Injury to Eastern White Pine by Unidentified Atmospheric Constituents

Abstract A general decline of Pinus strobus L. in the Cumberland Plateau of Tennessee was determined, by an aerial survey, to be in the Kingston-Oak Ridge-Rockwood-Harriman industrial area. This disease, called post-emergence chronic tipburn, was also found in other industrial areas, includingsome which contained coal-burning power plants. Root and stem isolations yielded no primary pathogens. Pruning and fertilizing sometimes brought about improved vigor, but did not affect occurrence of needle tipburn, a primary symptom. Diseased trees transplanted out of the affected area recovered,while trees transplanted within the affected area continued to decline. Trees differed greatly in their susceptibility to the disease. Scions from susceptible trees displayed symptoms year after year even when grafted to resistant trees in the affected area. Scions from resistant trees continuedto be disease-free year after year even when grafted to diseased trees. The grafting experiment furnished evidence that a virus was not involved and indicated that the cause of the trouble was an atmospheric agent. Members of susceptible clonal lines potted with the same soil mixture wereinjured when placed in the affected area, while others remained disease-free outside. This use of susceptible clones as biological indicators gave further evidence that the disease causal agent is atmospheric and that the level of resistance is genetically controlled. Analyses of diseasedfoliage showed that injury could occur without causing a conspicuous elevation of either sulfur or fluorine in needle tissues. Sulfur dioxide and fluorine are still regarded as possibly involved.