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by Dr. Don Ball

The dictionary defines ecology as "the area of science dealing with the inter-relationship of organisms and their environment." As compared to other types of agricultural production, pasture ecology is particularly interesting and complex because it involves animals, plants, soil and the many climatic and environmental factors that affect them.

A livestock producer has many problems and opportunities to deal with on a daily basis, so it may be difficult to find the time to think about the whole picture. Yet, an overall awareness and understanding of the influences that shape pastures is necessary to be a good manager. This article, which deals with pest influences, is the second of a series that deal with pasture ecology

Insects- Thousands of species of insects can damage the forage species used in the South. In most cases, this damage is relatively minor and does not justify treatment, but there are many exceptions. In general, high value crops such as alfalfa, or seedling forage crops that do not yet have a good root system and that cannot tolerate extensive damage are those on which the use of insecticides can be most easily justified. Advances in variety development have resulted in resistance to some insect pests.

Diseases- Most diseases of forage crops are highly specific and attack only a particular forage species. In addition, diseases are usually most likely to occur, and are most damaging, when plants are already weakened by other stress factors. The possibility of disease problems increases the desirability of using mixtures of species when feasible. For example, a producer in the Deep South who is establishing a winter annual pasture reduces risk slightly by planting mixtures of wheat and rye as compared to either species alone. Resistant varieties are the best means of control of forage diseases, but cultural practices also play a role in reducing the incidence of some diseases.

Weeds- Weeds are a particularly common pasture production problem. In addition to lowering pasture yield, quality, and/or stand life, some weeds are toxic to animals. All the influences that affect forage plants in a pasture also affect weeds. When a livestock producer manages pastures in such a manner as to favor desirable forage species, a situation is simultaneously being created that has an adverse effect on most weed species. This is simple, but extremely important pasture management concept.

Nematodes- Nematodes are microscopic organisms that live in the soil and parasitize the roots of various types of plants, including forage crops. The primary damage nematodes cause is to upset the efficiency of moisture uptake by plants. Consequently, plants that have shallow root systems and/or that are being grown in locations in which moisture availability is marginal are most susceptible to nematode damage.

Cool season perennial species are severely penalized by nematodes when grown on sandy soils. Other crops such as bahiagrass and bermudagrass are more tolerant of nematodes, primarily due to a deeper and more extensive root system. Warm season forage species also apparently tend to be less preferred by nematodes. A few forage crops are resistant to certain nematode species.


As with other types of crop production, growing pastures involves dealing with pests. Knowing the types of pests most likely to be a problem and prevention of a situation favorable for pest problems to develop are the best strategies. Selection of pest-resistant species and varieties, frequent monitoring to detect possible problems, and providing a situation conducive to growth of vigorous, competitive forage crops are keys to minimizing pest damage to pastures.

Don Ball is an Extension Forage Crop Agronomist with Auburn University.

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Date Last Updated January, 2006