Symptom

• The stems develop water-soaked spots which later may be covered with a cottony white growth.
• As the disease progresses, affected portions of the stem develop a bleached appearance, and eventually the tissues shred.
• Girdling of the stem results in premature ripening and in lodging of plants.
• Hard black bodies, the sclerotia, are formed inside the stem and occasionally on the stem surface. Basal stalk infections rarely occur.
• Yield loss of 10 to15% has occurred in Saskatchewan, Manitoba and North Dakota; occasionally losses of 50% have occurred in Manitoba

Management

• Crop rotation helps reduce disease carryover but does not eliminate airborne spores from another field.
• Clean seed to remove shrunken seed that may be infected with black spot and have low viability.
• Use seed with high germination (over 90%). Swath badly infected crops early to minimize shattering losses and seed shrinkage due to black spot.