Potato scab is caused by a bacterialike microbe called Streptomyces scabies. Infected potato tubers develop a roughened, corky surface and pits in the skin due to this disease. Scab is favored by high soil pH and recent applications of manure or organic matter.
Choose to grow scab-resistant varieties. Maintaining adequate soil moisture during tuber development is critical. Soil pH should be between 5.0 and 5.3 to help prevent scab. Turn under applied organic matter well in advance of planting. Use crop rotation, avoiding scab-infested parts of the garden for three to four years. Plant only disease-free seed pieces.
