February 22, 2016
Every soybean field deserves its own weed-control program. Customized programs that switch up and combine herbicide modes of action will help control yield-robbing weeds and help keep herbicide-resistant weed populations under control.
Invest Now or Pay Later
Low commodity prices make it tempting to cut corners on weed control. But Louisiana State University weed scientist Daniel Stephenson points to glyphosate-resistant pigweed and ryegrass as prime examples of why a wait-and-see approach to weed control is a bad idea. “Invest now or pay later,” advises Stephenson. “If you back off weed control and get bit, you’re going to get bit hard.”
Applying glyphosate or glufosinate alone will not provide adequate control of resistant or hard-to-control weeds, including Palmer amaranth, morningglory or yellow nutsedge. Using more than one mode of action and layering residual herbicides is an important component of effective weed-control programs, says Louisiana crop consultant Ashley Peters.
Start Clean, Stay Clean
“We may start with a preplant application of glyphosate plus 2,4-D plus DuPont™ Afforia®, Canopy® EX or LeadOff® herbicide,” says Peters. “Then we may follow with DuPont™ Canopy® DF plus metolachlor at planting, and an application of DuPont™ Classic® plus glyphosate (on Roundup Ready soybeans) or Liberty (on LibertyLink soybeans) plus metolachlor and/or fomesafen early postemergence to get soybeans to canopy. It’s a ‘start clean, stay clean’ program that works well.”
When selecting a DuPont preplant/preemergence program for soybeans, pay special attention to rotational crop requirements associated with chlorimuron ethyl, especially for rice and on high-pH soils. This is also important with postemergence herbicides containing fomesafen, which help control Palmer amaranth.
Soybean Weed-Control Programs
If weather and workload allow, it’s best to stay ahead of weeds with a preplant foundational residual herbicide as the first step in battling resistant weeds and achieving cleaner fields. Timely planting is key to maximizing soybean yield, which means growers should think carefully about how herbicide choices will affect preplant intervals, says DuPont Pioneer agronomy research manager Dan Poston. Preemergence applications of DuPont™ Envive® or Trivence® herbicide provide residual control, allowing postemergence applications to be made closer to soybean canopy to shrink the number of in-crop herbicide treatments needed.
With any preemergence weed-control program for soybeans, consider these points:
Start clean. Tank mix with an effective contact herbicide such as Gramoxone.
Use rainfall for activation or start a postemergence program earlier than normal (following label guidelines).
Apply a postemergence herbicide containing fomesafen/metolachlor or fomesafen about 21 days after planting, plus glyphosate for glyphosate-tolerant soybeans or glufosinate for LibertyLink soybeans.
A proven tank-mix partner for glyphosate or glufosinate (Liberty), Classic® herbicide boosts postemergence soybean weed control by improving control of broadleaf weeds, including yellow nutsedge, morningglory and hemp sesbania.
Watch videos showing herbicide trials at the DuPont Southern Virtual Field Tour. In the media gallery, click the pre-emergence and postemergence tabs to see side-by-side demonstrations.
Products listed above may not be available in every state. Contact your local DuPont representative for more information. Gramoxone (Syngenta); Liberty and LibertyLink (Bayer); Roundup Ready (Monsanto). Unless indicated, trademarks with ®, ™, sm are trademarks of DuPont or affiliates. © 2016 DuPont.
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