What are the common pests and diseases of Euonymus japonicus?

1. Box tree pyralid

The larva spins silk to connect surrounding leaves and tender twigs into a temporary nest, then feeds inside it; in severe cases it eats all the leaves, causing the seedling to die.

Morphological features: the adult has grayish-white body and wings; the front wing's costal margin, outer margin and inner margin have purplish-brown broad bands; on the purplish-brown band of the costal margin there are two white spots; the scales are glossy with a purplish-red sheen. The larva has a black head, a yellow-green body, dorsal line, subdorsal line and spiracular upper line from dark green to ink green, and the spiracular line is orange-yellow.

Occurrence pattern: in northern regions there are 2 to 3 generations a year; the larva overwinters in a thin cocoon inside the bud, and the adult hides by day and comes out at night, with phototaxis.

Control methods: (1) Manual capture: during the adult egg-laying period, combined with pruning the seedlings, remove egg masses and larval nests and burn them in a centralized way. (2) During the adult stage, use black light lamps for light trapping. (3) When larval damage is severe, spray 50% fenitrothion emulsion at 1000 times dilution; or 4.5% beta-cypermethrin at 2000 times dilution; or Bt emulsion at 500 times dilution (note: Bt emulsion must never be used together with fungicides; spraying is more effective after 4 p.m. on cloudy days).

2. Euonymus japonicus looper

The larvae gather on leaves to feed; after eating all the leaves they gnaw the tender twig cortex, causing the whole plant to die. It overwinters as a pupa; the adult's flying ability is not strong, and it has strong phototaxis.

Morphological features: adult - the female adult's wing base is silvery white with light gray markings of varying sizes arranged irregularly. The front wing's outer margin has continuous light gray markings, the median line is not in a row, there is a large spot at the end of the discal cell, and the wing base has a dark yellow, brown and gray mottled patch; the abdomen is golden yellow, with stripes made up of black spots in 9 rows. The male moth's abdomen has 7 rows of stripes. The larva is entirely black, the pronotal plate is yellow with 5 nearly square black spots, and the spiracular line and ventral line are relatively wide and yellow.

Control methods: (1) Taking advantage of the adult's phototaxis, use light trapping during the adult stage. (2) During the larval damage period, spray 50% fenitrothion emulsifiable concentrate at 500 times dilution or 4.5% beta-cypermethrin at 2000 times dilution. (3) Remove egg masses during the egg-laying period. In winter, turn over the soil around the roots to kill overwintering pupae.

3. Japanese wax scale

One generation occurs a year, overwintering as fertilized female adults on twigs and shoot tips.

Morphological features: female adult - the wax shell is grayish white or slightly flesh-red, oval. Male adult - the body is dark brown or brown, with the head and thoracic notum darker. Nymph - the wax shell is ovate to elliptical, with the back slightly raised.

Control methods: (1) Quarantine measures: when buying seedlings from other places, plant quarantine procedures must be strictly implemented to prevent artificial spread of the pest. (2) Strengthen garden maintenance and management: through maintenance and management, create environmental conditions unsuitable for scale insects to survive. Implement crop rotation, clean the garden in time, and burn fallen leaves, weeds and diseased or pest-infested branches in a centralized way to reduce the overwintering pest population base; apply fertilizer reasonably to enhance plant resistance. Prune reasonably to make it ventilated and light-transmitting, change the living environment of scale insects, weaken their reproductive capacity and reduce damage. (3) Chemical control: when the population density is not high, use a soft brush dipped in a small amount of dichlorvos diluted with water (1:50 to 100 dilution) to wipe them out. During the peak nymph period, spray washing powder diesel emulsion; 150 to 200 times neem oil emulsion; 1% matrine at 1000 to 2000 times dilution; 2000 to 2500 times Dali Sha, spraying once about every 10 days for 3 consecutive sprays. (4) Protect natural enemies such as parasitic wasps.

