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The scientific literature is filled with conflicting reports on the development of the common scab disease of potatoes and its causal organism. One unresolved question is soil reaction, once thought to be the answer in controlling this disease. Scientific studies an d practical experience over a long period had shown that acid soils having a pH of approximately 5.3 or below usually did not support common scab development, though sporadic and unexplained reports of disease occurrence in these soils were observed. In the late 1950s, however, such reports became more frequent in Maine and before the mid-1960s, losses relate d to scabb y potatoes growing in acid soils were common. Throughout this period overall crop losses from the disease were minimal even though individual growers sometimes lost a large par t of their crop. During the dry 1970 growing season, however, a disease survey estimated that up to 5% of the Maine crop was scabby. Studies of this new form of scab and observations on its development within the state are reported herein.
Life Sciences and Agriculture Experiment Station
Agronomy and Crop Sciences
Manzer, F.E., G.A. McIntyre, and D.C. Merriam. 1977. A new potato scab problem in Maine. Life Sciences and Agriculture Experiment Station Technical Bulletin 85.