Citrus red spider, a young guest on a spring day, is active in early spring and peaks in April and May, when the damage intensifies. When the temperature rises after May, the insect population density decreases, but from September to October, the insect population rises again, which is more insignificant. At this time when the spider mites are raging, we must take effective measures to protect citrus production!
The factors influencing the outbreak of citrus red spider are complex and diverse, among which climate, natural enemies, tree nutrition and overwintering base all play a key role, and temperature is often the dominant factor.
First of all, the influence of climatic factors on citrus red spider cannot be ignored. The high temperature in summer is not good for the survival and reproduction of spider mites, and when the temperature exceeds 30 °C, the development of spider mites is affected, and the mortality rate rises sharply. In addition, rainfall also has a certain effect on the population of citrus red spiders. Under the condition of moderate temperature, the number of red spiders will decrease by 45%~70% after the rain, with concentrated rainfall of about 30 mm. Rainfall has the effect of flushing insect bodies, especially on orange trees under the canopy and with scattered leaves.
Secondly, nutrition also has a certain effect on the distribution of citrus red spiders. Spider mites often shift in the order in which the shoots are pumped, first on the autumn shoots in the spring, then on the summer shoots, and then on the autumn shoots. This trend may be due to the better nutritional conditions of the newly extracted shoots. According to statistics, female mites usually lay much more eggs when they feed on young leaves than when they feed on old leaves.
Natural predators are also one of the factors influencing citrus red spiders. There are many kinds of natural enemies of citrus red spiders, including ladybugs, predatory thrips, lacewings, cryptopteras, flower bugs, parasitic fungi, etc. Protecting and utilizing these natural predators is essential to control the population of spider mites. In recent years, due to the overuse of chemical pesticides, many natural enemies have died in large numbers, destroying the ecological balance, thus prompting a large-scale outbreak of citrus red spider spiders. In the control of citrus red spiders, the protection of natural enemies must be fully considered.
Why are citrus red spider mites so difficult to control? First of all, red spiders are not insects, so many conventional pesticides are ineffective against them. Secondly, it is difficult for the current red spider drugs on the market to cover the four forms of red spider at the same time, including eggs, larval mites, nymphs and adult mites. Due to the large reproduction coefficient of red spiders and the frequent generations, multiple forms of red spiders may exist on one leaf at the same time. Therefore, it is quite difficult to find acaricidal drugs that are effective against all four forms at the same time. In addition, spider mites are small in size and relatively hidden, so it is difficult to achieve full coverage of spraying drugs, and it is easy to rebound after the effect of the drug. In addition, due to the large number of pests and diseases in the southern production area of citrus, frequent use of pesticides is required, which makes some natural enemies of pests and mites killed in large quantities, and spider mites have gained a high degree of resistance. The management of the southern production area is relatively difficult.
Since citrus red spider is difficult to prevent and treat, is there any magic trick? First, on the premise of ensuring the control effect, reduce the number and frequency of pesticide use as much as possible. The number of drug use of spider mites in the northern production area is significantly lower than that in the southern production area, which is not simply due to the high level of drug use by growers in the northern production area. The red spider in the northern citrus producing areas is easy to manage, mainly because it has been used less in history, the resistance of the red spider is low, and the orchard ecology is relatively intact. Therefore, the use of drugs still needs to be cautious, and the use of drugs must be scientifically organized under the premise of ensuring the prevention effect. Secondly, mineral acaricides such as mineral oil are preferred, although mineral oil is easy to pesticide, but spider mites cannot develop resistance to them. At the same time, mineral oil can also treat other pests and diseases. In addition, the protection and utilization of natural predators, such as thistle, is also an effective means. Finally, the quality of the spray is a prerequisite for all effects, and the spray must be carefully and thoroughly moistened to ensure that the drug covers the hidden areas of the spider mites.
In general, the prevention and control of citrus red spider needs to comprehensively consider multiple factors such as climate, nutrition, and natural enemies, and adopt scientific and effective management and prevention and control methods. Through the rational application of pesticides and the protection of natural enemies, we can effectively reduce the adverse effects of citrus red spider on yield and quality.