Rice downy mildew
The symptoms are also called yellowing and atrophy. In the late period of Putian, it began to show symptoms, and the symptoms were obvious during the peak period of childbirth. Occurrence of yellow and white spots on the leaves, followed by the formation of irregular surface stripes, mottled mosaic. The heart of the diseased plant is yellowish, curly and difficult to withdraw. The old leaves of the lower part gradually wither, the roots are stunted, and the plants are dwarfed. The victim leaf sheath is slightly soft, irregularly corrugated or wrinkle-resistant, twisted, and reduced in birth. If all parts of the phlegm are susceptible to disease, serious disease strains can not boot the ear, lightly diseased plants can boot but can not be extracted, wrapped in flag leaf sheath, or arched out from its side into a box-shaped, spike small false, distorted deformity. In the late days of Putian and Honda, the disease became severe.
The pathogen Sclerophthora macrospora (Saccardo) Thirumalachar, Shaw & Narasimhan var. oryzae Zhang & Liu said that the bacterium Bacillus subsp. Occluder spherical, pale yellow-brown, size 65-9564-78 (μm). Males 1-4, lateral, size 45-757.5-10 (μm). The oospore initially became colorless and yellowish-brown, oval in size 51-7551-75 (μm). Sporangium lemon-shaped, colorless, solitary at the apex of cysts, single stems of cysts extending from stomata, branching on them, multiple spores contained in sporangia, oval spores, double flagella , It is spherical after rest. (right)
Transmission routes and conditions The bacteria can infect 43 genera of Gramineae. disease
Bacteria spore with spores overwinter in the soil. Infested oocysts infested weeds or rice seedlings. The oospores are transmitted by the water stream, and the spores and zoospores are produced by the oospores under flooding conditions, and mycelia invades the rice soon after the zoospores are stopped. The oospore germinates at 10-26°C, 19-20°C. 10-25 °C can cause disease, 15-20 °C optimum. Alfalfa seedling stage is the main disease-susceptible period of rice, and field plants are mostly introduced from Putian. Flooding, heavy rain or continuous cloudy rain in Putian has a severe onset, and low temperatures are conducive to disease.
Prevention and control methods (1) Choose a land plot with a high topography to do a paddy field and build a drainage ditch. (2) Remove pathogens, remove weeds and diseased seedlings. (3) In the early stage of drug control, spray 25% metalaxyl WP 800-1000 times or 90% Elimination Net WP 400 times, 80% WP WP 700 times, 64% antivirus Wet powder 600 times liquid, 58% metalaxyl manganese zinc or 70% zinc phosphorus manganese zinc WP 600 times, 72.2% Promefone (Pric) 800 times liquid.
Ultrasonic Nebulizer,Handheld Nebulizer,Mesh Nebulizer,Portable Nebulizer Machine
Shenzhen urion Technology Co., Ltd. , https://www.urionhealth.com