Temperature and Humidity Effects on Uredospore Viability

Abstract

Uredospores of Uromyces phaseoli typica were exposed in salt solution vessels to 6 temperature (5-33.5[degree]C) and 4 humidities (31-95.5%) at each temperature and sampled and tested for germination and infectivity 7 times during a period of 123 days. Temperature, humidity, and handling of spores were carefully controlled and a quantitative inocula-tor used in infectivity studies. Longevity, as tested by germinability, was inversely proportional to temperature and humidity, low temperature and humidity each favoring longevity. Previous reports had indicated the same temperature effect but had indicated optimal numidity of storage of about 50%. Infectivity of stored spores was highly correlated with their ability to germinate indicating that a spore capable of germinating probably possesses sufficient germ tube vigor to accomplish infection.