Bacterial Blight of Rice and Its Control

Symptoms are also known as white leaf mites, terrestrial fire, and thatch grass. The whole growing period can be affected. The seedling and childbirth period suffer most. All organs can be infected and the leaves are most susceptible to disease. The symptoms of the disease are different due to the invasion site of the bacteria, the disease resistance of the varieties, and the environmental conditions, which are commonly divided into 3 types.
(1) The leaf blight type mainly damages the leaves, and also seriously damages the leaf sheath. The disease starts from the tip of the leaf or the margin of the leaf. First, dark green water is immersed in the linear spots, and yellow-white lesions are quickly formed along the linear spots, and then along the On both sides of the leaf margins or in the middle ribs, it became yellowish-brown, and finally it was withered white. The boundaries of the lesions were clearly defined. In the disease-resistant varieties, the edges of lesions are irregularly corrugated. Diseased varieties of diseased leaves are grayish green, water loss is fast, and the inside volume is blue and dry, mostly manifested in the upper part of the leaves.
(2) Acute wilting type from seedling stage to tillering stage, pathogens are easy to attack when invading the vascular bundle from the root or stem base wound. When the main stem or more than two tillers occur at the same time, the heart leaves lose water and blight, withering and dying. The rest of the leaves have successively curled, and then the whole plant withers, and only the heart and leaves die. The stem of the diseased plant has a large amount of bacteria and pus. Some of the roots of the leaf sheath appear yellow-brown or brown. In some rice plants from the time of tilling to booting stage, the midrib of the flag leaf or its lower 1-3 leaves is yellowish, the lesions extend up and down along the midrib, the upper tip can reach the tip, the leaf sheath is released, and sometimes the leaves are folded, and the diseased plants die without heading. Brown spots or browning disease resistant varieties are more common. The pathogens are cut through leaves or wounds. In the low temperature or unfavorable disease conditions, brown necrotic reaction bands appear around the lesions, and the disease spreads stagnant.
(3) The jaundice-type jaundice symptoms are rare, early heart leaves do not wither, there are irregular chlorotic spots, after the development of dry yellow spots, diseased leaf base occasional water-soaked intermittent strips. When the weather is wet or when the morning dew is not dry, milky white dots are visible on the above-mentioned various types of diseased leaves, and after the drying, small yellow rubber particles are formed and it is easy to fall off.
The dead heart seedlings caused by bacterial blight in rice began to appear at the time of childbirth. Symptoms such as water loss, reeling, and blue and dryness appeared on the heart and leaves of the diseased plant or 1-2 layers below the heart, and eventually died. After the bacterial seedlings form with dry seedlings, the other leaves gradually shrink and shrink. Finally, the whole plant withers away. Peel the leaves of the new leaf or the broken stems or cut off the diseased leaves. Extrude hard and see yellowish white. Bacteria pus overflow, that is, pathogenic bacteria and pus, is different from the dead heart seedlings caused by the damage of big larvae, stem borer and stem borer.

