Symptoms are also known as rice white tip blight. The main damage leaves, the disease began at the tip or leaf edge, and then spread down along the edge or middle of the leaf, forming a stripe. The lesions were dark green, gray-brown and finally white. There are brown stripes at the border between disease and health, and the diseased part is easily broken and broken. Severe leaves can cause dead. After the damage to rice, the formation of dark brown spots on the glume, the center was gray-brown lesions, sick valley thin.
Pathogen Phoma oryzicola Hara = Phyllosticta oryzae Hara said that the rice stem fungus, is a fungus of the fungus Subgenus fungus. The conidia were buried under the epidermis of rice leaves and exposed slightly, dark brown. The spore-forming cells were single-celled, unbranched, and the sporulation pattern was a full-wall sprout-single-synthetic format. Conidia Oval, single cell, colorless, size 2.8-7.02.8-3.9 (Î¼m). Conidia have 1-2 oil balls. The sexual state is Tromatosphaella oryzae (Miyake) Pawick, which is called Asychrophyte Subgenus Fungi.
Transmission Pathways and Pathogenic Conditions The pathogenic bacteria overwinter in diseased leaves and diseased glume with conidia. There are more than 10 grassy weeds on the host of the pathogen, so weeds can also be transmitted. The conidiospore of wintering conifers released conidia under suitable conditions, spread to the leaves of rice by wind and rain, and invaded through the central wounds of leaves, leaf margins or leaves. From the jointing stage to the booting stage, the episode became apparent and the second incidence peak appeared at the early stage of grouting. During this period, low temperatures, rain, and more typhoons are conducive to disease. After the storm, rice leaves cause a lot of wounds, and the disease easily occurs. Excessive nitrogen application, too late onset, and milder onset of silicon. Rice late in the tiller did not promptly dry the field, causing more water and heavy onset. The field density is high and the disease is heavy. Onset temperature 25-28Â°C, mycelial growth temperature 10-35Â°C, optimum 22-25Â°C, conidia formation temperature limit 15-30Â°C, optimum 25Â°C, spore germination temperature limit 10-35Â°C, The optimum temperature is 30Â°C.
Prevention methods (1) Strengthen seed quarantine and prevent the introduction of disease-free areas. (2) Selection of resistant varieties, japonica rice is more resistant than japonica rice. The tall stalked and long-leaved cultivars were more susceptible. Indica Rice No. 3, No. 4 and No. 3, 3037, Nannong 3005, Xingyi No. 1 were more resistant to disease. (3) Apply organic fertilizer, increase phosphorus and potassium fertilizers and silicon fertilizer. The tillering period should be timely, moderately dry, and dry and wet during the late growth period. Cultivation must not be too dense and reduce the humidity in the field. (4) Chemical control. Seed treatment with 50% carbendazim or 50% thiophanate-methyl wettable powder 250-500 times soaking seeds for 24-48 hours, 40% 250-500 times soaking wet superfine powder 250 times soaking seeds for 24 hours, the effect is good. From booting to heading and flowering stage in rice, 40% carbendazim gel suspension 40 ml or 40% dry powder wettable powder 60-75 g was used after the central strain was found. Spray 60L per 667m2 of water. 40% ç¦¾ ç¦¾ ç¦¾ ç¦¾ çµ çµ ç¦¾ ç¦¾ ç¦¾ å…¼ å…¼ å…¼ å…¼ å…¼ å…¼ å…¼ å…¼ å…¼ å…¼ å…¼ å…¼ å…¼ å…¼ å…¼ å…¼ å…¼ å…¼.
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