Occurrence and Control of main Rice Diseases and pests in Gejiu City

Rice planthopper

1. Damage characteristics: Rice planthopper, also known as white mosquito, is a migratory pest with the characteristics of long-distance migration and outbreak. The common ones are gray planthopper and white-backed planthopper. It occurs in the rice areas of the city, mainly harming rice, followed by @ # @ 245 grass and corn, which are also parasitic on grass and other Gramineae weeds. The adults and nymphs clustered to suck the sap on the base and leaves of the rice clump, and the injured part showed a long brown spot. In severe cases, the lower stem blackened and the whole plant withered.

2. Living habits: there are 4 generations in a year, and from the end of April to the beginning of May, they move into early and middle rice fields from other places. Generally speaking, from June to July, the density of insect population in the field is high, and the short-wing type increases, so the damage is more serious. The early and middle rice migrated to the late rice field and weeds after harvest, and the damage of late rice was lighter. The phototaxis of adults are not strong, and eggs like to be laid on paspalum grass in paddy fields.

3. Control countermeasures: (1) do a good job in propaganda and mobilize the masses: due to the many peaks of rice planthopper migration, the extremely irregular progress of field development, and the difficulty of controlling the appropriate period of control, all localities should do a good job of rice planthopper monitoring at the same time, it is necessary to make full use of broadcasting, blackboard newspapers and other publicity forms to release timely information on the occurrence of rice planthopper to the masses, especially to vigorously publicize the seriousness and control techniques of rice planthopper, in the critical period of control. Go deep into the village community, do a good job in propaganda, mobilization, organization and guidance, actively carry out unified control of rice planthopper, and strive to reduce the damage and loss of rice planthopper to a minimum. (2) Pesticide control: the medicament is selected according to the principle of combination of quick effect and long effect, combination of contact and internal suction, combination of egg killing and insecticidal. 75 grams of insecticide per mu plus 30 grams of planthopper net and 50 kg of water spray; or 25% of buprofezin wettable powder 50 grams of water and 60 kg of water spray; or 10% of imidacloprid EC 40ml 60 kg of water 40 kg per mu of spray. (3) Note: with the rainfall, rice planthopper will break out suddenly, so the early pest is not serious, must not be taken lightly, should be checked at any time, prevention.

Rice borer

1. Damage characteristics: Rice stem borer, Chilo suppressalis and Chilo suppressalis, not only damage rice, but also damage corn, millet, sugarcane, Zizania caduciflora, broad bean and rape and other crops, but also parasitic on gramineous weeds. The larvae do harm to rice, resulting in withered seedlings, withered sheaths, semi-withered ears, white ears, dead booting or pest-damaged plants.

2. Life habits: take Chilo suppressalis as an example, three generations a year, with larvae overwintering in rice stubble. Pupation and Eclosion in spring. Moths are active at night and have phototaxis. Most of the eggs were laid near the leaf tip in the seedling stage and in the middle and upper part of the leaf in the field stage. After the eggs hatch, the ant borer causes stem decay on nearby plants, resulting in "withered heart clumps" or "white ear clusters". Larvae can transfer damage. When harming the booting rice, first bite the tender grains at the panicle bud, and then eat the upper stem nodes after heading to cause white panicles. Rice is the most vulnerable at tillering stage and booting stage, and it is not easy for ant borer to invade at round culm stage or after full heading.

3. Control methods: (1) eradicate rice stubble and field edge weeds and eliminate overwintering larvae; timely spring ploughing and irrigation for 7 days to kill larvae and pupae; prevent variety mixing and timely planting, so as to avoid the peak period of ant borer in the vulnerable period to reduce the damage. (2) the control should be carried out according to the control time predicted by the plant protection station during the peak period of the moth and when the ant borer is fully hatched. The medicament can be selected as follows: 40ml 50g / mu of insecticidal wettable powder with 50kg water spray; or 200mu / mu insecticidal double water agent 200mer 250g / mu sprayed with 50kg water; or 50-60ml / mu with 50kg water spray; or 98% Batan powder 50g / mu with 50kg water spray.