pathogen
Xanthomonas oryzae is called Xanthomonas oryzae. Including Xanthomonas oryzae pv.oryzae (Ishiyama) Xanthomonas oryzae and Xanthomonas oryzae pv. oryzicola (Fang et al.) Rice Xanthomonas oryzae Lesion species, is a bacterium. Synonyms X.campestris pv.oryzae (Ishiyama) Dye. Bacterial strains of rice with Xanthomonas oryzae are short-barreled, 1.0-2.70.5-1.0 (μm) in size, solitary, single-flagellate, extremely polar or subpolar, approximately 8.7 μm long, 30 nm in diameter, and Gram-negative, Without spores and decidua, the bacteria are surrounded by extracellular polysaccharides that are viscous. Colonies of honey yellow on artificial medium produce insoluble yellow pigment, aerobic and respiratory metabolism, and the pathogenicity of strains in different regions is different. Under natural conditions, pathogenic bacteria can infect cultivated rice such as cultivated rice, wild rice, Lee's clam, and white clam. The serological identification of the bacteria was divided into three serotypes: Type I was dominant and distributed throughout the country. Types II and III exist only in individual rice fields in the south. The temperature limit for the growth of bacteria is 17-33°C, the optimum temperature is 25-30°C, the minimum temperature is 5°C, and the maximum temperature is 40°C. The pathogenic bacteria is most suitable for pH 6.5-7.0.
Transmission pathways and disease conditions The main seeds of primary infections were carriers of pathogenic bacteria, diseased rice straw, and diseased rice plants in the field. Weeds such as Lee's weeds can also be transmitted to the fields. Bacteria overwinter in the seeds, after sowing by the leaves holes, wounds invade to form a central diseased plant, diseased strains secrete yellow bacteria ball, by wind and rain, dew, irrigation, insects, human factors and other factors. The pathogens are far away from the irrigation water and wind and rain. Low-lying stagnant water, rain and flooding can cause contiguous disease. The morning dew dry field operation caused the spread of the bacteria. High temperature, high humidity, dew, typhoon and heavy rain are the epidemic conditions. Long-term water accumulation, excessive nitrogen fertilizer, excessive growth, and acidity of the soil in the rice area are conducive to disease occurrence. The incidence of mid-late rice is usually heavy, and japonica rice is heavier than japonica rice. Dwarf broad-leaved varieties are more important than high-stalked narrow-leaf varieties. Infertility resistant varieties are more important than fertilizer-resistant ones. Rice is susceptible to disease during young panicle differentiation and pregnancy.

Control methods
(1) Select 2-3 main plant resistant varieties that are suitable for the local area.
The early rice resistant varieties include: Jiayu 280, Japonica No. 61, No. 40, Yuzao, No. 81 Zhongyouzao, No. 21 and No. 22 Xiangzaojing, Peiliangyou 288, Guiyue 901. The mid-rice resistant varieties include: Jia 45, Xiushui 1067, Japonica 28, Japonica 32, 34, 36, 36, 38, 59, 61, Yuyouduo Line 1, Xiangjing 2 and 7 bags accounted for 1 No. 2, Baguizhan No. 2, Sanpeizhan No. 1, Hangyu No. 1.
Late rice resistant varieties include: Shennong 514, No.13, No.14, No.39, No.40, Ningshu No.15, No.16, No.17 and No.4 Ninglang. There are H301 strains in Shandong. Indica Rice Variety The seven resistant strains of bacterial blight (pathogenic type 1-7) in our country are: DP5165, 95 Jian 27, 45, 95 Jian 25, 96 Jian 35, Ning 93-38, Ningbo No. 2, Taiwan 537, D602, etc.
(2) Strengthen the phytosanitary quarantine, do not introduce from the ward, must be introduced, use 1% lime water or 80% 402 antibacterial agent 2000 times liquid soaking 2 days or 50 times formalin soaking 3 hours boring 12 hours After washing, germination. Soaking seedlings can also be used 2ml, 10-12L of water, fully stir 6-8kg after soaking rice seeds, soaking seeds for 36 hours after germination. Can also be used 100 times mycobiotin, heated to 55 °C, soaking seeds for 36-48 hours after sowing germination.
(3) Agricultural control, promoting the application of enzyme composted compost, strengthening water slurry management, shallow water ground irrigation, timely drainage after rain, drainage in the tillering period, and waterlogging in flooded fields. The diseased rice straw should be properly treated to prevent contact with germs, shoots, and seedlings, and to remove waste rice or weeds from Tanabe.
(4) Chemical control. After finding the central diseased strain, spray 20% Ye Kuning (Ye Qing Shuang) wettable powder, and use 100 g per 667m2. When 50L of water is used and the control effect of chloroprene is not enough, the application of phytarctin can be mixed with the sulfuric acid chain. Or 4000 times of agricultural streptomycin or strong chlorine extract 2500 times, control efficiency increased significantly. In addition, every 667m2 can also be used 10% chloramphenicol 100g or 70% Ye Shujing (killing net) rubber suspension 100-150g, 25% Ye Ling Ling (渝-7802) WP 175-200g, on the water 50-60L spray. In the 5-leaf stage and 5 days before rice transplanting, each sprayed with 500 times solution of mycinomycin or 1 time with 50% Chlorobromoisocyanuric acid water-soluble powder (Mendril), the amount of 25-50g per 667m2 , Spray 50kg on water.

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