What Is Your Strategy to Beat Tough Weeds?

Husker Home Place

As the number of herbicide resistant weeds grows, we need to plan our weed control attack carefully.

Published on: March 26, 2013

I attended a weed resistance workshop in Norfolk last week, moderated by University of Nebraska Extension integrated weed management specialist, Stevan Knezevic. During the course of the meeting, UNL researchers painted the true picture of weed resistance issues that are going to plague farmers down the road, and they discussed ways to mitigate the speed with which these problems will occur, as well as strategies for beating up on the toughest of the resistant weeds.

Everyone in the room wanted to hear that some new technology had been discovered, and would be marketed immediately, to beat down glyphosate-resistant weeds like waterhemp and giant ragweed that are becoming more and more prominent. But, researchers don’t have a silver bullet or magic wand to make resistance issues disappear. The approach that will win the war on weeds will take a lot of muscle between the ears, as farmers develop their own strategies, within their own crop rotations, using tools that work specifically for them.

TOUGH CUSTOMERS: These weeds demonstrated at the study plots at David City last summer, are survivors and it will take careful consideration to control them.
TOUGH CUSTOMERS: These weeds demonstrated at the study plots at David City last summer, are survivors and it will take careful consideration to control them.

A case in point came when Knezevic discussed a specific giant ragweed “superplant” at the weed resistance study plots in David City that refused almost all treatments last summer. It was so tough that when Knezevic’s research team tried using propane burners and flaming on this weed numerous times throughout last summer, it still survived. Knezevic noted that he and his team have spent a good share of the past several years developing groundbreaking research on flaming weeds, establishing doses of flaming, and tolerance levels of specific weeds and crops to flaming treatments. This research is extremely useful to organic farmers who cannot use herbicides to control weeds. Knezevic probably knows flaming as well as anyone in the country. Still, this giant ragweed stood tall.

Only after multiple treatments with a good, old-fashioned disk, did the ragweed give way. This finding, while only a snapshot of the resistance issue, gives no-till operators some reason for concern.

No-till farmers in the room acknowledged that they simply did not want to till their soil at all, because of very real erosion issues on highly-erodible land. That puts them in a quandary. To add insult to injury for no-till farmers, cover crops, which have become a base component in the most successful no-till operations, will not thrive when farmers are forced to rotate herbicide chemistries beyond glyphosate to stay ahead of resistant weeds and protect glyphosate systems for the future. Talk about a double-whammy.

We have spent a lot of time covering no-till farming and the benefits of these systems for the soil, and especially in how they perform under recent drought conditions. So, you will have to read more in our May issue as we discuss in detail the findings related at the weed resistance meetings, and how these issues might be addressed by producers under varied cultural practices, including no-till. It won’t be easy, there is no doubt. It will take research, thought and creativity by farmers. Hopefully the information we provide will help farmers apply the findings to their own operations.

Here is this week’s multiple choice discussion question for you. What is your weed control strategy to overcome resistance issues? Let us know what you think will work best for you and why.

1) Use glyphosate repeatedly until it doesn’t work anymore. I’ll worry about it then.

2) Rotate crops and rotate herbicide chemistries and modes of action each year to slow resistant weeds on my farm.

3) Implement additional cultural practices like cover crops, occasional tillage on tough weeds, conservation tillage or flaming.

4) Dig the old cultivator out of the trees and learn to overcome “iron blight” again. Hand weeding on escapes.

5) Rotate cereal crops like wheat, rye and oats into the system to throw weed cycles off.

6) Learn to live with more weeds.

7) A combination of all of the above.

Be sure to follow Husker Home Place on Twitter. And watch Nebraska Farmer online and read our upcoming April print issue of Nebraska Farmer for news, information and tips on meeting the challenges of drought. Your best online resource for drought information is the Farm Progress drought site at Dateline Drought. And watch this blog this Friday for my new “Field Editor’s Report” featuring a Nebraska pork producer family growing worth from waste and generating electricity from their hogs. Pass it on!