The effect of temperature on development of soybean rust (Phakopsora pachyrhizi)

Abstract

Uredospore survival and the development of soybean rust were examined across a range of temperatures. To determine the effect of temperature on uredospore survival, samples of dry uredospores were exposed to each of a series of eight temperatures for 8 h prior to a germination test on water agar at 21°C for 4 or 16 h. Germination was significantly reduced when uredospores had been exposed to temperatures of 28.5–42.5°C. Development of rust in soybeans was examined under four temperature regimes. Following inoculation with uredospores, plant foliage was sprayed with water and kept under conditions of dew at 21°C for 16 h. Plants were then placed in a selected regime. The 17–27°C regime provided the best conditions for rust development. These findings may partially explain some of the observations on rust occurrence in the field.