Chemical control of weeds is not always possible, Matt McGowin, a DuPont range and pasture specialist based in Flowood, Miss., says, depending on conditions. While some parts of his Southeast region experienced drought within the past few years, more recently excessive moisture has created weed challenges. Last year brought heavy rainfall to much of the region, and this winter has been colder and wetter than normal. McGowin expects a wet spring will limit access for tractors and application equipment in many pastures at the ideal times to treat weeds, particularly winter annuals that emerge early. Early indications suggest a late, wet spring could be a common trend around the country.
If Southern producers cannot get in to spray weeds until May or June, McGowin says, they can find mature winter annuals such as buttercup and henbit, along with summer perennial weeds such as horsenettle and dog fennel. The mix of mature annual and perennial weeds presents control challenges, and he says broad-spectrum herbicides probably need to be applied at higher application rates than would be needed earlier in the season.
When weather delays treatment of these weeds, a significant percentage of the season’s forage production could be lost by the time you treat, due to competition for sunlight, water and nutrients. Treatment will, however, benefit forage production the following year. If producers use a product with good residual action, McGowin says, they’ll typically see fewer winter annuals emerge the following season, particularly if they treat before the plants produce seed.
The price of weed control, including chemical applications, Deneke summarizes, represents a small investment relative to the potential loss of significant forage tonnage in a beef-production system.