Biological control of weeds by natural enemies. Herbicides have been ineffective in controlling weeds in the field and their toxic and phytotoxic properties preclude their use for control of specific weeds. The use of biological control agents has increased in importance as a mechanism of control for weeds. The biological control of weeds has been reported for more than 100 different groups of microorganisms. Specific control has been achieved with bacteria, fungi, virus, protozoa and other multicellular parasites. In each case, the mechanism of control has depended upon the method of entry of the agent into the plant and thus the entry of the agent and its mode of attack can be considered important factors in the successful control of specific weeds. Recent studies have established that a large number of these agents may be released into the soil under conditions which are likely to occur under field conditions. There are, however, other mechanisms involved in control such as competition for resources, effects of allelopathy, and alteration of plant biochemical reactions. Mechanisms of control may vary greatly depending upon the weed or weed complex. A further important requirement for biological control agents to be used in practical situations is that the plants to be controlled should be readily infected. Otherwise, the agents become ineffective and in some cases they may even have a phytotoxic effect upon host plants. The effectiveness of biological control of weeds depends upon several factors such as: the nature of the interaction between the organism and the plant; weed physiological stage and size of the population; and the type of host-pathogen relationship. In general, it can be concluded that host responses to pathogens can be reduced and these effects can range from no effect, to altered growth and development, stunting of growth, plant death or elimination of the weeds. Control of soil-borne diseases by antagonistic microorganisms in the rhizosphere has been a long-standing quest, but the use of antagonistic microorganisms for disease control has several major drawbacks including, for example, that the control is only temporary and transitory, that only a small part of the root system may be treated with the control organism, and that the treatment may alter soil chemistry or other soil characteristics, thereby altering plant growth and soil erosion. These drawbacks have limited the use of biocontrol agents for many years. The present invention provides a method of controlling soil-borne diseases in plants using a single isolate which, when applied to a plant, controls the disease throughout the plant without harming the plant and which does not harm the ecosystem. The present invention may be used in one or more stages of the life of the plant and will greatly reduce the possibility of a plant being infected by several different pathogens at one time. In addition, none of the plant's resources will be exploited by the disease control agent, thereby preventing adverse effects on growth, development and productivity. This method of control allows the control agent to be applied to the soil before or after the plant is put into the ground and the control agent may be applied before or after the plant emerges. This method of control also allows the use of very small amounts of the agent, and a single application is often effective. One object of the present invention is to provide an improved method for controlling plant diseases, particularly fungal diseases, throughout the plant. Another object of the present invention is to provide a method for controlling soil-borne diseases which does not affect or harm other plants in the area, and which does not affect other soil organisms. Another object of the present invention is to provide a method for controlling soil-borne diseases which provides long-term protection against soil-borne diseases. Yet another object of the present invention is to provide a method for controlling plant diseases that is efficient and requires very little or no additional cost over conventional methods of disease control. Still another object of the present invention is to provide a method of controlling plant diseases which is environmentally friendly. Still yet another object of the present invention is to provide a method of controlling plant diseases that is safe for humans, livestock and beneficial plants. A still further object of the present invention is to provide a method of controlling plant diseases that is environmentally acceptable. Still yet another object of the present invention is to provide a method of controlling plant diseases that provides a means of preventing pathogen resistance. Still another object of the present invention is to provide a method of controlling plant diseases that does not require direct contact between the pathogen and the control agent. Still yet another object of the present invention is to provide a method of controlling plant diseases that can be administered in one dose. Other objects and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, drawings and claims.