VIEW ARTICLE

Comparative Effects of Alternaria alternata Infection and Other Leaf Injuries on Growth of Tobacco. J. R. Stavely, Research Plant Pathologist, Tobacco Laboratory, Plant Genetics and Germplasm Institute, Beltsville Area, Northeastern Region, ARS, USDA, Beltsville, Maryland 20705; L. J. Slana, Agricultural Research Assistant, Plant Pathology, Tobacco Laboratory, Plant Genetics and Germplasm Institute, Beltsville Area, Northeastern Region, ARS, USDA, Beltsville, Maryland 20705. Phytopathology 63:495-499. Accepted for publication 7 October 1972. DOI: 10.1094/Phyto-63-495.

Postinoculation measurements of leaf growth, stem elongation, and time until flowering were made on ‘Coker 187-Hicks’ tobacco plants that were inoculated with Alternaria alternata or Colletotrichum destructivum or mechanically injured. When young leaves were heavily inoculated or wounded, subsequent expansion was inhibited. A. alternata, C. destructivum, severe wounding, and removal of most or two to four of the youngest leaves caused an increase in the rate of subsequent growth and resulted in significant increases in the numbers of leaves per plant at 14 and 28 days after treatment. However, only plants affected by A. alternata, severe wounding, or removal of most leaves had significantly more leaves than controls by the flowering date. These three treatments delayed flowering, but the delay was less with A. alternata than with the other two treatments. All treatments except removal of two to four of the youngest leaves inhibited stem elongation in the area treated. All treatments except severe wounding or removal of most leaves inhibited stem growth above the treated area. The results suggest that A. alternata infection caused both nonspecific and specific effects on growth of the tobacco plant.