Seedling Disease (fungi - Pythium spp. and Rhizoctonia spp.): Seedling blight kills the young plants either before or just after emergence, resulting in a reduced stand. Post-emergence attacks cause the seedlings to collapse and die soon after emergence. Seedling diseases are especially damaging during periods of adverse conditions, such as cool, wet weather. Improper planting such as covering the seed too deeply, also increases seedling blight.