Severity of Rice Disease Caused by Curvularia Spp In Malaysia

Abstract

Curvularia is a hyphomycete fungus that is a facultative pathogen that affects many plants species especially in the tropical region. Rice researchers have documented Curvularia as one of the 6 main pathogenic fungi that infects and attacks rice. The fungus belongs to the Ascomycota phylum, from the Euascomycetes class. This pathogenic fungus causes diseases such as black kernel, speckled rice, sheath rot and sheath blight in rice worldwide. According to the International Rice Research Institute, IRRI, this disease has caused loss in yield in countries such as India, Indonesia and Thailand. Recently, Curvularia species has been isolated from all our infected or disease tissues sampled from field. In order to determine how much of the disease severity is caused by this pathogen only, we used our field isolate of Curvularia to examine disease symptoms attributed by this single pathogen on rice as host. The objective of this study is to perform a screening of rice varieties and determine level of disease severity and incidence caused by the Malaysian strain, Curvularia spp (PMLI-1). The fungal plug inoculum method was used in this study. The resulting disease symptoms were observed and recorded based on a disease symptoms scale. Based on the disease scale and the resulting symptoms, the study found that out of the 21 rice varieties used, three varieties showed high level of resistance to Curvularia spp infection, six varieties were resistance, and eight varieties of rice showed moderate resistance. Three varieties showed susceptibility and one variety showed high levels of susceptibility to Curvularia spp. Rice varieties that showed high resistance to infection of Curvularia spp are UKMRC9, UKMRC2, and Oryza nivara.