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Plan Ahead to Protect Corn and Soybeans from Weeds

March 30, 2018
This agronomic image shows waterhemp in a soybean field.


It’s that time of year again when spring begins and yield-robbing weeds start to emerge. Recent reports show Palmer amaranth appeared as early as late February, so understanding how to combat these invasive pests is vital.

If you want to maximize yields this year, we recommend getting ahead of difficult-to-control weeds before the season kicks off. The first step is knowing which weeds you can expect to emerge and when.

This chart breaks down weed emergence sequences into 5 groups, from earliest emergence to latest:

Group 0 weeds include winter annuals that complete emergence in the fall or early spring: Marestail (horseweed)

Group 1 begins to emerge several weeks prior to planting: Giant ragweed, lambsquarters, common sunflower

Group 2 beings to emerge around planting: Woolly cupgrass, common ragweed, velvetleaf, giant foxtail

Group 3 begins to emerge at the end of planting: Yellow foxtail, black nightshade, common cocklebur

Group 4 emerges after crop emergence: Large crabgrass, fall panicum, waterhemp, morningglory

Syngenta has a full portfolio to combat these weed pressures in both corn and soybeans.

In corn, we recommend using Acuron® or Acuron Flexi, with multiple sites of action (SOAs). Both products provide application flexibility, with the ability to spray from 28 days preplant to 12” corn for Acuron, and 28 days preplant up to 30” corn for Acuron Flexi. A 2-pass system can also include a post-emergence application of Halex® GT corn herbicide for an additional site of action.

In soybeans, we recommend making a pre-emergence application of Boundary® 6.5 EC, BroadAxe® XC or Prefix®, each containing 2 SOAs. Boundary 6.5 EC and BroadAxe XC can be followed up with a post-emergence application of Flexstar® GT 3.5 for 2 additional SOAs.

If you need help implementing an effective herbicide program, use our Resistance Fighter® program to learn more about how to get a customized herbicide program that’s right for the spectrum of weeds on your operation.

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