Managing winter weeds in bermudagrass pastures

Like most warm-season grasses in North Carolina, bermudagrass pastures go into a dormancy period once temperatures begin to drop in the fall. This period of dormancy is when the bermudagrass focuses its energy to the roots which allows it to survive through the colder months. During this time, winter weeds thrive under the cool conditions and if left unchecked, can compete with bermudagrass as it breaks dormancy in the spring and affect pasture quality.

Toxic Properties

Some winter weeds, such as buttercup, can be toxic to livestock if consumed. It has been reported that livestock that eat buttercup may develop: diarrhea, blisters in the mouth and on the skin. This usually occurs when there is no other forage growing in the pasture which highlights the importance of scouting your pastures and managing winter weeds in a timely manner.

Weed Identification

Before controlling winter weeds, it is important that you properly identify your problem weed(s). There are numerous winter weeds that can be found in pastures including: henbit, dandelion, Carolina false dandelion, geranium, chickweed, wild onion/garlic, wild radish, primrose, red sorrel, buttercup, and the list goes on and on. Most weeds are pretty easy to identify once they begin flowering. Unfortunately, once weeds begin to flower you are going to have a hard time controlling them so the trick is to identify them before flowering. If you need assistance with weed identification and control options please contact the Extension office.

Cultural Control

Some winter weeds such as red sorrel are an indicator of undermanaged pastures and thrive in acidic soils with low nutrient indices. These can be managed over time with a proper fertilization plan and adding the recommended amount of lime and nutrients to the soil.

Overseeding pastures with cool-season forages such as clover species, cereal rye, oats, or triticale, can suppress many winter weeds by competing for sunlight, nutrients and water. Using cool-season forages provides both weed control and feed for livestock to graze in the winter and spring.

Chemical Control

Sometimes even after the proper management practices are made, such as liming and fertilizing, weeds seem to persevere in the field. For these troublesome weeds, you may need to consider an herbicide treatment. If treated early, many of our winter broadleaf weeds can be managed with an application of dicamba or 2,4-D, while some weeds, such as wild onion/garlic, may require multiple applications. Undesirable grassy weeds like foxtail barley will not be controlled with a broadleaf herbicide. In this scenario, it may be best to apply glyphosate (Roundup, etc.) while the bermudagrass is dormant.

Regardless of the weeds that are present in your pasture, they must be treated early. This means making your application before flower development. As the days get longer, many winter weed species will begin reproduction or flowering. Weeds become much harder to manage during the flowering stage because at this point, plants have completed most of their vegetative growth. This usually occurs around March for most weeds so plan to make your application no later than February. Additionally, try to avoid making an application during a period of cold or wet weather.

Research has shown that when temperatures are below 60 degrees, absorption of 2,4-D is lower compared to the absorption of 2,4-D at higher temperatures. Herbicides are only effective when the weeds are actively growing so pick a mild day and make your application to achieve good control. Remember: no matter what herbicide product you choose, always abide by the product label and keep an eye out for grazing restrictions!