By Scout Nelson
With warm weather and moist soil, weeds are growing fast and competing with crops for sunlight, water, and nutrients. Even if a preemergence herbicide was used, scouting fields early is important.
Postemergence herbicides work best when weeds are small—around 3 to 4 inches tall. At this size, they are easier to kill and less likely to survive treatment. Some weeds like water hemp can grow an inch per day, so acting quickly is essential.
There are two main types of herbicides: systemic and contact. Systemic herbicides move throughout the plant and are better for deep-rooted or perennial weeds. Contact herbicides only affect parts they touch and work best on small, annual weeds.
Environmental conditions matter. For example, contact herbicides work best on warm, sunny, humid days. Avoid spraying when it’s windy, below 50°F, or during temperature inversions to reduce spray drift and improve results. Also, check the herbicide's fast rain period and avoid rain soon after spraying.
Using a mix of herbicides with different modes of action can help control more types of weeds and prevent resistance. Adding a residual herbicide to a postemergence spray helps stop late-season weeds and keeps them from producing seeds.
Always follow label directions, especially crop stage limits, to avoid crop damage. Spraying too late can hurt plant growth and reduce yields.
Take-home tips:
- Spray weeds early, before they reach 4 inches.
- Choose the right herbicide for your weed type.
- Pay attention to the weather when spraying.
- Mix herbicides and rotate them to stop resistance.
- Add residuals to control late weeds
Photo Credit:gettyimages-zoomtravels
Categories: Minnesota, Crops, Weather