The Good Ole Days?
Back in the days before glyphosate-tolerant crops became so pervasive, weed resistance fears centered on ALS herbicides, which were used to control waterhemp. Currently, nearly all waterhemp populations are assumed resistant to ALS herbicides because of the intense use of these herbicides.
One key difference between then and now is glyphosate-tolerant crops emerged to aid in weed control and alleviate pressure from ALS-herbicides, allowing another chemistry to be used. Today there are no new modes of action being developed to relieve the pressure from glyphosate. In spite of research efforts by chemical companies, nothing has been found. And, a new herbicide would take at least 10 years to reach the market should something be discovered today.
For this reason, many waterhemp populations, as well as other weed species, can be found to have resistances to multiple modes of action. Weeds remember they're resistant. Regardless of the reduced use of ALS herbicides in favor of glyphosate, those populations that were ALS-resistant have not disappeared. Multiple resistance makes weed control a tougher battle by leaving few options available for control.
All the more reason that growers need to develop an integrated weed management program that included rotating crops and herbicide modes of action, including a pre-emergence residual herbicide in both corn and soybeans, and integrating non-chemical control methods when available.
In soybeans, a herbicide like Prefix® will provide the residual control to help protect your crops until a post-emergence application can be made. Similarly, in corn, Lumax® or Lexar® offer great early-season weed management.
There might be times when breaking out the disk and tilling up the ground may be one of the only options remaining. Before getting to this point, a proactive approach and trying to delay the onset of resistance can be more profitable.
Describe your weed control program--how many modes of action do you typically integrate in your corn and/or soybean program? Are you facing multiple resistant weeds? If so, what is the situation? And, what are you doing to combat them?
Important: Always read and follow label instructions before buying or using these products. Lexar and Lumax are Restricted Use Pesticides. Lexar®, Lumax® and Prefix® are trademarks of a Syngenta Group Company.