1. Citrus red spider and citrus rust tick are the main pests of citrus in Guangdong Province, which can occur all year round. Because of the many generations of harmful diseases, the long-term damage period, the use of acaricides used to control pests accounts for about 60% to 70% of the cost of pesticides for citrus pest control. How to use acaricide rationally is an important issue related to economic, safe and effective control of citrus damage and ensuring high quality and high yield of citrus. In citrus production, the use of acaricides is often caused by improper use of acaricides, and it affects the normal growth of citrus, the decline of fruit quality, the increase of cost, and even the reduction or loss of production. At the same time, shortly after the new acaricide was put into use, the dosage of the drug was greatly reduced. The reason was often the induction of drug resistance due to improper use. Different kinds of acaricides have different physical and chemical properties, insecticidal effects, safety properties and methods of use. In order to better use the acaricide rationally, improve its effect and economic benefits in the prevention and control of citrus mites, and prolong the service life of acaricides, it is a preliminary discussion on how to use acaricides rationally in the prevention and control of citrus mites. .
1 According to the control object, the suitable acaricide citrus mites are selected, mainly citrus red spider and citrus rust tick. Although they belong to the same genus, they have the characteristics of growth and decline, the damage characteristics and the prevention methods. the same. Therefore, in the prevention and control of mites, the use of the same acaricide often results in different control effects. For example, Nissula has good control effect on citrus red spider, but it is basically ineffective against citrus rust tick; bromo oxime ester has high control effect on citrus rust tick, while citrus red spider has unsatisfactory efficacy. Therefore, it is necessary to select suitable acaricides according to the target of citrus pest control, the law of growth and decline, and the characteristics of damage. Before the application of the drug, an orchard survey should be conducted to confirm which of the most harmful diseases occurred during the period. For example, in the period of citrus red spider, nicotinol, tolk, amitraz, arsenic, acetophenone and other acaricides may be used. For the occurrence of citrus rust tick, bromo oxime ester, polysulfide suspension, stone sulphur mixture, etc. are used. If both red spider and rust tick occur at the same time, then the acaricide, which is ideal for both pest control, such as triazole tin suspension, ketone, etc., can also be used. For example, if a suspension of nisolron plus polysulfide is used, or a mixture of nisolron plus bromo oxime or dimethenone plus polysulfide. Chemical control must be carried out according to the light, heavy, slow and urgent use of the two kinds of pests. That is, depending on which kind of pests occur at the time, the growth rate is fast, the damage is high, and it is urgent to control it, the corresponding killing should be chosen. The agent is mainly used, and the other type of acaricide is supplemented, or two kinds of acaricides that can cure both diseases.
2 According to the different growth stages of citrus, the use of acaricides in different growth stages of citrus must use different acaricides, mainly because the citrus is different in sensitivity to acaricides at different growth stages, that is, the acaricides are different in citrus. Safety issues during the reproductive period. In the practice of many years, it has been found that some acaricides will have obvious symptoms of phytotoxicity when used in the tender shoots and tender fruits. For example, triazolyl tin (powder or suspension) is used in the spring shoots (low temperature) at normal concentrations, causing severe flowering, defoliation, and fruit drop. The fruit and fruit are still deformed during the young fruit period (temperature below 20 °C). In recent years, the phenomenon of serious phytotoxicity caused by misuse of triazolyl suspending agents has occurred from time to time. In addition, the use of Ketite in the citrus shoots, tender fruit period will cause water-stained spots, as well as high concentrations of polysulfide suspensions, such as high-temperature application will cause sunburn is also a common phenomenon. Therefore, in the sensitive period of citrus growth, such as the new shoot period, flowering period or at the same time in the low temperature, high temperature stage, we must carefully choose safe acaricide and safe use concentration in order to receive good control effect.
