VIEW ARTICLE

Growth of the Sporulating Zone of Puccinia striiformis and Its Relationship to Stripe Rust Epiphytology. R. G. Emge, Research Plant Pathologist, Plant Disease Research Laboratory, Agricultural Research Service, U.S. Department of Agriculture, P.O. Box 1209, Frederick, Maryland 21701; C. H. Kingsolver(2), and D. R. Johnson(3). (2)(3)Supervisory Plant Pathologist, and Agricultural Research Technician, respectively, Plant Disease Research Laboratory, Agricultural Research Service, U.S. Department of Agriculture, P.O. Box 1209, Frederick, Maryland 21701. Phytopathology 65:679-681. Accepted for publication 22 January 1975. DOI: 10.1094/Phyto-65-679.

Sporulation zones of Puccinia striiformis were measured daily for 5-12 days on several cultivars of wheat at different growth stages in the greenhouse and field. The sporulating zones showed a definite and continuing increase in area over time. The growth of the measured lesions was linear during the measurement period, but the rate of growth of the lesions on certain cultivars appeared to decrease with maturation. The characteristic of lesion enlargement permits an intensification of disease in the absence of conditions conducive to reinfection and profoundly affects the epiphytological aspects of the disease.