The definition of a weed is a plant growing where it is not wanted. Weeds in a pasture can limit productivity, reduce forage growth, and cause livestock harm. Weeds and forage grasses are constantly competing for resource and can be costly for producers.
Characteristics that make up a good plant consists of a preferred perennial forage that is competitive and high in nutritional value. This desired plant should have rhizomes below grown and stolons above ground to tolerate grazing. The plant should also be able to adapt to a wide range of soil characteristics. Weeds can become a problem when they have multiple modes of reproduction. Weeds that produce a high number of seeds or spread by vegetative propagation can take over a pasture. Animals find some of these weeds unpalatable because of a thick stem, thorns, or odor. Forage grasses and weeds both have similarities to be competitive in a pasture. When introducing new plants species into our pastures from different regions we want to make sure they will not become a problematic weed. Vaseygrass and smutgrass both produce a lot of seeds and are not palatable at stages of maturity by livestock. These plants can also be a problem for hay producers. Tropical soda apple and blackberry both produce thorns making them less palatable and more competitive. Repetitive mowing can be a helpful weed control method to weaken some problematic weeds over time to the point where the weed does not recover. However, mowing can increase fossil fuels and increase cost for labor and gas. In contrast, herbicides are a cost effective control method. The disadvantages are herbicide can cause non-target plant injuries from drift and some herbicides can have grazing and hay restrictions. Using herbicide repetitively can cause weed resistance so it is important to rotate herbicides with different modes of action.
It is important for a producer to have an effective weed management program and practice good pasture management to help combat weeds.
Source: UF/IFAS Pest Alert