We've been using MST for several years to help control rhizoctonia or "black scurf" and other soil diseases on our potatoes and have seen greatly improved control. MST combines plant-friendly fungi, including mycorrhizae and bacteria, in a dry nutrient package. For use on all crops, whether in a potting soil, directly with transplants, or in the planter box with the seed. Recommended rate is 1-2oz/100# seed potatoes; 4-8oz/100# of other seed. OMRI-A.