Uredospore production and sporulation period of Puccinia recondita f. sp. triticina on primary leaves of wheat

Abstract

Uredospore production per day and per sporulation period was measured under near-optimal conditions. Pustule density influenced time and rate of pustule opening, size of pustules, time of maximum sporulation, length of the sporulation period and the time and rate of tissue necrotisation. Within limits total dry weight of spores per leaf per sporulation period was independent of pustule density; it roughly equalled the dry weight of the spore producing leaf. The longest sporulation period observed was 65 days; at low pustule densities secondary pustules replaced exhausted primary pustules. Infectivity of the spores was normal up to 46 days after inoculation. The long sporulation period was epidemiologicaly interpreted as a survival mechanism.