Bacterial leaf blight Causal organisms: Bacteria Important species: Bacterial blight of bean (Xanthomonas axonopodis pv. phaseoli) Bacterial blight of cotton; Angular leaf spot of cotton (X. axonopodis pv. malvacearum) Bacterial leaf blight of rice (X. oryzae pv. oryzae) Bacterial leaf streak of rice (X. oryzae pv. oryzicola) Bacterial leaf blight of tomato and pepper (X. campestris pv. vesicatoria) Cassava bacterial blight (X. campestris pv. manihotis) Cassava leaf spot (X. cassavae) Bacterial blight of soybean (Pseudomonas savastanoi pv. glycinea; P. syringae pv. glycines) Host plants Beans, cassava, cotton, cucurbits, rice, tomato, pepper, plantain, and many other secondary host crops Affected plant stages All growth stages Affected plant parts Leaves, pods, and fruits Symptoms Bacterial leaf blight of rice An infected leaf has yellow watersoaked lesions at the margin of its leaf blade. The lesions run parallel along the leaf and when they join together may cover the whole leaf. Bacterial discharge appears on young lesion early in the morning that looks like a milky dewdrop. As the disease progresses, the leaf dries-up with white lesions and the leaf blade has wavy margins. Bacterial leaf streak of rice Infected leaf has narrow, dark-green, watersoaked streaks of various lengths initially found on the leaf blade during tillering and booting growth stages. As the disease progresses, the streaks turn to yellowish-gray and transparent. Bacterial discharge appears as numerous yellow beads on the surface of the lesion. In its advance stage, the lesions turn brown to grayish-white and they remain linear on the leaf margins. Conditions that favor development Warm temperature, frequent rain, and high humidity Over-crowded plants with poor air flow and low sunlight penetration among plants Improper soil nutrient and irrigation management Poor soil drainage Diseased-seeds and planting materials Preventive control Crop rotation with crops that are not susceptible to the bacteria Use of diseased-free seeds, diseased-free planting materials and cuttings, and use of resistant cultivars. Hot water seed treatment Proper fertilization and water management Proper land preparation for better drainage Proper plant spacing for proper air circulation and sunlight penetration within plants Insect pest control as they may serve as the carrier of the bacteria Weed control No farm activities when plants are wet Clean farm tools Field sanitation Removal and proper disposal of infected plant parts Deep plowing to bury plant debris and followed by fallowing the area Lemongrass extract Mint extract
Posted on: Thu, 23 Oct 2014 18:45:48 +0000
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