Deterioration of uredospores of wheat stem rust under natural conditions

Abstract

Uredospores of wheat stem rust were mixed with three types of soil and placed in the field under winter conditions. Germination of these uredospores ceased between 14 and 62 days. Cytoplasmic deterioration, with the development of spherical bodies, began in 16–21 days and was complete in 23–65 days. The spherical bodies, small in the beginning, enlarged in size and decreased in number, finally disappeared leaving only a small amount of granular material on the spore interior. After six months, the cytoplasmic membrane had disintegrated, the exospore began fading and disintegration of the exospore commenced. The disintegration process is apparently rather slow since exospores were discernible for as long as two years after being placed in the soils. The significance of the spherical bodies was undetermined.