Control Techniques of Powdery Mildew of Euonymus Japonica

Powdery mildew is common, which affects its ornamental and restricts its application in landscaping.

Symptoms: powdery mildew mainly harms the leaves of Euonymus tomentosa, and the disease spots are mostly distributed on the leaf surface, resulting in powdery mildew spots. When the disease is serious, leaf back and new shoots can also occur, resulting in leaf shrinkage and deformity, twisted new shoots, atrophy and stop growing, and lead to fallen leaves and withered shoots. In the early stage of the disease, there are many small white round spots scattered on the leaves, and with the gradual expansion of the disease spots, irregular large spots are formed, and even occupy the whole leaf surface. If the white powder layer on the surface of the disease spot is erased, yellow round spots can be found in the affected area.

Occurrence regularity: the pathogen overwintered in the damaged tissue or bud scale of Euonymus tomentosa with mycelium (i.e. gray membrane bacterial layer). In the spring of the following year, a large number of conidia were produced in the leaf expansion and growing period of Euonymus tomentosa, which was transmitted and infected by airflow, which became the bacterial source of the first infection of the disease. The pathogen parasitized on the surface of the branches and leaves of the host, produced haustorium deep into the epidermal cells to absorb nutrients, and produced a large number of spores to infect leaves and shoots many times in spring, summer and autumn every year. High temperature in summer is the main factor for the occurrence of diseases.

Prevention and control measures:

1. In order to improve the cultivation conditions, we should choose the land with high terrain, dry, sufficient light, no stagnant water and deep and fertile soil.

two。 Strengthen fertilizer and water management, increase the application of phosphorus and potassium fertilizer, appropriate amount of nitrogen fertilizer, pay attention to drought and drainage, make seedlings grow strong and improve disease resistance.

3. Reasonable pruning, cutting off diseased branches and leaves. Do a good job of clearing the garden in winter, sweep the diseased branches and leaves and burn them in a concentrated way, and the diseased branches found in the growing period can be cut off and burned in time, which can effectively reduce the source of primary infection and reinfection of the disease.

4. Rational use of pesticides for timely prevention and control, pay attention to the alternate use of agents, so as to prevent powdery mildew from producing drug resistance. Spray should be uniform, pay attention to spraying the inner chamber and leaf back. The mixture of stone and sulfur was used twice in winter, with an interval of one month. During the leaf development and growth period of Euonymus tomentosa, especially from April to May and September to October, the following medicaments can be used for control: 8-1000-fold liquid of Bietobacter shark, 2000-3000-fold liquid of Penicillium, 80-1000-fold liquid of 25% trimethoprim, 800-fold liquid of 70% methyl topiramate, 1000-1500-fold liquid of 50% benzoate, 50% acetaminophen 800-fold liquid and so on.