RootShield from BioWorks is a biological fungicide containing the active ingredient Trichoderma harzianum strain T-22. It is effective against Pythium, Rhizoctonia, Fusarium, Cylindrocladium and Thielaviopsis. It is available granular and wettable powder formulations. One application provides up to 12 weeks of protection and costs less than 1-2 cents per 6-inch pot. It has a zero re-entry interval and is OMRI listed and is a VeriFlora Approved Input Material.