First report of Pyricularia oryzae, the cause of blast disease in upland rice, in Lombok, West Nusa Tenggara, Indonesia

Abstract

Rice (Oryza sativa L.) is a main crop cultivated by farmers in Indonesia. The demand for rice has increased, but rice production has decreased due to attacks by plant pests, including pathogen blast disease. This research aims to (i) describe the symptoms of blast disease in upland rice in Lombok, (ii) determine the incidence of blast disease in upland rice in Lombok, and (iii) identify the pathogen that causes blast disease in upland rice in Lombok. The research was conducted in Lombok, West Nusa Tenggara. Samples were taken randomly from the dryland area cultivating rice crops, which found 50 locations potentially attacked by blast disease. At one location, three samples of rice crops with blast symptoms were randomized by walking zigzag, resulting in 150 samples of rice crops. Samples were labeled and stored in plastic bag sampling, isolated, and identified at the laboratory. The study results showed that the macroscopic characteristics of rice leaves affected by blast disease could be seen from brown spots and points like a rhombus; the edges are brown and grey or whitish in the center of the spots, and the pathogen-produced white mycelium with a fine structure. In contrast, microscopic characteristics showed that the shape of the hyphae was septate, the structure of conidiophore with autophagic cell death, long pyriform microconidia, and long pyriform septate macroconidia. Based on 18S rRNA gene analysis, the Blast Lombok isolate had a DNA fragment of ±550bp. Based on these results, it can be concluded that the cause of blast disease in upland rice in Lombok, West Nusa Tenggara, is Pyricularia oryzae.