Rhizoctonia stem canker

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Causal organism: Thanatephorus cucumeris (Frank.) Donk. (teleomorph) and Rhizoctonia solani Kühn (anamorph)

Other names: damping off, Rhizoctonia sprout rot, rootlet rot, root rot, Rhizoctonia rot, collar rot

Diagnostic summary

  • What you see on plants

- in seedbeds, the most obvious symptom is the presence of water- soaked sunken lesions, in the stems of seed sprouts, near the soil line. The stem cortex decays causing stunting and yellowing.

- taproot and lateral small roots have black cankers that may lead to seedling death.

  • More common in seedbeds.  Healthy plants in the field rarely develop symptoms.

  • R. solani is extremely widespread,  but its effect on sweetpotato had only been recorded in the United States.


Economic importance

Geographical distribution



Biology and ecology

Host range



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