Leaf Streak In Rice Research Articles

Mode of Infection in Bacterial Leaf Streak of Rice and Histology of the Diseased Leaf1)

Mode of Infection in Bacterial Leaf Streak of Rice and Histology of the Diseased Leaf¹)

Mode of Seed Infection and Transmission of Bacterial Leaf Streak of Rice

Mode of Seed Infection and Transmission of Bacterial Leaf Streak of Rice

Epidemiology of Bacterial Leaf Streak of Rice

Studies were conducted on the perpetuation and host range of the rice leaf streak pathogen Xanthomonas translucens f. sp. oryzae (Fang et al.) Pordesimo (=X. oryzicola Fang et al.) and the factors affecting the disease.Seeds from a diseased crop when sown newt season, developed diseased seedlings under field as well as laboratory conditions. The bacterium was isolated from these seedlings and its pathogenicity was confirmed. No diagnostic symptom attributable to bacterial infection was detected on such seeds, nor the bacterium could be isolated. The bacterium did not perpetuate in infected debris. Even in the leaves and bacterial beads stored under room conditions, the bacterium remainedviable upto 90 and 75 days respectively. The bacterium did not infect any of the 30 grasses, 8 cereals and millets including maize and 4 species of Cyperus.The young rice leaves were more susceptible to the disease, and became resistant with age. Two to three continuous days with high humidity (R.H. 83.0-89.5%) or dew during morning hours were necessary for infection. The lesion enlargement was favoured by moderate temperatures (26.1-30.5°C) and retarded at lower range (below 22.4°C), irrespective of relative humidity.

Xanthomonas oryzicola . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Xanthomonas oryzicola . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On Oryza saliva . Some weed species of Oryza have also been reported to be susceptible (45, i789). Weakly pathogenic to Leersia hexandra by artificial inoculation. DISEASE: Bacterial leaf streak of rice. Narrow, dark greenish, water-soaked streaks of various lengths appear between the veins. Minute amber droplets of bacterial exudate are commonly found on these lesions. Later the lesions extend and coalesce giving large brownish patches. In the late stages symptoms are difficult to distinguish from bacterial leaf blight. GEOGRAPHICAL DISTRIBUTION: Confined to tropical Asia. Reported from China, India, Philippines, Thailand and West Malaysia (CMI Map 463 and 49, 144).TRANSMISSION: The pathogen spreads within a crop in surface moisture and may enter the leaf through minor abrasions or stomata. Warm wet weather is favourable to both spread and development of the tisease. Introduction into new areas can occur in seed from infected plants (48, 1693).

White leaf-streak of rice caused by Ramularia oryzae sp.nov.

Ramularia oryzae sp.nov. is described, causing a white leaf-streak of Oryza in Papua and New Guinea, British Solomon Islands Protectorate, North Borneo, Sierra Leone and Nigeria.