How to Manage Pests
Pests in Gardens and Landscapes
Common scab—Streptomyces spp.
Common scab lesions are usually circular and 6 - 8 mm in diameter, but they can be smaller in early stages
of development and larger if they coalesce. Lesions typically possess a raised margin and slightly depressed
center. Scab may appear on tubers as superficial tan to brown corky lesions or beneath the tuber surface
as lesions with depressions. Lesions may also be cushionlike or warty.
Common scab is largely cosmetic; affected tubers are edible.
Many varieties are resistant. If scab occurs, change varieties
in the next year. The disease is favored by neutral to basic
soil; sulfur may be worked
into the soil to make it slightly acidic and thus reduce disease.
corky lesions of common scab
beneath tuber surface