Abstract: A novel fungal protein which is effective for inducing or stimulating the defense responses of plants against disease is disclosed. This protein, which is also referred to as an elicitor protein, may be used for the treatment or prevention of fungal infections in plants. The protein is produced by culture of Trichoderma virens, and may be subsequently recovered from the culture medium and purified.

Abstract: A process for producing strains of Trichoderma virens which are deficient for production of viridiol for use as biocontrol agents is disclosed. These mutant strains are produced by treatment of viable T. virens with chemical or physical mutagens, preferably by irradiation with ultraviolet light. The treated fungi are then screened for production of viridiol to select for deficient strains. Following recovery, the mutant strains may be used as biocontrol agents for the control of plant diseases by application to the locus of a plant, seedling or seed to be protected. Coating seeds with the biocontrol agent prior to planting has been found to be particularly effective for the control of soilborne root or seedling diseases.

Abstract: Purified bacterial strains that are effective for the inhibition of plant pathogens, including the fungi Rhizoctonia solani and Pythium ultimum have been isolated. These strains are useful as biocontrol agents, and can be used to produce antifungal metabolites, such as antibiotic compounds, active against the plant pathogenic fungi Rhizoctonia solani and Pythium ultimum. Both the purified bacterial strains and the antibiotic compounds can be used as active agents for biocontrol compositions.

Abstract: A process for producing cultures of Gliocladium virens for use as biocontrol agents wherein the production of viridiol is inhibited. Cells of Gliocladium virens are grown in a culture medium and under conditions effective to produce gliotoxin and/or gliovirin, wherein the culture medium includes an amount of a fungicidal steroid inhibitor which is effective to inhibit production of viridiol but which does not substantially inhibit the growth of G. virens. Following recovery, the resultant culture may be used as a biocontrol agent for the control of plant diseases by application to the locus of a plant, seedling or seed to be protected. Coating seeds with the biocontrol agent prior to planting has been found to be particularly effective for the control of soilborne root or seedling diseases.