Seed diseases have become a major problem in Pennsylvania. Brown spot Also known as Septoria leaf spot, brown spot is a foliar disease that under severe conditions can lead to rapid defoliation of the soybean plant. Soybean varieties resistant to the disease are not available. Control recommendations include plowing under crop residues soon after harvest, planting disease-free seed, and rotation to other crops. Brown stem rot The occurrence of this disease appears to be increasing in Pennsylvania.
Losses occur because of reduced numbers and size of the seed and lodging of infected plants.
External symptoms usually are not visible until late in the growing season. The lower portion of the diseased stems turns a dull brown color, followed by rapid dying of the leaves. The fungus responsible for this disease overwinters in the soil and in soybean debris. Severity appears to be greatest when cool weather occurs during pod fill followed by hot, dry weather. Rotation to a nonsusceptible crop is a recommended control method.