In the treatment of brown planthopper , it is necessary to use the drug according to the occurrence and damage characteristics of brown planthopper, and select appropriate insecticide according to the occurrence of brown planthopper in the field. The occurrence and damage characteristics of brown planthopper The brown planthopper is a migratory pest. It cannot surpass the winter in the north of 25° north latitude. The annual insect source is transferred from generation to generation and zone by season. In the Yangtze River Basin and its north, brown planthoppers generally move in after mid-July, usually forming a peak in the typhoon and other airflow from south to north. The number of adults who move in each time is generally not particularly large, which is not enough to cause great harm to rice in the field immediately. Usually it is propagated in the field for one or two generations, and the amount of insects will increase enough to cause damage to rice. The brown planthopper has a long life span, a long spawning period, and a large amount of eggs. At a temperature of 26 to 28 ° C, the adult life of the brown planthopper is 15 to 25 days (the life span is 30 days at 17 to 20 ° C). Female adults have strong fertility, 150 to 500 eggs per head, and many (especially short-winged adults) can reach 700 to 1000; the spawning period lasts 10 to 15 days, and the peak of spawning usually lasts 6 to 10 days. The time required for embryonic development of brown planthopper eggs is closely related to the temperature. The egg lengths at 2°C, 20°C, 25°C, 28°C and 29°C are 26.7, 15.2, 8.2, 7.9 and 8.5 days respectively at 28°C. The left and right egg period is the shortest, and the hatching rate is the highest at a temperature of about 25 °C. Brown planthopper harms rice and can be divided into direct damage and indirect damage. The direct hazard is direct consumption of rice sap, consuming rice nutrients and causing harm. Brown planthopper adults, nymphs can suck juice harm rice. Indirect harm is brown planthopper adults, nymphs sucking sap and the leaf sheath and Blade punctured when females lay eggs with the ovipositor, dehydration and easy to make rice plants infected with Sclerotinia, its excrement breeding ground for mold, but also affect photosynthesis in rice And breathing. Brown planthopper control strategies Rice brown planthopper ability have strong resistance to damage, the field has occurred when a small amount of brown planthopper, rice growth are not affected, generally do not need medication control. But in the brown planthopper outbreak of the year, if the growth of the rice brown planthopper moved before the mid-volume, you should try medication to control pest field, reduce pest base. In the pre-pregnancy use of rice, the prevention and treatment indicators are generally 500 heads per 100 points, that is, there are about 5 points in a hole. In the middle and late stages of rice growth, the control index of brown planthopper is generally 1000 heads per 100 points, that is, about 10 heads per hole. Not far away from the strong harvest rice stalks and other organizations, aging resistance, the brown planthopper ability, control indicators can be raised. The use of drugs to control brown planthoppers is generally required to be used at the peak of nymph hatching. At this time, the use of drugs, the concentration of pests, and the sensitivity of the drug, that is, the use of short-lived drugs such as dichlorvos, chlorpyrifos, can also kill a large number of brown planthoppers in the field, so that the number of groups is reduced to the extent of harm. Treatment of brown planthopper At present, the insecticides suitable for controlling rice brown planthopper are mainly organophosphorus pesticides such as dichlorvos and chlorpyrifos, carbamate pesticides such as isoprocarb, zhongdingwei and butyl thiocarb, as well as buprofezin and pymetrozine. Pesticides such as chlorothiazide and thiamethoxam. Different kinds of pesticides have their insecticidal characteristics, and reasonable use can achieve good control effects and save labor. It makes sense to have a trial. According to the plant protection research institute of Jinhua City Academy of Agricultural Sciences, Zhejiang Province, using 25% buprofezin WP to control brown planthopper, 25 grams, 35 grams, 50 grams per acre, 60 kg of water, 80% dichlorvos per acre 200 ml of emulsifiable concentrate and blank were used as control. The field was filled with water 3 cm deep before application. After the water was naturally dried, the water was sprayed. The average control effect after 7 days of application was 97%, 97%, 98.7%, and 88.5%, respectively. After 14 days, the control effects were 99.1%, 99.6%, 99.8%, and 18.2%, respectively; the control effects at 28 days after application were 98.1%, 98.4%, 99.3%, and -15%, respectively. Twenty-eight days after application, nearly two-thirds of the plants in the blank control area were harmed by brown planthoppers, and the rice treated by Ule was kept green and yellow. Through this test, it was confirmed that the use of buprofezin to control brown planthopper has a long-lasting effect and good effect, and the researchers found during the test that the use of dichlorvos to control brown planthopper, short-lived period, will kill spiders and black shoulders and green blinds. The natural enemies such as è¤ è¤ ä½¿ , , , , , , , , , , , , , è¤ è¤ è¤ è¤ è¤ è¤ è¤ è¤ è¤ è¤ è¤ è¤ è¤ è¤ è¤ è¤ è¤ è¤ è¤ è¤ è¤ è¤ è¤ è¤ è¤ The advantages of long-acting drugs Adult brown locusts and nymphs are clustered near the base of the rice plexus for feeding, and generally do not move much. In the middle and late stages of rice growth, the rice in the field grows densely, and it is difficult to deliver the drug to the base of the rice plant by spray application. The drug with strong systemicity such as buprofezin can be absorbed by the stems and leaves of rice after being sprayed, and then transferred to the feeding site of the brown planthopper to kill the pest. According to a report by Dai Zhiyi et al., "The internal absorption and digestion dynamics of buprofezin on rice", rice has a strong systemic effect on buprofezin. After spraying buprofezin, rice leaves It can absorb drugs and transport them to the base of rice to kill brown planthoppers that are harmful to the base of rice. Rice sheaths and stems can absorb and enrich the buprofezin in field water with a concentration factor of 24-35. The application of the crude spraying, pouring, misting, toxic soil (with water layer) and