Production of conidia and appressoria by Cordana johnstonii on banana

Cordana johnstonii started to produce conidia on banana leaf spots about 1 d after wetting and, under moist conditions, continued sporulating at a constant rate for another 5 d at least. The optimum temperature for conidial production (T opt ) was 21 °C. At 22°, 0·04 conidia mm −2 of lesion h −1 were produced on dead leaves, but on living leaves production was 0·3-2·3 conidia mm −2 h −1 Conidial survival was affected by dryness, with half-lives averaging 53 h on moist leaves and only 10 h on dry leaf surfaces. On detached banana leaves, most appressoria were produced at 22–25° but some were produced at temperatures as low as 10° if leaves were wet. Statistical models were developed to describe the relationships between production of conidia and appressoria and duration of leaf wetness and incubation temperature.