RootShield® Granules Biological Fungicide is a preventative biological fungicide for control of soilborne plant pathogens and plant root diseases. The active ingredient is a microbe, Trichoderma harzianum Rifai strain T-22, which when applied as an inoculant to soil or planting mixes, grows onto plant roots as they develop and provides protection against plant root pathogens such as Pythium, Rhizoctonia, Fusarium, Cylindrocladium and Thielaviopsis.