STUDIES IN ASCOCHYTA PISI LIB.

Abstract

The existence in peas of both physical and physiological resistance to attack by Ascochyta pisi was indicated. Infection was possible at constant temperatures ranging from 45 to 80° F. The temperature subsequent to incubation had a marked effect on infection: the appearance of the symptoms was delayed and the number and size of lesions were increased at the lower temperatures. A. pisi can utilize nitrate, ammonium, amide, and amino nitrogen. Growth is dependent upon both pH and the nitrogen source. A wide variety of carbon sources can be utilized by A. pisi but the isolates differ with regard to their abilities to utilize the different carbon sources. The pH of the medium is of importance at the initiation of pycnidial production. Exhaustion of the carbon supply is apparently a factor in the initiation of sporulation.