Never Too Late To Start

March 6, 2015

Four Weed-Management Tactics You Can Still Implement This Year


If a management plan for combatting herbicide resistance isn’t part of your operation yet, experts say it’s never too late to start. While there are many steps that farmers can take, weed scientists from around the country say starting with even a few practices can go a long way. Here are four practices farmers can implement yet this year:

1. Start weed-free

Before the planter rolls, fields should be weed-free. Whether by cultivation or herbicide burn-down, starting with a clean environment is important.

Daniel Stephenson, Louisiana State University AgCenter weed science professor says, “the number one thing is to ensure they have destroyed every plant present, either by tillage or herbicide, so when the seed is planted there is nothing there to inhibit its growth. Most crop plants are sensitive to early competition.”

2. Think Pre

For the past two decades, many farmers have relied on the practice of controlling weeds solely by using post-emergent herbicides like glyphosate. Experts strongly encourage farmers to hit the weeds before they start to grow.

“Incorporate effective pre-emergent herbicides into your practice, using a totally different mode of action,” says Rich Zollinger, professor and weed-control specialist at North Dakota State University. “Weeds haven’t seen a lot of that chemistry, so it can be very effective in controlling resistant weeds.”

Residual control is also valuable to give soybeans and other crops time to reach canopy and shade out weeds.

3. Diversify Post

Scientists and experts across the country have long preached the importance of using herbicides with diverse modes of action.

“My comment for the past 15 years has been to do practices that keep the weed and insect pressure off balance,” says Minnesota crop consultant Van Larson. “That means to not do the same thing with any one of the control measures available.”

Mark Loux, weed scientist at Ohio State University, agrees: “The biggest thing farmers can do to prevent resistance is to use a rotation of chemistries and sites of action. Rotate the basic approach so that you don’t treat the same weeds with the same chemistry every year.”

4. Scout

Walking fields after applying post-emergent herbicides will reveal whether any resistant weeds have survived. If you find escapees, those plants contain the gene that makes them resistant to the herbicide you used. Show them no mercy.

“Be vigilant to see if there are weeds that didn’t die,” Zollinger adds. “If weeds did escape, do what you have to do to kill them and that resistant gene. If you don’t, you’ll have bigger issues.”

If farmers have not begun planning against resistance, a visit with an agronomist or crop consultant could be a good place to start.

“Ask what system of weed control has been successful in the area,” Larson says.” You don’t have to reinvent the wheel for success. Remember that weed control has always been an ongoing and changing process.”