Treatment of Leaf spot of Euonymus tomentosa

Euonymus tomentosa is a small evergreen shrub commonly used in gardens, which has many advantages, but the occurrence of leaf spot will cause early defoliation, bald branches and even death, which seriously affect the normal growth and ornamental effect of Euonymus tomentosa.

Symptoms of leaf spot disease: in the early stage of the disease, there are small yellow spots on the leaves, which gradually become yellowish brown and enlarge into round or irregular spots with a diameter of 2 mm to 10 mm. The disease spot is grayish brown or grayish white in the later stage, and the edge is deep. There are many small black spots on the disease spot, and when the disease spot is serious, the disease spot becomes one, and the leaves wither and fall off.

Disease regularity: the pathogen overwintered on diseased leaves or fallen leaves in the form of hyphae, which was the source of primary infection. Spores are transmitted by wind and rain. With the rise of temperature in the following spring, conidia were produced and invaded by stomata or scissors and wounds. The infection began in June in Tangshan area of Hebei Province, and the infection was at its peak in July and August, with symptoms in the middle of August. From mid-late August to September, the disease was serious with enlarged spots and fallen leaves. The severity of the disease is directly related to the air temperature and the amount of rainfall, and the disease is serious in years with high temperature, rainy and wet. The leaf spot of Euonymus tomentosa is easy to occur with shell insects and aphids, which aggravates the disease of the plant. It is easy to lead to diseases when extensive management, poor drainage, over-dense planting and poor ventilation.

Prevention and control measures: in line with the principle of "giving priority to prevention and combining prevention with prevention". Efforts should be made to enhance plant disease resistance from the aspects of plant selection, planting and management. When diseases occur, they should be treated early, small and well, so as to restrain their development.

1. Eliminate the source of infection: remove the diseased fallen leaves in winter, burn or bury deeply, and eliminate the source of infection.

2. When planting and raising seedlings, strong plants should be selected to improve disease resistance.

3. Strengthen maintenance and management: select plots with good drainage and moderate fertility to facilitate plant growth, enhance tree potential and improve disease resistance. Reasonable close planting, pay attention to ventilation and light transmission, reduce leaf humidity and reduce morbidity.

4. Chemical control: the initial stage of pathogen infection is the best period for control. Drug control of Euonymus tomentosa can well control the further development of the disease. The common chemicals are 1500 times of Bordeaux, 75% of thiophanate, 50% of carbendazim and 75% of chlorothalonil. Chemicals should be used alternately and sprayed every 7 to 10 days. The effect is good for 2 to 3 consecutive times.