4. Peach green aphid

Wingless parthenogenetic viviparous females and nymphs gather on shoot tips and the undersides of tender leaves to suck sap and cause damage; the damaged leaves often carry white waxy secretions, which easily cause sooty mold, and in severe cases the branches and leaves turn black, affecting plant growth and ornamental value. In the Tangshan area, about 10 generations occur a year.

Control methods: (1) Protect natural enemies such as ladybugs and green lacewings. (2) Chemical control: choose 20% fenvalerate-monocrotophos emulsifiable concentrate at 2000 times dilution or 2000 to 3000 times imidacloprid powder for spraying.

5. Powdery mildew

It damages Euonymus japonicus leaves; affected plants show shrunken and deformed leaves, affecting growth. Powdery mildew is mostly distributed on the upper side of Euonymus japonicus leaves, rarely growing on the underside; individual lesions are round, and after the white lesions expand and heal together they become irregular.

Control methods: (1) Prune appropriately to enhance air and light penetration. (2) At the early stage of the disease, alternately spray 25% diniconazole at 1300 times dilution, 70% thiophanate-methyl at 700 times dilution, and 50% thiram wettable powder at 800 times dilution. If the disease is severe, pruning must be carried out, cutting off diseased leaves and burning them in a centralized way, and then spraying chemicals for control.

6. Euonymus japonicus leaf spot

When the damage is severe, it causes the euonymus to shed leaves early, forming bare branches, affecting ornamental value and even causing death.

The disease occurs on new leaves, producing small yellow spots that later expand into irregular large spots; the lesion edges are raised, with a relatively wide brown edge. Outside the raised edge there is an extending yellow halo, and the center is yellow-brown or gray-brown, densely covered with small black dots.

Control methods: (1) Select robust, disease-free seedlings for planting. (2) From early June to July, spray 50% carbendazim at 500 times dilution or 75% chlorothalonil at 500 times dilution, or 50% thiram wettable powder at 800 to 1000 times dilution for prevention to reduce the disease incidence, spraying once every 10 to 15 days for 3 consecutive sprays. (3) In winter, remove fallen leaves and burn them in a centralized way.

7. Euonymus japonicus stem rot

Stem rot is a major disease to which Euonymus japonicus is susceptible, and in severe cases it can cause the whole plant to die. One- and two-year-old branches are most severely affected; initially the stem turns brown, the leaves lose green, the tender shoots droop, and the leaves do not fall off; later the affected part of the stem turns black, the cortex shrinks, the inner bark tissue rots, and many tiny black sclerotia are produced. As the temperature rises, the affected area develops rapidly, and the pathogen invades the xylem, causing the whole plant to die.

Causes of the disease: the pathogen causing Euonymus japonicus stem rot is a fungus of the Deuteromycetes, which normally lives saprophytically in the soil. As the temperature rises, the soil temperature also rises, and the pathogen invades the seedling stem and causes damage. It is especially common in high-temperature, low-lying areas.

Control methods: (1) Strengthen seedling maintenance and management to improve their own disease resistance. (2) Use fully decomposed farmyard manure as base fertilizer, which can reduce the disease incidence of seedlings. (3) In summer, take cooling measures such as building shade sheds for young seedlings; for larger seedlings, methods such as planting ground cover plants or mulching the ground with grass can be used to destroy the environmental conditions for the pathogen to occur. (4) Promptly cut off diseased branches and burn them in a centralized way. (5) When there are few and small diseased seedlings, use a brush to apply 50 times 50% carbendazim solution or 50 times 25% diniconazole emulsifiable concentrate (propiconazole) to the stem at the early stage of the disease. When there are many diseased seedlings or during the peak disease period, spray all the seedlings with 800 to 1000 times 25% diniconazole emulsifiable concentrate or 500 to 600 times 50% thiram powder. Both methods are applied once every 7 days for 3 to 4 consecutive times, which can achieve preventive and therapeutic effects.