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Nutrient Removal and Chemical Resistance: How Weeds Are Damaging Your Field


Nutrient Removal and Chemical Resistance: How Weeds Are Damaging Your Field


Using Different Methods
to Attack Resistant Weeds

Herbicide-resistant weeds are changing farm management plans across the country, including the plans that Hoxie, Kansas, farmer Mitchell Baalman has for his fields.

"We are starting to see herbicide resistance in our area, like with Palmer amaranth," shares Baalman. "We've gone back to using preemerge products to kill the weeds when they are young or before they germinate. And we are using a variety of chemicals to keep resistance to a minimum."

The climate where Baalman farms proves to be a challenge, too. In an arid area with approximately 15 inches of rain a year, some of the chemicals applied early in the season and that require moisture to continue working aren't controlling late-season weeds. Some farmers in his area are using other methods.

"Some neighboring farmers are trying to use cover crops to control resistant weeds, by creating competition for moisture and nutrients," explains Baalman. "But some years, there isn't enough moisture to grow a promising cover crop. In my area, farmers are all talking to each other to see what is working and what isn't. Weed resistance is a problem we all face, and so we need to work together to address it effectively."

Weeds are more than unsightly plants in a field. They're thieves. They rob soil moisture and nutrients from the competing crop and decrease harvest efficiencies. Weeds also compete with the crop for sunlight. Because they are plants competing to survive in a limited space, weeds are actively removing nutrients from the soil to grow taller, stronger and healthier each day. By removing nutrients for their own growth and development processes, weeds are leaving crops with lower amounts of key nutrients necessary to maximize yields. Research has shown that up to 60 percent of yield is dependent on soil fertility, and weeds that rob nutrients from crops limit yield potential.

What complicates matters worse is the issue of herbicide-resistant weeds. As with any natural evolution process, weeds are becoming more resistant to popular herbicides used to control them. For instance, glyphosate-resistant weeds are growing in number, affecting nearly half of farmers surveyed in 2012. Farmers planting glyphosate-tolerant crops are changing management practices to better control resistant weeds. These practices can range from changing crop rotations to applying preemerge herbicides or herbicides of a different chemical class that are more effective on resistant weeds.

Proactively managing nutrient levels and eliminating weeds are the best ways to ensure crops have the nutrition they need for the entire growing season.

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