Early Season Pasture Weed Control and Management

William Hogan  |  3/15/2012 6:09:09 PM

An application of early spring fertilizer will stimulate Bermuda grass to early production.

Many plants that grow in our native pastures also have the potential to poison cattle including sicklepod.

Most ornamental plants are toxic to some extent to farm animals, including iris.

The winter of 2011-2012 has been one of the warmest in memory. It has also been one of the wettest in several years. This has made for much better cool season forage production than we normally experience. The fall weather allowed for more ryegrass to be planted. Growing conditions for winter forage was generally good. We are experiencing near record warm temperatures this spring. Most of our warm season pastures and hay fields began growth in early March, an entire month earlier than we usually experience. These conditions have placed livestock producers in a favorable position regarding animal nutrition and condition. With the high market price of cattle this is even more advantageous. To keep this favorable pattern moving into the summer months, livestock producers should now control pasture weeds and manage fertilizer applications efficiently.

Growing conditions for weeds have also been excellent. Research has shown that weeds rob you of production and reduce the quality of your pastures. The longer weeds compete with forage grasses, the greater the loss to the cattle producer. An application of early spring fertilizer will stimulate Bermuda or Bahia grass to early production. A spring application of a recommended broadleaf herbicide is more effective in weed control than a summer application. Young weeds are more susceptible to control and require less herbicide per acre to be effective. By removing the competition early, pastures have a longer time to be productive.

It is more economically critical than ever to make sure that the forage grass is the beneficiary of the fertilizer rather than weeds. Controlling pasture weeds will increase the efficiency of a fertilizer application. A study conducted at the Texas A&M Research Station in Overton, Texas, compared a spring application of 2,4-D plus fertilizer to a plot that received fertilizer but no herbicide. When harvested, both yielded similar tonnages of total plant matter. However, the plot without herbicide produced more tons of weeds than grass.

Many plants that grow in our native pastures also have the potential to poison cattle. Most of the time these plants will be in a pasture for years and will never be eaten by an animal. If the cow doesn’t eat it, it can’t hurt the cow. However, certain conditions such as drought, overgrazing or starvation will cause cattle to consume plants not in their normal diet. A hungry cow will eat lots of things that it normally wouldn’t.

Curiosity will cause certain individual cows to sample toxic plants. Calves are born knowing that they have to eat, but not what to eat. They learn this by observing their mother and their herd mates. A group of young heifers or steers, confined alone, will often experiment with eating plants not in their normal diet.

How sick the cow becomes could depend on which plant it eats, how much it eats, which part of the plant is consumed, growing conditions of the plant, age of the animal and many other factors. To be safe, try to learn which plants are potentially toxic and how to recognize them.

Plants that have shown toxicity to cattle include: pokeberry, jimson weed, bracken fern, cocklebur, horsenettle, nightshade and perilla mint. Two common toxic weeds are sicklepod and hemp sesbania (coffee weed). All parts of the sicklepod plant are toxic whether the plant is green or dry. Hemp sesbania (coffee weed) has most of the toxin in its seeds. Cattle tend to eat hemp sesbania most often in late summer, fall and winter when forage grass is scarce. The coffee senna plant is very toxic, but fortunately is less common in our area. It resembles sicklepod, but its seed pods are straight and flattened. Perilla mint is a small plant that tends to grow in pastures, along roadways and around old home sites. It often shows a distinctive purple coloration on the underside of the leaf. Perilla mint is often consumed by “curious” young animals.

We have many excellent pasture herbicides available to us. Identify the weeds that you have present. Determine which herbicides are labeled in their management. If applicable, select the least costly per acre herbicide that will effectively control the weed. As in the management of any pest, proper timing of application is just as important as which pesticide to use. Always read the label and follow all instructions and restrictions when using any pesticide

Most ornamental plants are toxic to some extent to farm animals. Some common toxic ornamental plants include: lantana, yew, azaleas, caladium, oleander and iris. These are seldom a problem unless they escape cultivation and grow in a pasture. Lantana and oleander are extremely toxic to cattle in small amounts. These plants grow well in our climate and are prone to escape. The most common cause of poisoning by ornamental plants is by accident. The homeowner will prune back a yard plant or remove some of its limbs. If the limbs or the foliage is thrown over the fence into the pasture, a curious cow will often try to see what it tastes like. It only takes a mouthful of oleander or lantana leaves to cause real problems for a cow. To be safe, treat all ornamental plants as if they were toxic to livestock.

Rate This Article:

Have a question or comment about the information on this page?

Innovate . Educate . Improve Lives

The LSU AgCenter and the LSU College of Agriculture

Top