III. Rice blast

1. Damage symptoms: Rice blast, also known as rice fever, is a fungal disease caused by Magnaporthe grisea. Rice can occur in all growth stages and parts, which can be divided into seedling blast, leaf blast, node blast, panicle neck blast, branch blast, grain blast and so on according to the occurrence period and location. The main results are as follows: (1) Seedling plague: it mostly occurs in 2mi 3-leaf stage, which is caused by seed carrying bacteria. The pathogen invades the base of seedling and appears gray and black, resulting in seedling curling and death, and generally does not form obvious disease spots. (2) Leaf blast can occur from the third leaf stage to the panicle stage, and it is easy to occur in the fields with late topdressing, partial application of nitrogen fertilizer and thick green leaf color at the full tillering stage. There are four types of leaf blast disease spot, namely ① chronic type: the most common symptom on the leaf, the disease spot is fusiform, the peripheral toxic part is yellow halo, the edge necrotic part is reddish brown, the central collapse part is gray-white. ② acute type: the disease spot is dark green, most of it is nearly round or irregular, the center of the spot is gray-green, the outer edge of the spot is flooded, and the back produces gray green villous mildew layer. ③ white spot type: the disease spot is nearly round spot; ④ brown spot type: the disease spot is brown spot. (3) panicle neck blast: it occurs on the ear neck, and the disease spot spreads up and down, showing light brown or grayish black. At the initial stage, the disease spot shows a light brown water stain, and gradually spreads and develops upward and downward around the ear neck, ear axis and branches. After that, the color becomes dark brown or dark green, blackens, dies or breaks, seriously affecting fruiting, grain weight and rice quality. Most of them occurred in 2Mel 3-leaf stage, which was caused by seed-borne bacteria, which invaded the base of seedlings and appeared gray-black, resulting in seedling curling and death, and generally did not form obvious disease spots. (2) Leaf blast can occur from the third leaf stage to the panicle stage, and it is easy to occur in the fields with late topdressing, partial application of nitrogen fertilizer and thick green leaf color at the full tillering stage. There are four types of leaf blast disease spot, namely ① chronic type: the most common symptom on the leaf, the disease spot is fusiform, the peripheral toxic part is yellow halo, the edge necrotic part is reddish brown, the central collapse part is gray-white. ② acute type: the disease spot is dark green, most of it is nearly round or irregular, the center of the spot is gray-green, the outer edge of the spot is flooded, and the back produces gray green villous mildew layer. ③ white spot type: the disease spot is nearly round spot; ④ brown spot type: the disease spot is brown spot. (3) panicle neck blast: it occurs on the ear neck, and the disease spot spreads up and down, showing light brown or grayish black. At the initial stage, the disease spot shows a light brown water stain, and gradually spreads and develops upward and downward around the ear neck, ear axis and branches. After that, the color becomes dark brown or dark green, blackens, dies or breaks, seriously affecting fruiting, grain weight and rice quality.

2. The law of disease: the conidia and mycelium overwintered on rice straw and rice seeds, and were transmitted by air. At tillering stage and early booting stage, the epidemic of leaf blast was easily caused by the temperature of 20 ℃ and high humidity, and the low temperature of about 20 ℃ after booting could weaken the disease resistance of the host and cause the epidemic of panicle neck blast. In the suitable temperature range, rainy and humid is the main condition for the epidemic of the disease. Excessive growth caused by partial application of nitrogen fertilizer, soil drought and lack of water or long-term deep irrigation, cold water irrigation or lack of sunshine are easy to cause rice blast.

3. Control methods: the comprehensive control measures of rice blast should be centered on planting resistant and high quality varieties, based on health cultivation and assisted by chemical protection. The main results are as follows: (1) planting disease-resistant varieties is the fundamental measure to control rice blast, so all localities should select disease-resistant varieties according to local conditions, and achieve rational distribution and rotation of varieties so as to avoid single planting. (2) seed treatment: the rice seeds can be disinfected with strong chlorine. The rice seeds can be pre-soaked for 24 hours, then disinfected in 300 Mel 400 times chlorine solution for 12 hours, removed and washed, and then germinated, which can also treat fine streak disease and bacterial leaf blight; or soak the seeds with 2000 times solution of 75% tricyclazole wettable powder for 2436 hours, wash and accelerate germination. (3) strengthen cultivation management: cultivate strong seedlings, apply sufficient base fertilizer, increase organic fertilizer and potassium fertilizer, supplement silicon fertilizer, skillfully apply ear fertilizer, frequently irrigate in shallow water, sun the field timely, prevent partial application and late application of nitrogen fertilizer. (4) Pesticide control: in the control strategy, the methods of "controlling seedling blast, picking and controlling leaf blast and ear blast" should be adopted. Control seedling blast in rice seedlings 3 days before transplanting with 75% tricyclazole wettable powder 2000 times liquid spray, so that rice seedlings transplant with medicine, the control effect is better; leaf blast should be protected at the initial stage (when the rate of diseased leaves is 3%); panicle and neck blast is the most effective in late booting and belly breaking stage. Medicament selection: 75% tricyclazole wettable powder 30ml 35g per mu, or the fundamental measure to control rice blast, so all localities should select disease-resistant varieties according to local conditions, and achieve rational distribution and rotation of varieties to avoid single planting. (2) seed treatment: the rice seeds can be disinfected with strong chlorine. The rice seeds can be pre-soaked for 24 hours, then disinfected in 300 Mel 400 times chlorine solution for 12 hours, removed and washed, and then germinated, which can also treat fine streak disease and bacterial leaf blight; or soak the seeds with 2000 times solution of 75% tricyclazole wettable powder for 2436 hours, wash and accelerate germination. (3) strengthen cultivation management: cultivate strong seedlings, apply sufficient base fertilizer, increase organic fertilizer and potassium fertilizer, supplement silicon fertilizer, skillfully apply ear fertilizer, frequently irrigate in shallow water, sun the field timely, prevent partial application and late application of nitrogen fertilizer. (4) Pesticide control: in the control strategy, the methods of "controlling seedling blast, picking and controlling leaf blast and ear blast" should be adopted. Control seedling blast in rice seedlings 3 days before transplanting with 75% tricyclazole wettable powder 2000 times liquid spray, so that rice seedlings transplant with medicine, the control effect is better; leaf blast should be protected at the initial stage (when the rate of diseased leaves is 3%); panicle and neck blast is the most effective in late booting and belly breaking stage. Medicament selection: 75% tricyclazole wettable powder 30ml 35g per mu, or 55.5% mu smash 100g tricyclazole, or 20g tricyclazole 150g per mu, or 40g distemper dispersible EC 150ml 200g mixed with water 6075kg uniform foliar spray. If there is cloudy and rainy weather or low temperature in the later stage, the medicine must be sprayed again in full ear, but it is not suitable to blindly increase the dosage, and several pesticides can be used alternately.