other different application methods, the difference in the control effect of brown planthopper is not significant. Buprofezin has a strong contact effect on brown planthopper, and it is applied by spraying and mist. The pest mortality is relatively high in the short term after application. In addition, in the case of a water layer in the field, the sheath and stem of the rice plant can absorb the chemicals that fall on the field when applied, and the application of the water layer in the field is better after the application of the method. Therefore, paddy fields should maintain an appropriate water layer during the application period to increase the field control effect and prolong the efficacy period of buprofezin. Long-acting drug for the treatment of brown planthopper It is understood that currently applicable to the control of brown planthopper, the system has a systemic, long-lasting agent, in addition to buprofezin, but also pymetrozine, chlorothiazide, thiamethoxam, butyl thiocarbacarb Wait. These agents have their own characteristics and can be flexibly selected for production. Uazizinone, also known as Youle De, Phloem, Dao Ling, and Daojing, is a bactericidal insecticide with strong contact and stomach toxicity. The mechanism of action is to inhibit the synthesis of chitin and interfere with the metabolism of the insects, causing the nymphs to die or deform their wings and slowly die. Generally, the effect can be seen 3 to 7 days after the application. It has no direct lethal effect on adults, but it can shorten its life span, reduce the amount of eggs laid, and produce more sterile eggs. The larvae die quickly even if they hatch. It has good control effect on the insects of spider mites, spider mites, whitefly and scale insects, and the efficacy period is more than 30 days. It is safer for natural enemies and has a good overall effect. The drug has been used in production for many years and has been resistant to brown planthopper. Pyridoxine, also known as pyrazinone, has a contact-killing effect on pests and also has systemic activity. It can be transported in the xylem and phloem in plants. It is suitable for the prevention and control of most of the homopteran pests, especially the mites, whiteflies, spider mites and locusts. 25% pymetrozine wettable powder is used to control rice planthopper, and the recommended dosage per acre is 16-20 grams. Chloromorph is a new type of nicotinic insecticide with contact, stomach and systemic effects. It is broad-spectrum, high-efficiency, low-toxic, low-residue. Pests are not resistant to resistance and are safe for humans, animals, plants and natural enemies. . 25% thiamethoxam water-dispersible granules are second-generation nicotinic insecticides, and their mechanism of action is similar to that of first-generation nicotinic insecticides such as imidacloprid, but with higher activity. It has stomach poisoning, contact killing and systemic action, and it has a fast action and a long-lasting effect. It has good control effect on sucking pests such as aphids, planthoppers, spider mites and whiteflies. Butyl thiocarbamate has a contact and stomach toxic effect on insects (the insecticide is metabolized to a toxic carbofuran), which is systemic, has a long-lasting effect, and has a wide spectrum of insecticides. At present, the medicines registered for the control of rice planthoppers have gold good years and so on. Although the above-mentioned medicaments are systemic, in the middle and late stages of rice growth, when used to control brown planthopper, the amount of water should be increased. Generally, the water spray per mu of the manual sprayer should reach 50-60 kilograms, and the water consumption per acre by the mister is sprayed. Should reach 40 kg. In this way, the drug solution can be sprayed on the base of the rice plant to exert its contact action, and at the same time, it is beneficial for the rice to absorb the drug and exert the drug effect. The field should generally be kept in the field for 2 to 3 days after application. The imidacloprid widely used in production in previous years also has the functions of systemic absorption, contact killing and stomach toxicity. It was once a nemesis of rice planthopper, but due to years of abuse, insects such as brown planthopper and Laodelphax striatellus have had strong resistance to it. Sex, the control effect is significantly reduced, especially the brown planthopper, the resistance of the drug is very strong, it should not be used to control brown planthopper. Although organophosphorus pesticides such as omethoate and acephate have strong systemic properties, chlorpyrifos also has certain systemic properties, but these insecticides have relatively low insecticidal activity, and brown planthopper has strong resistance to them. The lower amount of the agent in the plant is not sufficient to kill the brown planthopper. Production mainly uses the contact and fumigation effects of chlorpyrifos and other agents to kill brown planthopper. Quick-acting short-acting drugs can be used as appropriate Dichlorvos, chlorpyrifos, dipyridamole, zhongdingwei and other agents have good killing ability to brown planthoppers. After application, the brown planthoppers and nymphs in the field will die a lot, but these drugs have a short duration, only one to two days long. It is only about 7 days, and there is no continuous control effect on the nymphs hatched after the efficacy period and the newly moved adults. The use of these agents alone in production often requires multiple application of drugs, a large amount of work, and high cost of control. The long-acting systemic drug such as buprofezin is used at the peak of the young nymph of the brown planthopper or slightly earlier, and the control effect is high. However, in the field, the density of brown locusts is large, especially when the nymphs and adults are large enough to cause damage to rice. The insecticides are slow, especially the drugs such as buprofezin directly kill the nymphs and adults of the brown planthopper. The effect is poor, and it is necessary to use a quick-killing agent to obtain a fast, good insecticidal effect and a production-preserving effect. For rice with a short harvest time, considering the problem of pesticide residues, it is advisable to release the field water when the temperature is high, and use the dichlorvos with good fumigation effect and short residual period to spread the poisonous soil and smoke the pests.
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