First Report of Bipolaris oryzae on Typha latifolia and the Pathogenicity of Its Isolates on Different Rice Varieties

Abstract

Rice ( Oryza sativa L.) is the staple food of more than half of the world population. However, its production is facing several biotic constraints. Among serious biotic factors that harm rice crops, the Helminthosporium disease has severe adverse impacts on rice yield, generating heavy losses of up to 90%. Four Bipolaris oryzae isolates were recovered for the first time from leaf lesions in the weed species Typha latifolia , and then subjected to pathogenicity tests on several rice varieties. The results indicated that Moroccan isolates of B. oryzae altered the leaf surface of five rice varieties tested. Among four isolates, Hor4 was the most pathogenic, showing high aggressiveness on the Cererrer and Elio varieties, with disease severity of 92.59%, followed by the Hor1, Hor2, and Hor3 isolates. The Arpa variety showed higher resistance to the Hor1 isolate, with a severity index of 35.18%. Through mycelial cutting or conidial suspension, B. oryzae isolated from T. latifolia was able to produce conidia on the leaves of this weed species.