Whitefly is a common and easily overlooked pest in the citrus production area. It has the characteristics of a large number of hosts, miscellaneous feeding habits, easy migration of imagoes, and high reproduction speed. Once it breaks out, it poses a great threat to new shoots and fruits.
At present, there are 23 species of citrus aphid pests in China, of which the most serious are citrus aphid (whiteflies) and blackflies.
Black Locust
Four to five generations a year occur, with 2-3 instar nymphs overwintering in the leaves. From mid-March to late November, a variety of insecticidal black sting plagues can be seen between citrus trees, mainly affecting citrus spring, summer shoots and early autumn shoots.
Whitefly
It usually takes 3 generations, and waxy 3rd instar nymphs and crickets attach to the back of the leaves for winter. The flowering period of the flowering period from April to August and the growth period of the shoots and the fruit ripening period in October.
Major hazards
Whitefly pests are mainly adult, nymphs gathered on the back of the young leaves suck juice damage. Inhibit the growth of new shoots and weaken the tree vigor. When the damage is severe, it can cause leaf deformities and defoliation and cause shoot tipping.
Its honey-like secretions can easily induce leaf and fruit sooty, resulting in slow fruit growth, a small, dark skin, hard skin and taste acid, and even fruit drop. Therefore, in the peak period of occurrence of whiteflies in September, we must pay attention to strengthening prevention and control work.
The cause of a large number of whiteflies
1 Wide breadth of diet, abundant food sources, wide range of foods, such as privet, persimmon, etc. Many varieties of orange groves are mixed and planted. The growth period and management measures of different varieties are not the same, and new shoots are randomly selected. There are many kinds of intermediate host plants in the leaves of the Orangery and there are many kinds of intermediate host plants. It provides a rich source of food for citrus mealybugs.
2. Improper prevention and control methods The use of chemical pesticides, such as irrational use, excessive weed removal, etc., have killed natural enemies, such as citrifolia, and whiteflies, and reduced the role of natural enemies in the prevention and control of citrus aphid, thus making A lot of whiteflies occur.
3 Improper use of the drug Since eggs and larvae are small in size, light in color, transparent, and close to the color of foliage, they are not easy to detect and often miss the best period of prevention and treatment. Adult worms are easy to migrate and the spraying effect is not ideal. However, there is a shell protection during the falsification period and it is not easy to kill.
4 improper cultivation and management of citrus planting density is too large, canopy closure, plant foliage and cross light conditions, temperature and humidity conditions conducive to the growth of pests, and because the branches and leaves blocking each other, affecting the effect of spraying.
5 Clear garden work is not in place Winter clear garden or clear garden is not complete, citrus larvae or pupa winter larvae, the survival rate is higher, the breeding rate is faster, the next year the population base population is large.
Citrus mealybugs control measures
Agricultural control
When planting citrus, pay attention to the spacing, density and moderate, in order to prevent cross-linking branches, the size of the crown can be controlled by pruning to maintain good light and ventilation conditions.
Weeds are regularly removed to reduce the humidity, so that the humidity in the garden is reduced, which is not conducive to the growth and breeding of citrus mealybugs.
Do a good job in clearing the garden, especially in the winter, cut off the insects and burn them, and cooperate with the clearing garden to reduce overwintering pests.
Physical control
The citrus mealworms have a yellowing potential. Yellow sedation plates can be set in the citrus orchard to kill adults, and insecticidal lamps and traps can also be installed. Since the citrus mealworm adults prefer to shoot spawning, the hanging height and new shoots Flush is better.
Biological control
The natural enemies of the citrus mealybugs are widespread, and the natural enemies with the strongest control effects on them are the whitefly grasshoppers, knife-horned ladybugs and parasitic bees, which should be protected and utilized.
When spraying chemical pesticides, try to use pesticides that are less harmful to parasites, and do not use copper preparations and other broad-spectrum pesticides, which will help reduce the damage to parasites and exert their culling effects.
In heavy orchards where whiteflies occur, citrus foliage with parasitizing bacteria can be hung to increase the parasitism rate.
Chemical control
Grasp the key period of the 1~2 instar nymphs in citrus powder meal for key prevention and treatment. That is, at the peak of egg hatching (late March, late May, late July, mid-July, early August, and mid-October), it is recommended to spray buprofezin, thiamethoxam, and locust in the morning or evening. Such as the use of pharmaceutical rotation,
When spraying, focus on spraying the inner crown of the crown and the outer part of the leaves. When you hit the adult, pay attention to spraying it in the direction of its flight to kill it, so as to avoid the danger of immortality.
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