Rice disease

1. Rice blast

(1) damage characteristics: Rice blast, also known as rice fever, commonly known as fire blast, hanging head blast, neck-choking blast and so on, is one of the most widespread and harmful fungal diseases in the world, which mainly harms the aboveground part of the host plant. Due to the different damage period and position, it can be divided into seedling blast, leaf blast, ear neck blast, branch blast, grain blast and so on. The host range is many kinds of Gramineae plants, such as rice, @ # @ 245 grass, horse tang and so on. Magnaporthe grisea overwintered mainly on diseased rice straw and was infected in rice field in the second year. Germs spread mainly by wind, and rain, water and insects can also spread. When the weather turns warm and there is rain, the overwintering pathogen will recover and proliferate, transferring from the diseased straw piled on the edge of the field to the rice plant.

(2) Control methods: ① selected improved varieties, planted disease-resistant varieties, and multiple combinations were reasonably matched. ② seeds were disinfected and sterilized. 1 kg seeds were soaked with 3 grams of 20% tricyclazole for 24 hours. ③ strengthens cultivation management. Soak the seedlings with ④ solution, soak the seedlings with 20% tricyclazole wettable powder 750x solution, or 40% rice disinfectant EC, spray Huan 60kg with 100ml or Fuji No.1 EC per mu. For the prevention of neck blast, 75% Fengdeng wettable powder was used in the booting stage, 250g / mu or 20% tricyclazole 100g / mu, leaf blast was treated, and rice blast pesticides were used to control it.

2. Bacterial blight

(1) damage characteristics: Rice bacterial blight is also called burning seedlings. White leaf disease is a fast-spreading disease. at present, there is no this disease in many rice areas, so it has been designated as the object of plant quarantine in China.

After the rice plant was infected with bacterial blight, green or dark green spots appeared at the leaf tip or leaf edge, and the disease spot expanded along the midrib or leaf edge, forming a well-defined disease spot. The disease spot is grayish white along the leaves after death, so it is called bacterial blight. Generally speaking, the disease occurs first in the middle and lower leaves of rice, and then spreads to the upper leaves. The disease occurs at the seedling stage, develops generally at the tillering stage, and reaches the peak at the booting stage, especially after heading. If the disease occurs early, the leaves die and cannot heading; if the disease occurs later, the flowering is affected, the blighted grains increase, and the stem of the diseased plant is weak and easy to lodge.

Bacterial blight is easily confused with other diseases and can not be identified clearly. You can cut off a small section of the diseased leaf, put it on a piece of glass with water, and then press it on it with a small piece of glass. About 1 minute later, put it in a place with dim light. If there is a thick or milky liquid flowing out of the cut, this is the pathogen of bacterial blight.

(2) Control methods: strict quarantine of ① and selection of disease-free rice varieties. The seeds can be filtered and soaked with 1% lime water. When the temperature is 25 ℃, the seeds can be soaked for 3-4 days. The soaked rice seeds are often kept 10-12% below the water surface, the water surface can not be stirred, so as not to break the lime water film and reduce the disinfection effect. ② selected varieties resistant to bacterial blight. ③ tillering fertilizer and panicle fertilizer should not be too much. Frequent irrigation in shallow water and timely roasting of the field can promote the healthy growth of rice and improve the ability of disease resistance.

3. Sheath blight

(1) damage characteristics: sheath blight, also known as moire disease, commonly known as eyebrow spot, flower foot blast and mildew green stalk, is one of the important diseases of rice.

The disease began to occur at the tillering stage and became more and more serious in the later stage. it mainly damaged the leaf sheath and leaves near the water surface, and in severe cases, it also damaged the upper leaf sheath and leaves. The lesion was oval at the beginning, grayish green in the center of the leaf, and then expanded into irregular striated spots. After the enlargement of the disease spot, the leaf sheath and leaves withered and the tillers died. in severe cases, the rice plant could not heading or could not bear fruit, or caused early lodging, and the light disease increased the empty grain and decreased the grain weight.

(2) Control methods: ① to strengthen cultivation management. Irrigation in shallow water, timely roasting, seedling watching and fertilization can promote the health of rice, improve the ability of disease resistance, reduce the humidity of rice field, ventilate and penetrate light, and inhibit the growth and transmission of bacteria, so as to effectively control the occurrence of diseases. ② eliminated sclerotia, combined with deep turning and burying sclerotia in autumn and winter. Irrigate the whole field and fish out the scum with a large amount of sclerotia before transplanting seedlings. ③ efficacy control, (A) 1500 times liquid spray can be prepared with 50% anti-bacterial wettable powder per mu or sprinkled with 150g water 500kg 1000kg; it can also be sprinkled with 150g 200g fine soil 20kg. (B) use 500g Jinggangmycin per mu plus 50kg water, spray or irrigate. When applying the pesticide, the rice field should be irrigated with a water layer of 2 to 3 centimeters deep.