Control of common diseases in rice

1. Rice blast

Rice blast, also known as rice fever, can be divided into seedling blast, leaf blast, ear and neck blast, branch blast, grain blast and so on.

Seedling blast: the base is gray-black, the upper part turns brown, curls and dies, when the humidity is high, the disease produces a large number of gray-black mildew layer, and leaf blast can occur throughout the growth period. The damage from tillering to jointing stage is more serious.

Distemper: Brown dots are produced on the rice node, and then gradually expand around the node, making the diseased part black and easy to break. The formation of withered and white spikes occurs early. It occurs only on one side, causing the stem to bend.

Panicle neck blast: Brown dots are formed at the beginning, which browns the neck of the ear and causes withered and white ears. The late onset causes blighted grain. Spikelets are sterile due to damage to branches or rachis.

Grain blast: produces brown oval or irregular spots, which can blacken the rice. Some glumes are asymptomatic and the glume protection becomes brown, which makes the seeds carry bacteria.

Control methods: select disease-resistant varieties; reasonable fertilization, increase the application of organic fertilizer, phosphorus and potassium fertilizer; scientific drainage and irrigation; 2-3 days before the break, use 40% Fuji 1 EC 75g 100ml or 20% tricyclazole wettable powder 100g / mu mixed with 20g iodine alginate, add water 50g 75kg spray, spray again in 7 days.

2. Rice bacterial blight

Symptoms: mainly occurred in leaves and leaf sheaths. At the beginning, the translucent yellow spot appeared at the leaf edge, and then the wavy yellow-green or grayish-green spot developed along one or both sides of the leaf vein or along the midrib; the dividing line between the disease part and the healthy part was obvious; after a few days, the spot turned gray and curled inward. When the air is moist, wet and turbid water droplets or honey-yellow bacterial gum are secreted on the leaf edge of fresh disease spots, which dry up and form hard particles, which are easy to fall off.

Control methods: select disease-resistant varieties; soak seeds with 50 times solution of 1% Zhongshengmycin for 24 hours to disinfect; cultivate disease-free and strong seedlings; 7-10 days before transplanting, spray with 20% Ye Kuning wettable powder 500 times solution mixed with iodine alginate per mu. After heavy wind and rain, the flooded rice fields should be protected by spraying seedling iodine alginate in time.

3. Rice sheath blight

Symptoms: the leaf sheath produces dark green water-immersed edge blurred spots, and then gradually expands in oval or moire shape. when the disease is serious, several disease spots merge to form large disease spots, showing irregular moire spots, often causing leaves to yellowing and withering to death; when the disease occurs quickly, the disease spot is dark green and the leaf decays quickly. Stem damage often can not heading, under the condition of high temperature, there is a layer of white powdery mildew on the disease spot.

Control methods: waterlogged sclerotia, reduce bacteria source; do not apply nitrogen fertilizer, increase phosphorus and potassium fertilizer; reasonable close planting, reasonable irrigation, shallow water irrigation, moderate drying, reduce field humidity; spray 30% sclerotia net WP 800 × 1000 times solution mixed with race alginate iodine for 3 times before closing to maturity.

4. Rice flax spot

Symptoms: seed bud stage damage, coleoptile browning, bud not pulled out, cotyledons withered. When the leaf and leaf sheath occurred at the seedling stage, the disease spots expanded into strips, and the seedlings withered when the disease spots were frequent. The infected edges of adult leaves are brown, and in severe cases, they form irregular spots. The diseased leaves are dry and damp brown from the tip of the leaves, and black mildew is produced on the dead seedlings. The leaf sheath became diseased and watery, and then turned into a grayish brown irregular spot in the center. The injured part of the neck and branches is dark brown, causing the ear to wither. The grayish black of the infected grain extends to the whole grain to cause blighted grain. When the climate is humid, the disease grows into a black villous mildew layer.

Prevention and control methods: disinfection of improved varieties, increase the ratio of soil to soil, avoid partial application of nitrogen fertilizer; 20% Jinggangmycin wettable powder 1000 times solution mixed with flower and fruit doctor fruit can be sprayed with multi-elements.

5. Rice stripe blight

Symptoms of the disease: in the early stage of rice growth, chlorotic yellow stripes appeared in the heart leaves and the first leaves under the heart leaves, then gradually expanded to irregular long yellow stripes, the heart leaves twisted or withered, forming a "false withered heart", and finally the whole plant died. In the later stage of rice growth, the flag leaf and the flag leaf sheath fade to yellow or yellow-white, and the diseased ear is often wrapped tightly in the leaf sheath and is not easy to pull out, forming a withered booting ear, which makes the rice can not bear fruit normally, which has a great effect on the rice yield.

Control methods: ploughing and planting to reduce the number of gray planthopper overwintering; removal of roadside and gully edge weeds; selection of disease-resistant varieties; application of Defuer drip irrigation and fertilization to avoid partial application of nitrogen fertilizer; seedling stage and early stage of Honda, 50 kg of 1000 times aldicarb per mu, or 2 kg of cicada powder and 2 kg water spray.

6. Rice bacterial leaf streak

Symptoms: mainly for damage to leaves, sometimes to damage leaf sheaths. The disease spot occurs between the leaf veins, which is initially a dark green water stain-like speck. after expansion, it is limited by the leaf vein to form a dark green strip, which is transparent to the light, about 10 mm long and 1 mm wide. the surface of the disease spot often secretes a lot of yellow bacterial pus, showing yellow gum-like particles after dry knot.

Prevention and control methods: improved variety disinfection; 50% Dysenamine 500-600 times solution mixed with flower and fruit doctor fruit can be sprayed with multi-elements, start spraying at heading stage, and apply again after 7 days.

7. Rice evil seedling disease

Symptoms: the disease can occur from seedling stage to heading stage, the color of diseased seedlings is yellowish green, the growth of diseased seedlings is higher and weaker than that of healthy seedlings, the leaves are long and narrow, and the roots are poorly developed.

Characteristics of the disease: the pathogen overwintered on diseased rice straw or the seed itself carried bacteria, which became the source of primary infection. The pathogen was immersed into the base of seedling stem from the wound and spread through irrigation water and Rain Water.

Prevention and control methods: 1. Select non-diseased varieties to avoid leaving seeds in diseased fields and nearby fields; 2. Seed disinfection can be carried out with carbendazim, Quan Baike, strong chlorine, etc., the key is disinfection; 3. If you find a diseased plant, remove it immediately.

8. Rice false smut

Harm to individual grains, the initial formation of mycelium in the grain, gradually increased, so that the inner and outer glumes open, revealing a yellowish mass, that is, the spore seat of the pathogen.

Prevention and control methods: 1. Select disease-resistant varieties; 2. Seed disinfection, same as rice blast and sheath blight; 3. Combined with the control of sheath blight, Jinggangmycin was sprayed for 3 times from closing to maturity for 4 times.

9. Rice leaf sheath rot

Symptoms (1) leaves: leaf sheath rot mostly occurred on the flag leaf sheath of rice at booting stage, the initial symptoms were dark brown spots, the edges were blurred, and the rear spots gathered into cloud-like disease spots, like tiger spots, and the disease spots continued to extend to most of the leaf sheaths.