By Scout Nelson
Early fall is one of the best times to manage perennial weeds in lawns and turf. During this season, weeds naturally move nutrients to their roots to prepare for winter.
Applying herbicides at this stage ensures that the chemicals reach deep into the roots, killing the plant completely instead of just removing surface growth.
Translocated herbicides from the synthetic auxin family—such as 2,4-D, dicamba, mecoprop-p, quinclorac, triclopyr, and clopyralid—are most effective in fall. Common lawn care products like Trimec® often include these ingredients.
These herbicides work best when temperatures remain above 60°F, although they can still be effective in cooler conditions. Light frosts do not reduce performance, but several hard freezes can limit effectiveness. Soil moisture also enhances herbicide action, so watering before treatment is beneficial.
Triclopyr is especially helpful for controlling difficult weeds such as wild violet, creeping bellflower, and ground ivy. When choosing products with triclopyr, make sure they are labeled for lawn use.
Since it can harm nearby trees or shrubs, apply only on calm days with winds below 10 mph. Avoid the ester form of triclopyr, as it is more volatile; instead, use the triethylamine salt version for safety.
For Canada thistle and other thistle species, clopyralid offers better results than standard lawn herbicides. Products like Lontrel®, Stinger®, and Transline® are commonly used for large-scale turf, parks, or pastures. However, Lontrel® should not be applied to residential lawns.
By applying the right herbicide during early fall, homeowners can successfully reduce perennial weed populations. With careful selection and timing, lawns stay healthy, green, and weed-free throughout the growing season.
Categories: South Dakota, General