Control Techniques of Anthracnose and Leaf Spot of Euonymus Japonica

Euonymus chinensis is often used as hedge in garden. It has strong resistance to various toxic gases and smoke. However, the occurrence of anthracnose and leaf spot will make the plant defoliate ahead of time or even die, which seriously affects the ornamental effect of Euonymus chinensis. The two diseases often occur together, and there are two kinds of disease spots on the same leaf, but they can be prevented and treated simultaneously.

1. Anthrax

1. Symptomatic disease occurs on leaves and young shoots. Leaf lesions are elliptic or rounded and about 3 to 12 mm in diameter. There are narrow dark brown ridges at the edge of the disease spot, gray in the center, thick round or oval small black spots formed in the gray in the later stage, arranged sparsely, mostly in the front of the leaf, sometimes arranged in a striate shape. In the tender shoots on the disease spots strip, gray, black spots on its health, can cause branches to die. This disease is often mixed with leaf spot disease of Euonymus Japonica, the difference is that there is no yellow halo around the disease spot.

2. Pathogen overwinters in mycelium or spore disk in diseased branch and leaf tissue. In May and June of the following year, spores germinate at suitable temperature and often invade from host wounds. This disease parasitism is not strong, can only invade from the wound, occurs slightly later than leaf spot disease.

II. Leaf spot disease

1. Early symptoms, leaves have small yellow spots, gradually turning yellow, expanding into round or irregular spots, 2 to 10 mm in diameter, up to 15 mm, the edge of the lesion raised, brown edge wider, in the raised edge, there are extended yellow halo. The later stage of the disease spot is grayish brown or grayish white, the edge is dark, the center of the disease spot is chloasma or blackish brown, and small black spots are born on it. When the disease spot is serious, it is connected into one piece, and the leaves are withered and fallen off.

2. Pathogen overwinters on diseased leaves or fallen leaves in hyphae, diseased plants are latent places, spores are transmitted by wind and rain. In spring of the following year, with the temperature rising, conidia were produced and invaded from stomata, scissors and wounds. In Tianjin area, the disease usually begins to infect in June, the peak infection period is July and August, a large number of diseases occur from mid-August to September, and the disease spots expand and leaves appear when the disease is serious. General high temperature wet weather mildew serious disease, in addition, plant senescence will also aggravate the disease.

III. Prevention and control methods

1. Reduce the source of disease, collect diseased branches and leaves in autumn and winter, and burn them in a centralized way.

2. When selecting healthy seedlings for planting and seedling raising, healthy plants are selected to improve disease resistance.

3. Strengthen maintenance management, reasonable density planting, pay attention to ventilation and light transmission, reduce leaf humidity and reduce the incidence rate.

4. At the early stage of chemical control, spray 800-1000 times solution of Bijun shark, or 50% carbendazim 500 times solution, or 75% chlorothalonil 500 times solution in time. Uninfected plants should be sprayed for prevention. Chemical agents should be used alternately, spraying once every 7 to 10 days for 2 to 3 consecutive times. In areas with severe disease, infected plants should be uprooted, disinfected by irrigating the soil with fungicides such as Miaowenling 200-300 times solution for two or three times, and then replanted.