Black Scurf/Rhizoctonia Canker
Rhizoctonia solani

• Delayed or no emergence, have few stems, and poor growth
• Underground stems and roots have brown, sunken dry spots
• Small hard black spots stick to the skin of the tuber like dirt that won't wash off
• Tuber production is low, tubers may be small and deformed
• In severe cases, small green tubers form on the stem above ground
• Stem has a white to gray flaky growth just above the soil line.
• Most problematic in cool wet soils
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