Bacterial blight of rice is a major bacterial disease that has occurred in rice in recent years. The disease has a high prevalence rate, heavy damage, and difficulty in control.
First, the symptoms of damage
Leaves and leaf sheaths. At the beginning of the season, small translucent yellow spots appear on the margins of the leaves, and then along the leaf margins on one or both sides or along the midrib, develop a corrugated yellow-green or gray-green lesion; the boundary between diseased and healthy parts is obvious; the lesion turns several days later. It is gray and curled inwards, looking a bit hazy. When the air is humid, fresh lesions on diseased leaves, and sometimes even on the leaf margins that do not show signs of disease, secrete wet, turbid water droplets or honey-yellow bacteria, and when dried, they form into hard particles and are easily detached. Bacterial blight in japonica rice occurs mainly from grayish green to grayish white, and yellowish green or yellowish greenish blight on japonica rice. In the susceptible varieties, the lesions in the early stages showed gray-green burnt with hot water and quickly developed into long, yellow-white.
Second, the law of transmission and incidence
Xanthomonas oryzae mainly overwinters rice seed, straw and rice piles. Sowing of diseased valleys, germs can invade through the roots and the coleoptiles of the seedlings. The pathogenic bacteria on the rice straw and rice piles seep into the water stream when they encounter rainwater. The seedlings are exposed to the carrier water, and the bacteria invade into the rice body from the water hole and wound. Straw germination with diseased rice, covering seedlings, barbs, and other favorable diseases spread. Early and mid-season paddy field due to the low temperature, bacteria less, generally do not see the symptoms, until the boot before and after the burst out. The pus on the lesion can be re-infested by wind, rain, dew, and leaf contact. The disease is most suitable for the popular temperature of 26-30 °C, below 20 °C or 33 °C above the disease development. Rainwater is abundant, humidity is high, especially heavy rainstorms cause a lot of wounds in rice leaves and provide extremely favorable conditions for the spread of bacteria; seedlings flooding; paddy field deep irrigation, string irrigation, flood irrigation, application of excessive nitrogen fertilizer, etc. are favorable to disease; breed resistance Significant differences, large-scale planting of susceptible varieties, favorable disease prevalence.
Third, control methods
Putian must plant disease-resistant varieties. 1. Selection of Disease Resistant Varieties: Fields with Bacterial Leaf Blight
Strong chlorine soaking or 80% "402" soaking. 2, seed disinfection: with
Ye Kuning or Ye Qingshuang Wettable Powder 3. Cultivate disease-free and strong Zhuang: Choose the position of Putian, strengthen irrigation water management and prevent flooded seedlings. Precaution is applied during the clover period and before transplanting. Mu with 25% 100 g watered spray.
4. Strengthen water and fertilizer management: Level up paddy fields to prevent string-irrigation and flooding to spread disease; timely and moderately dry fields, apply sufficient base fertilizer, and apply P and K fertilizers more frequently. Do not apply excess nitrogen fertilizer too late.
5. Field application protection: After rice is jointed, the susceptible varieties should be checked as soon as possible. If the disease center is found, it should be treated immediately; the susceptible rice field should be applied after a heavy rainstorm. Candidates such as chlorfluazuron, phytosclerin, herbicides, and bacterin are used. Various fungicides can be used interchangeably to prolong the life of pesticides. The application of pesticides should be carried out after the dew has dried in order to avoid transmission of diseases due to handling.
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