The occurrence of kiwifruit infestation will directly affect the yield, quality and commerciality of kiwifruit, of which the tick is the most important one. Ticks are commonly known as "tree lice", mainly parasitic on the branches of kiwifruit, by sucking the sap of the kiwi tree to cause damage to the tree, the affected part due to nutrient deficiency and other reasons can not develop normally and depression, resulting in uneven surface of the branch, a large number of fruits fall off.
Not only that, but the honeydew excreted by the insects will also induce coal pollution, which will cover the surface of the branches and leaves with a layer of black mold and hinder photosynthesis. April and May is the time of the activity of the scale insects, and it is helpful to know in advance the factors that may cause the infection of the insects and the symptoms after the infection of the insects.
There are many species of scale insects, the main harm to kiwifruit are grasshopper and mulberry shield bug, which have the same appearance and symptoms after infection. The larvae are oblate ovoid, yellowish brown, and about 8 to 10 days later many white translucent filaments begin to grow on the back of the body, which is their shell.
Shellworm larvae
After growing a bug shell
In general, females of the insect shell worm parasitize to the new buds in mid-March and begin to suck the sap of the tree. Grow rapidly by sucking juice. After that, it will crawl scattered to the 2 to 3 year old branches for fixed feeding. Spawning begins from late April to early May, and after laying the eggs, it shrinks to death, leaving the white shell on the branches and not falling off for a long time.
Therefore, the symptoms of the insect infection are actually very obvious, that is, a white powder layer is attached to the branches like patches. In severe cases, the shells overlap densely, and the branches are like a layer of cotton wool hanging on them.
The long-distance transmission of insects is mainly based on the transport of seedlings, scion, rootstock and other striped insects. Close propagation and spread mainly rely on the crawling of young nymphs, but also reliable for human thinning, fruit thinning, pruning, grafting and other field operations, and will also be carried by birds and other insects, or spread by wind, rainfall, and flowing water. Close planting is also one of the reasons why insects occur in orchards.
Once the insects enter the orchard and are infected, they lay their eggs. Insects tend to lay their eggs in tree crevices and die soon after spawning. The resulting eggs overwinter in piles in the soil near the rhizomes in the winter, and when the weather conditions are right, they begin to grow and become active. Therefore, orchards that have been infected with a bug once, if they do not do a good job of clearing the garden in winter, there is often a high probability of re-infection in the next year.
The survival of the insect has a lot to do with climatic conditions, and it is more likely to survive and be active in sunny, windy, and moist soil areas. When the eggs are latent, the shady slopes and years with low temperatures will make the eggs less likely to hatch and the incidence of the disease will be lighter. During the spawning period (April-May), the higher the soil moisture content and the higher the temperature, the greater the amount of eggs laid; when the soil moisture content is low, the amount of eggs laid will be reduced accordingly.
Because the body of the insect is wrapped in a thick waxy layer, it is very difficult to control the drug, so it is also listed as the first of the "five small pests" in the garden. Therefore, for the insects, we often adopt the strategy of prevention and treatment, and are more inclined to use physical control and biological control.
The so-called physical prevention and control is to carry out prevention and control in agricultural operations and management. The main ones are:
(1) Remove the source of insects: dig up soil cracks, stone crevices, weeds, fallen leaves, egg blocks, and combine winter and summer pruning, prune and remove insect branches, all burned, in order to reduce the density of insect populations and thus reduce insect pests.
(2) Try not to prune and harvest trees during the occurrence of grasshoppers, strictly control and test whether new seedlings carry grasshoppers, and do a good job in disinfecting seedlings.
(3) Reasonable fertilization, timely watering, enhance the plant's resistance to diseases and insects. Pay attention to the appropriate amount of watering, and the soil with higher humidity will provide more suitable living conditions for the insects.
(4) Use sticky shellac: before the insects are on the tree, at the trunk 60-70cm away from the surface, first scrape off a circle of old coarse skin, apply a circle of 10-20cm wide sticky shellac, when the insects are on the tree, they will be glued to death. Throughout the nymph tree period, pay attention to maintaining the viscosity of the glue, pay attention to inspection. If the viscosity is not enough, or there are too many sticky dead insects, it is cleaned up in time and applied again, generally 2-3 times.
Biological control: that is, the use of natural enemies to control and control natural enemies, reasonable protection of natural enemies or appropriate introduction of natural enemies, such as flower-winged jumping wasps, aphid-eating wasps, ladybugs and predatory mites. Try not to spray at the beginning of the emergence of natural enemies, and use pesticide application methods with low lethality to natural enemies, such as injection, coating and root burial, etc., and if necessary, artificial breeding and introduction of natural enemies for stocking.
Chemical control: At this stage, if the shell insects have not yet been found on the tree, spray the tree body with 3-5 baumedo stone sulfur compound, or 95% mite emulsion (oil emulsion) 50-70 times and so on. If there are already insects on the tree, you can also apply a brush dipping medicine to the surface of dense swarms of insects. It is best to use chemical agents to control different species of ticks, for example, the best control of grasshoppers is 22. 4% spironoid ethyl ester Sc, the best effect on the control of mulberry shield silkworm is 31% thiazideone • phosphorus killing EC, the use of the pen dipped in the liquid back and forth brushing the branches and trunks 2-3 times.