3 Different acaricides according to meteorological factors Different acaricides have different physical and chemical properties, which determine that they have different pharmacological effects under different meteorological factors. In the production practice, we found that Nissolon acaricide is used in summer, its efficacy is not ideal, and the duration of its effect is short; while in the autumn, the drug is highly effective and has a long-lasting effect. The reason is that there are many rainy days in the south and heavy rainfall in the south. Nissolang EC is slow in drug efficacy, and its adhesion is not strong, and it is not resistant to rain erosion. Therefore, its efficacy is significantly reduced in summer, and the general effect period is below 20 days. The drug is used in autumn and winter. Due to the lack of rain, the efficacy of Nissolang can be fully exerted, and the effective period can reach 30-40 days. After many years of experimental observation, in the summer, Kruth, triazolium tin suspending agent and other acaricides with quick-acting and strong adhesion are used. The control of mites can improve the efficacy and reduce the damage caused by mites. Most acaricides are used at different temperatures and their effects are significantly different. Under low temperature conditions (generally below 20 ° C), many acaricides are not ideal, such as Tork, 螨代治, Kruth, amitraz, etc., but some acaricides are used under low temperature conditions. There is no obvious effect on its efficacy, such as Nissolang, Bazhiling, tacrolimus, triazolyl, etc.; and the use of individual acaricides in the low temperature period is more suitable than in the high temperature period. If the use of chlorpyrifos to control cockroaches, the use period in the high temperature period is short, while the winter use shows its quick effect and long duration. Before the introduction of Ba 螨 Ling and tachyphylline, we have promoted the use of chlorhexidine polysulfide suspension as a medicinal agent for winter citrus clearing. When the temperature is low and the amount of sputum is large, it can still be quickly extinguished. Control the effect of harm. In recent years, citrus orchards have been used in the low temperature period to control cockroaches. Generally, triazole azole suspensions, cockroaches, acesulfame and other acaricides are used. In addition, as mentioned above, different acaricides are used during low temperature or high temperature periods, and citrus is in a sensitive growth period, which may cause different degrees of phytotoxicity. Therefore, when using acaricides, it is necessary to consider the meteorological factors.
4 According to the characteristics of pesticide resistance to cockroaches, if the use of acaricide is unreasonable, cockroaches will have different degrees of resistance to most acaricides. From the introduction of acaricides in Foshan, some acaricides When only 1 to 2a is used, its efficacy is greatly reduced. The introduction of many years of acaricides such as Nisolang, Tolk, and Amitraz, etc., have been decreasing year by year in production, and the introduction of later tyrants and scorpion ketones has also produced serious resistance in many places. Sexual phenomenon. Citrus mites are resistant to certain acaricides, which not only lead to poor control, resulting in loss of citrus production, but also affect some good performance acaricides in the short term. For example, the two kinds of acaricides have a quick effect, a long-lasting effect, and a good quick-acting effect in the low-temperature period, and the use of new shoots and tender fruits during the low-temperature period. In the existing acaricides, there are few acaricides having such advantages. Such as the occurrence of cockroaches in the spring shoots (this is a common phenomenon), these two drugs are currently the preferred target, most other drugs are not unsatisfactory efficacy or phytotoxicity. However, according to the resistance test in recent years, many places of citrus mites have caused serious resistance to arsenic and acetophenone, and the use concentration has increased significantly.
The use of drugs in alternate use is a very effective way to solve the problem of resistance. In the production practice, we use the characteristics of arbutin and acetophenone for the safety of fruit trees and good efficacy at low temperature. These drugs are mainly used in spring (before and after flowering), while in summer and winter, crochet is used. Triazolium tin suspending agent, etc., generally should not be used continuously for more than 2 times per clock. After years of practice, as long as the rational use of more than three kinds of acaricides is adhered to, the occurrence of resistance can be avoided or significantly delayed. The station has a planting area of ​​more than 40 hm2 in the Pingxi fruit field in the South China Sea for 8 consecutive years, using abalone, triazolium tin suspending agent and other acaricides, and promoted in some fruit fields, so far no significant resistance has been found, the drug control effect is good The red spider and the rust tick are light, and the rust tick is less than 0.2%. Years of practice have shown that according to the control objects, the growth period of crops, meteorological factors, pest resistance, etc., the rational selection of acaricides for controlling citrus mites is to improve the control effect, reduce damages, and avoid or delay the occurrence of mites. An effective method for resistance and prolonging the service life of pesticides.
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