Symptoms and Control Methods of Euonymus japonicus Scab

Pathogen: fungus of the genus Colletotrichum, class Coelomycetes, order Melanconiales, subdivision Deuteromycotina

Symptoms: Euonymus japonicus scab mainly damages leaves and branches. On the leaf surface, circular or nearly oval spots 1 mm to 2 mm in diameter first appear, and later the diseased tissue dries up and falls off, forming holes. When new shoots are infected, dark brown circular or oval slightly raised lesions appear on the surface, like scabs, with a grayish-white center. Later, 1 to 2 small black dots, namely acervuli, form in the center of the lesions. In severe cases, leaves drop off, ultimately causing the branches to die.

Disease pattern: The pathogen usually overwinters in the soil and spreads and infects when suitable conditions occur. Mole crickets, click beetles, nematodes and others can all carry the pathogen and expand the damage. In addition, flowing water and maintenance operations can also spread the disease. Overcrowded plants, poor growth, extensive management, and wind and rain are conducive to the occurrence and spread of the disease. Conditions of high temperature, abundant rain and high humidity easily worsen infection.

Control methods

1. Strengthen management, enhance the growth vigor of the seedlings, and reduce conditions for disease occurrence.

2. In combination with pruning, cut off part of the diseased leaves and burn them.

3. Improve the planting environment, control plant density, and promote ventilation and light penetration, especially in cutting beds.

4. During the preventive period, spray 100 times equal-amount Bordeaux mixture, or 5 degree Beaume lime sulfur mixture.

5. During the disease occurrence period, use 65% zineb 500 to 800 times solution, or 50% carbendazim, 50% thiophanate 700 to 1000 times solution, chlorothalonil 1000 times solution, or thiophanate-methyl 1200 times solution, spraying once every 7 to 10 days, for 3 to 4 consecutive sprays, with good control effect.