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6 Ways to Whip Weeds in 2018

Looking to sharpen your 2018 weed-management strategy? Here are six recommendations for the coming year.

1. Use preemergence residual soybean herbicides.

“If you are looking for ways to cut costs, I highly recommend taking a look at where you can get the most return on investment,” says Dawn Refsell, Valent field market development manager. “Preemergence residual herbicides have the highest and greatest return on investment. So that ought to be the last area you should look at cutting when evaluating weed-management strategy.”

It’s tempting to think you need to see a weed before you kill it with a postemergence herbicide. A preemergence residual herbicide, though, can knock it out before that stage.

“Killing a weed is always easier before it comes up,” says Joel Leusink, a Winfield United agronomist.

2. Don’t make a weed mad.

Sure, it may be tempting to cut costs by slashing recommended herbicide rates. What often results, though, are wounded weeds that survive the initial post-emergence application then bounce back and set seed for the next year, says Leusink.

For waterhemp, its 250,000 or so seeds that may germinate is akin to 250,000 upraised middle fingers in your field that you have to deal with in future years.

3. Read the herbicide label – really read it.

With all the adjuvants and herbicides with multiple modes of action going into spray tanks these days, there’s a possibility you could slip up and add them in the wrong order.

“With the addition of multiple products, mixing order is more important than ever,” says Leusink. Testing mixing order into a Mason jar can save you headaches later. After all, it’s a lot easier to clean a gelled mess out of a Mason jar than it is a sprayer tank.

4. Make postemergence herbicide applications in a timely manner.

Yes, those tiny Palmer amaranth seedlings that just emerged in your field really can grow 2 to 3 inches per day. “You can go from being on label to off label in a matter of hours,” says Refsell. “The taller the weeds, the harder they are to control.”

5. Remove rogue stray waterhemp or Palmer amaranth plants.

This can prevent them from going to seed. Then, haul them away from the field, advises Refsell.

In late summer, weed seeds can potentially germinate if the pulled plant is left in the field. “Physically removing them from the field is the best way to eliminate weed seeds,” says Refsell.

6. Be wary of other weeds.

Granted, waterhemp and Palmer amaranth grab weed headlines these days. Still, there are some old standbys that still infest fields, such as velvetleaf.

“It just never goes away,” she says. “It doesn’t have the prolific seed production of waterhemp or Palmer, but it just never goes away.”

University of Missouri weed scientists note that preemergence herbicides are the most effective at managing velvetleaf, which allows a crop to gain a competitive advantage.

Most two- or three-way prepackaged combination products that contain atrazine (Corvus, Callisto, Hornet, Python) and where velvetleaf has not resisted it yet provide good preemergence control in corn.

In soybeans, most of the Authority products (Canopy, Envive, Fierce, Fierce XLT, Firstrate, Gangster, Pursuit, Python, Sencor, Sharpen, Trivence, and Valor XLT) are all effective preemergence herbicides for velvetleaf.

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