By Scout Nelson
Managing weeds is crucial for optimal crop growth, and understanding when and how to apply herbicides can make a big difference. As crops like corn and soybeans grow, weeds such as giant ragweed, waterhemp, and lambsquarters are also progressing, with some already reaching 4-6 inches in height. If you haven’t started post-emergence herbicide applications yet, it’s time to act.
Herbicides, particularly post-emergence ones, require actively growing plants to work effectively. Timely rainfall can activate pre-emergence herbicides, but delays in rain may result in weeds emerging unaffected, requiring quicker applications. When applying herbicides, it’s important to consider the growth stage of both your crops and weeds, as well as product-specific guidelines to avoid crop damage.
For crops like corn, there are restrictions on herbicide applications depending on the crop’s growth stage. For example, applying atrazine after the corn reaches 12 inches is illegal, and herbicide labels should always be carefully checked to ensure compliance with usage rates and application timing.
Water quality also plays a significant role in herbicide efficacy. Many Minnesota producers use well water, which is typically hard and contains high salt concentrations. Testing water quality and using water conditioners like ammonium sulfate can greatly improve herbicide effectiveness.
Herbicide-tolerant soybean varieties, such as the E3 trait package, offer the flexibility to use multiple herbicide groups, but proper adjuvants, such as methylated seed oil, are necessary to meet application standards.
Lastly, managing weeds is not just a short-term task. For crops like sugarbeets, aggressive, multi-year weed control strategies reduce the weed seed bank and provide better results over time. A solid foundation of pre-emergence herbicides in preceding crops, along with non-chemical tactics, helps ensure long-term weed control success.
Photo Credit: gettyimages-fertnig
Categories: Minnesota, Crops, Corn, Soybeans