Epidemiology of rice blast disease in Egypt

الملخص EN

Institute of Plant Pathology, Agriculture Research Center and Botany Department*, Faculty of Science, Cairo University, Egypt.

An epidemic outbreak of blast disease (Pyricularia oryzae Cav.) occurred on Reiho rice variety during 1984.

The rate of disease spread (r) in Reiho variety ranged from 9.630% to 11.515% in six rice producing governorates, while the (r) value in Giza varieties ranged from 1.324% to 2.661% in the same governorates.

The average yield of Reiho variety was between 0.721 and 1.932 ton/fed-dan in the six governorates, while it was between 2.124 and 2.593 ton/feddan for Giza varieties in these governorates.

The temperature and relative humidity possessed no significant effects on the spread of the disease.

On the other hand, the number of spores trapped, dew period and wind velocity showed significant effects.

The number of blast lesions on the leaves of Reiho variety was four-folds as those appeared on the leaves of Giza 171 and Giza 172 varieties.

Sporula-tion of the pathogen on Reiho variety was four-folds as that on Giza 171 variety and two-folds as that of Giza 172 variety.