly has my attention," Kevin Bradley, University of Missouri Extension weed scientist, told pest management field day visitors at MU Bradford Farm. "We'll focus our research on giant ragweed, both resistant and not."

Bradley considers the resistant waterhemp a statewide problem. "We're not focusing on any more surveys of waterhemp," Bradley said. "I'm confident it is just about everywhere corn and soybeans are grown."

On the most recent survey, when waterhemp was tested from 144 locations across the state, 58 percent of the populations were resistant to glyphosate. A new survey tested giant ragweed from 27 farms, with 12 found glyphosate-resistant.

Bradley collects weed seeds in the fall from random fields, not just those suspected of having resistance. The seeds are grown in an MU greenhouse. At various stages weeds are sprayed with different concentrations of glyphosate or ALS herbicides. Those that thrive in spite of herbicide are labeled resistant.

"My concern is not just herbicide resistance, but multiple resistances," Bradley said. What started as resistance to glyphosate, the most widely used herbicide, has become resistance to other herbicides.

The newly resistant giant ragweed has been found to tolerate high levels of glyphosate and to have at least moderate resistance to ALS herbicides.

"It will take a combination of herbicides to control the resistant weeds," he said.

At another stop on the MU weed tour, Bradley said best control of weeds is obtained with a two-pass system. Herbicide is sprayed before planting to control overwintering weeds and emerging seedlings. Then the growing crop is sprayed with a post-planting application to control new weeds.

"The majority of the time this two-pass system works best," Bradley said. "There is a definite yield advantage."

However, new herbicide combinations with longer life show promise. "A one-pass system that includes a residual herbicide is becoming more popular with farmers," Bradley said.

At a third stop, Bradley showed off what he called "research that we can't say much about." The soybeans, mostly weed-free, are tolerant to 2,4-D herbicide, an older chemistry that was widely used for years.



Google
 
Web hpj.com

Copyright 1995-2014.  High Plains Publishers, Inc.  All rights reserved.  Any republishing of these pages, including electronic reproduction of the editorial archives or classified advertising, is strictly prohibited. If you have questions or comments you can reach us at
High Plains Journal 1500 E. Wyatt Earp Blvd., P.O. Box 760, Dodge City, KS 67801 or call 1-800-452-7171. Email: webmaster@hpj.com

 

Archives Search







Inside Futures

Editorial Archives

Browse Archives