6 Weed management considerations for now and 2017

Here are some weed-control tips picked up at farm shows and field days this summer to help you form future weed-management strategies.

Apply preemergence residual soybean herbicides. “With people looking for ways to cut costs, I would highly emphasize they look at where they 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 should be the last area a grower should look at cutting when evaluating weed-management strategy.”

A preemergence residual herbicide can halt a weed before you even see it. “Killing a weed is always easier before it comes up,” says Joel Leusink, a WinField agronomist.

Don’t make a weed mad. Sure, it may be tempting to cut costs by slashing recommended postemergence herbicide rates. What often results, though, are wounded weeds that survive the initial postemergence application and bounce back and set seed for the next year, says Leusink.

In the case of waterhemp, its 250,000 or so seeds that could potentially germinate are akin to 250,000 upraised middle fingers in your field that you have to deal with in future years.

Read the herbicide label. Really read the herbicide label. That’s because 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 in an old Mason jar can save you headaches later. After all, it’s a lot easier to clean a jelled mess out of a Mason jar than it is out of a sprayer tank.

Make timely postemergence herbicide applications. 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 weeds are, the harder they are to control.”

Rogue stray waterhemp or Palmer amaranth plants. This can prevent them from going to seed. Then, haul them away from the field, advises Refsell. By now, seeds have already developed and 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 seed,” says Refsell.

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

University of Missouri weed scientists note that preemergence herbicides are most effective in managing velvetleaf and allowing a crop to gain a competitive advantage. Most two- or three-way prepackaged combination products that contain atrazine (where velvetleaf has not resisted it yet), Corvus, Callisto, Hornet, and Python 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 velvetleaf herbicides.