Evaluation of Possible Effects of Acid Rain on Scleroderris Canker of Red Pine in New York

Abstract

The possible affects of acid rain on Scleroderris canker of red pine were evaluated through two procedures. In the first, red pine seedling field plots, protected and unprotected from natural rain, were exposed to natural inoculum and treated with either deionized distilled water (pH 5.6), artificial acid rain (pH 3.5), or lime. Acid rain treatments did not increase disease infection levels over distilled water or lime treatments. Soil pH was slightly lowered by acid rain treatments. The second procedure evaluated pH and buffering capacity of red pine bark and buds from twelve plantations in the Adirondack region of New York. In addition, soil pH and soil cation content of the stands were determined and evaluated in relation to bark pH and natural Scleroderris canker disease increase rates. The effect of acid rain on red pine bark is probably minimal since bark surfaces were generally more acidic than acid rain. Buffering capacity against acid was small. Soil pH and spring bark surface pH were found to be inversely correlated with disease increase. These two procedures generated contrasting interpretations: (1) Scleroderris canker disease did not increase in response to artificial acid rain treatment of seedlings; (2) Scleroderris canker disease increase rate in red pine stands was somewhat related to soil pH. None of these relationships are very strong, and, therefore, it would appear that the various interacting factors of acid rain on the system generate a neutral minor impact on the Scleroderris disease problem in New York.