There are various symptoms associated with damping off; these reflect the variety of different pathogenic organisms which can cause the condition. However all symptoms result in the death of at least some seedlings in any given population. Groups of seedlings may die in roughly circular patches, the seedlings sometimes having stem lesions at ground level. Stems of seedlings may also become thin and tough ("wire-stem") resulting in reduced seedling vigor. Leaf spotting sometimes accompanies other symptoms, as does a grey mold growth on stems and leaves. Roots sometimes rot completely or back to just discolored stumps.
Damping-off occurs primarily in the seedbed, when it is too cool and too wet. This disease is caused by various soil-inhabiting fungi, especially Pythium species and Rhizoctoniu so&i. The seedlings may be attacked either before they emerge, causing a reduction in emergence, or after they emerge, causing the plants to wilt, fall over, and die Occasionally, large groups of seedlings in beds are destroyed, especially if untreated seed was planted in unsterilized soil.
