Disease Directory

    Scab (Potato)

    Streptomyces scabies, S. acidiscabies, S. turgidiscabies

    Bacteria
    Roots

    Overview

    A soil-borne bacterial disease of potatoes causing rough, corky lesions on tuber surfaces. While primarily cosmetic, severe infections reduce marketability and storage quality.

    Symptoms

    Rough, corky, raised or pitted lesions on tuber surfaces. Lesions may be superficial or deep-pitted. Tuber skin becomes rough and cracked. Primarily cosmetic but severe cases affect peeling quality and storage.

    Environmental Conditions

    Dry

    Prevention

    Maintain soil pH below 5.5 (acidic conditions suppress the pathogen). Irrigate during tuber initiation. Use resistant varieties. Rotate with non-host crops. Green manure with buckwheat or rye.

    Management

    Lower soil pH with sulfur. Maintain consistent soil moisture during tuber development. Plant resistant varieties. Avoid fresh manure or lime before planting potatoes.