Incubation period as a measure of infection efficiency for isolates of leaf blast pathogen in pearl millet and rice is an important parameter to testify host specificity as well as resistance against the pathogen. Incubation period (IP₅₀) for leaf blast symptom development on pearl millet and rice using respective isolates (pearl millet isolate on pearl millet and rice isolate on rice) were estimated to be 4.98 and 6.23 days respectively at 26±1°C. Infection efficiency estimated from the IP₅₀ was 0.2040 and 0.1605 respectively and indicated pearl millet is the better host for the pathogen. In cross infectivity test isolates from pearl millet and rice had shown significantly higher ratio of number of appressorium to conidia on pearl millet host compared to rice host where lower ratio of number of appressorium to conidia were recorded. It appeared that blast conidia germination, germ tube growth, appressorium formation are influenced by host surface difference.

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