ABSTRACT
Sclerotinia stem rot is one of the most destructive soybean diseases in Brazil. It is found in the states of the Minas Gerais, Parana, Rio Grande do Sul and Santa Catarina. The first severe outbreak of the disease was recorded during the Parana 1976–77 crop season. The disease is most severe in the states of Minas Gerais and Parana at altitudes above 800 m where there is abundant rainfall during the crop season and temperatures are mostly in the range of 15 to 28 C, these conditions being optimum for apothecial production. The incidence of Sclerotinia stem rot is dependent upon favorable weather conditions, but is also greatly influenced by plant population. Preliminary studies on biological control of S. sclerotiorum have shown that a species of Trichoderma fungus applied in the soil or by seed treatment can help reduce incidence of the Sclerotinia stem rot.
