000 macroconidia per gram of sand sclerotia material use of sporidesmium in the biological control of plant pathogens and plant disease in general the procedure consists of adding an inoculum of sporidesmium sclerotivorum furnished in a sand sclerotial mixture to soil which contains sclerotia of the plant pathogen which for laboratory experiments is artificially added to field soil containing sclerotia of the plant pathogen produced under natural conditions the material is mixed into the soil and the mycoparasitism is permitted to develop in fallow soil for at least 10 weeks preferably at beneficial soil temperatures of 15 u00b0 25 u00b0 c a soil ph of 5 0 to 8 0 and moisture levels of 70 of field capacity or higher under the conditions we used in our field experiments we obtained good results by allowing the mycoparasite to develop in the soil for 20 weeks however there is no reason why this time period cannot be shortened by altering the conditions macroconidia of sporidesmium germinate in the soil immediately adjacent to individual sclerotia the germ tubes elongate and by mechanisms unknown penetrate the sclerotia sclerotia thus infected gradually become consumed by the mycoparasite and eventually become completely destroyed the beneficial result of this destructive process is the decrease or elimination of sclerotia in the soil which can cause plant disease a natural slit loam was moistened to 70 of field capacity and artificially infested with sclerotia of sclerotinia minor at the rate of 1 by weight and added to beakers in 150 g quantities four replicate beakers of the soil were treated with sporidesmium by the addition of 1 5 g of moist sand sclerotia cultures of the mycoparasite followed by mixing four replicate beakers of the soil were kept as controls for comparison soil temperature and ph.