Pest control: pest control techniques of Euonymus tomentosa

Euonymus chinensis is an excellent evergreen broad-leaved tree species for urban landscaping and ecological environment improvement in northern China. Its planting quantity has exceeded 1 billion. Its stress resistance and ornamental performance are outstanding, and it can keep bright green leaves in winter. Hedgerow, large color block modeling and solitary planting are often used as main planting forms.

In recent years, due to the neglect of quarantine and treatment of diseases and insect pests in the inter-regional seedling exchange, the occurrence area of diseases and insect pests has expanded year by year. Some diseases and insect pests have developed into disasters due to late control, which may affect the growth and ornamental performance of plants in light cases or cause plant death in serious cases. In cultivation, common diseases and insect pests include the following:

1. Euonymus chinensis powdery mildew. It mainly damages the leaves of Euonymus Japonica, and when it occurs seriously, it can also infect the new shoots. In late autumn and winter, the pathogen overwinters with grey membranous layer, and in early April of the following year, when the temperature is above 18℃ and the relative humidity is 70-85%, i.e., the new shoots and leaves of Euonymus Japonica grow, the pathogen on the old leaves produces a large number of conidia, which are transmitted to the new leaves by wind and germinate on them, produce germ tubes, and finally invade the tissues. The newly infected leaves first fade green and produce macula, and then many round spots are scattered on the leaves. With the aggravation of the disease, the spots gradually expand and heal each other, becoming irregular large spots. Because this fungus parasitizes on the surface of host branches and leaves, it produces haustoria to absorb nutrients deeply into epidermal cells. Therefore, after new leaves are infected, wilting and water loss symptoms often occur, leaves become thin and shriveled, and diseased shoots are twisted and atrophied.

Control methods: ① appropriate pruning, enhance permeability. (2) At the early stage of disease, alternately spray 25% triadimefon 1300 times solution, 70% thiophane methyl 700 times solution, 50% tuijunte wettable powder 800 times solution. If the disease is serious, pruning must be carried out, the diseased leaves must be cut off and burned, and then spraying chemicals to control it.

2. Euonymus japonica brown spot disease. In late May of each year, when the temperature rises to about 25℃, the conidia produced by the old disease spots begin to infect the lower old leaves first. After the old leaves are infected, the primary brownish green spots on the leaves gradually turn yellow and turn brown. The disease spots are nearly round or irregular, and can be connected into pieces. The middle part is gray, and there are light brown slightly raised ring lines on the edge. Black dots are densely grown on the disease spots. Once the conditions are suitable, reinfection continues, the disease spreads from early June to mid July, and enters dormancy after October.

Control methods: ① select healthy disease-free seedlings for planting. (2) From early June to July, spraying 50% carbendazim 500 times solution or 75% chlorothalonil 500 times solution and 50% tuizonte wettable powder 800-1000 times solution for prevention, reducing the incidence rate, spraying once every 10-15 days, spraying 3 times continuously. (3) Defoliation is removed and burned intensively in winter.

3. Aphids. Female aphids and nymph aphids swarm on the tips of branches and the back of tender leaves to suck juice. White waxy secretions are often found on the injured leaves, which is easy to cause coal pollution. In severe cases, branches and leaves turn black, affecting plant growth and ornamental value. It usually occurs about 10 generations a year.

Control methods: ① protect ladybugs, large chrysopa and other natural enemies. (2) Chemical control: 20% Jusha EC 2000 times solution or 2000-3000 times imidacloprid powder can be selected for spraying.

4. Tortosuke japonica produces one generation a year, overwinters as fertilized female adults on branches, and hatches from mid-June to early July.

Morphological characteristics: female adult, wax shell white or slightly red flesh, oval. Male adult, dark brown or brown body, head and thorax dorsal plate darker. Nymph, wax shell ovoid to elliptic, dorsum slightly raised.

Prevention and control methods: (1) quarantine measures. When purchasing seedlings in different places, plant quarantine procedures must be strictly implemented to prevent artificial spread of pests. (2) Strengthen landscape conservation management. Environmental conditions unsuitable for scale insects are created through conservation management. Implement rotation planting, clear the garden in time, burn the fallen leaves, weeds, pests and other branches in a centralized manner, reduce the population base of overwintering pests, apply fertilizer reasonably, and enhance plant resistance. Reasonable pruning, increase ventilation and light transmission, change the living environment of vector pests, weaken their fecundity and reduce harm. (3) Chemical control. Insect density is not high, available soft brush dipped in a small amount of dichlorvos water (1:50-100 times the solution) to kill or remove the victim branches concentrated burn. At the peak stage of nymph, spray 40% omethoate 1000 times or deltamethrin 2500 times, spray once every 10 days or so, spray 3 times continuously. (4) Protection of natural enemies such as parasitoids.

5. Euonymus euonymus L. It has three generations a year and overwinters as pupae on the litter layer of the soil surface. Overwintering adults begin to emerge at the beginning of April, the peak of emergence is in the middle of April, eggs are laid 1-2 days after emergence, the peak of eggs is in the middle of April, and the egg period is 6-7 days. The larvae of the first generation appeared from late April to mid May, the larvae of the second generation appeared from mid June to early July, and the larvae of the third generation appeared from early August to early October. A few larvae overwinter in early September. The damage is most serious in late April to mid May and late August. The larvae gather on the back of host leaves to peel mesophyll 3-4 hours after hatching, and disperse to feed on leaves after 3 instars. When the density of insect population is high, there can be as many as 30-50 insects on a tree. When there is no food, petioles and new shoot cortex are also eaten, which seriously affects the growth of tree vigor and even causes tree death.

Control methods: ① use of adult phototaxis, in the adult stage of light trap. (2) Spraying 50% fenitrothion EC 500 times or 4.5% beta-cypermethrin 2000 times solution at larva damage stage. (3) Eradicate egg mass during oviposition period. Tillage root soil in winter to kill overwintering pupae.