• Shallow scab – corky tissue which arises from abnormal proliferation of the cells of the periderm of the tuber
• Lesions vary in size and shape and darker than the healthy skin
• Corky lesions 1 to 3mm deep and darker than shallow lesions
• Actinomycete attacks young tubers at a early stage of development

• Actinomycete conidia – produced by formation of septa, which contract to form narrow isthmuses between the cells
• Conidia- cylindrical and hyaline

Mode of spread and survival :

• Affects cabbage, carrot, eggplant, onion, radish
• Contaminated soil and infected tubers - source of infection
• Pathogen may survive passage through digestive tract of animals and hence it may spread with farm yard manure

• Use disease free planting materials
• Soil application of PCNB (30kg/ha) at the time of planting
• Green manuring before planting – effectively reduce disease incidence
• Seed treatment - mercuric chloride 0.1 %
• High degree of resistance - S. caldasii var. glabrescens, S. chacoense & S. commersonii
• Varieties - Menominee, Russet Rural, Sebago