To grow tangerine, it is necessary to prevent the yak scale from harming the young fruit.

At present, citrus sagittal scale is one of the main pests in citrus orchards in eastern and northern Guangdong. More than 50% of citrus orchards in these areas occur in varying degrees, affecting production. The author made a systematic fixed-point and regular observation on the occurrence of citrus sagittal scale, and carried out a large-scale control experiment and demonstration, and achieved good results, which can be used as a reference for farmers.

Occurrence regularity

The main results are as follows: 1. Citrus sagittal scale is the central distribution in citrus orchards, which often occurs on one or more vigorous and shady citrus trees. Then spread around to the entire orange orchard, the hillside showed an extension from the central point to the piece, generally less in a large area of disaster; the tree completely closed insect population density is large, the victim is heavy; the tree is weak and poorly managed. For a fruit field, the population density of the tree in the center of the orchard is large, the damage is heavy, the surrounding edge population density is small, the injury is light, and the young tree population density is small, the injury is light. The short-distance transmission of citrus sagittal scale is mainly through the adjacent contact of branches and leaves, people in and out of the belt and the wind, while the long-distance transmission is mainly through the introduction of seedlings, branches and fruit transportation.

2. Citrus sagittal scale can produce three generations a year in eastern and northern Guangdong. The first generation of young scale appeared in early May, the peak period was in the middle and late May, the second generation appeared in mid-July, the peak period was in late July, and the third generation appeared in mid-September, the peak period was in early October. Due to the overlap of generations of the sagittal scale, the first day of the embryo eye of the first generation in this area is about April 21, and the first day of the young scale on the leaf is in the first ten days of May, with an interval of 14 days. The initial peak period is from May 12 to 16, the peak period is from May 18 to 21, and the last stage is from May 25 to 26. The distance between the first day and the peak period of the young scale is 14 ~ 17 days. The first generation of young scale mainly parasites on the old leaves, with a small amount of harm to new leaves and young fruits; the second generation mainly harms the new leaves or some young fruits; the third generation mainly harms the fruit, leaving a small amount on the new leaves.

Prevention and control countermeasures

According to the occurrence law of the sagittal scale, combined with the reality of the area, a scientific control strategy was formulated, that is, taking agricultural control as the basis, chemical control as the focus, universal treatment of the overwintering generation, ruthless treatment of the first generation, and picking treatment of the second and third generations. at the same time, we should pay attention to grasp the appropriate period of control, the correct methods of pesticide application and the key techniques of chemical pesticides in order to achieve the ideal control effect.

The main results are as follows: 1. the suitable period for control: in the young scale stage, because the wax is not formed, the resistance is weak, and the liquid is easy to invade the insect body, so it becomes the suitable control period for each generation. Especially in the relatively concentrated, neat and consistent of the first generation of young scale, the application of pesticide in the middle and late May can get twice the result with half the effort.

2. Methods of drug application: first of all, on the basis of strengthening agricultural control, strengthening the management of citrus orchards, cultivating strong trees and enhancing tree resistance, we should focus on pruning in winter and spring. The key points of pruning are residual branches and withered leaves, inner bore branches, drooping branches and shady branches with high insect population density, centralized treatment to reduce the source of insects, so as to improve the control effect. The second is to pay attention to uniform and careful application. The sagittal tip scale is small, with overlapping generations and overlapping leaves. Therefore, the pesticide should be applied evenly and carefully, the pesticide should be in full contact with the insect body, sprayed evenly under the tree, inside and outside the tree, and the key parts should be at the base of the tree, inner chamber and shady branches. The first generation of young scale spray mainly old leaves, seriously taking into account the new shoots; the third is a reasonable number of times of application, the overwintering generation is mainly combined with pruning and general application, to do a good job of clearing the garden in winter and spring. The first generation of young scale should be applied once in the peak period and once in the serious orange orchard, and the second and third generation should be treated by picking.

3. Chemical pesticides: the whole body of the sagittal scale is covered with wax, and the general pesticide control effect is very poor, so choosing the right chemical pesticide plays an important role in its control. In winter and spring, 150 times solution of turpentine resin mixture was used to control adult scale in winter and spring, and 40% fast culling or 48% Lesbon 1000 times solution was used to control adult scale, and the effect was very good.