Symptoms: this disease usually occurs from March to July. If the seedlings grow too dense or weak, they will become seriously ill. In the early stage of the disease, there were purple spots on the tip or edge of the leaves, and then developed into round and semi-circular dark brown fog spots. The center gradually fades to white. When the humidity is high, grey brown mildew will appear on both sides of the lesion. It spreads through wind and rain and invades from the wound.
Prevention and control: in agriculture, it should be planted in a reasonable density, scientific management of fertilizer and water, cultivation of strong seedlings, not too dense. Once found, the diseased leaves should be removed as soon as possible and burned intensively to reduce the source of infection. In addition, the permeability of the environment should be enhanced. Some nurseries should use ventilators to speed up air circulation when necessary.
Symptoms: the branches and leaves of oleander are easily damaged by scale insects.
Prevention and control: combined with pruning, the branches and leaves of diseases and insect pests will be cut off and treated intensively to reduce the source of insects. The drug control can be treated by spraying 1200 times of 28% Jiebao emulsifiable concentrate or 800 times of 40% lesben emulsifiable concentrate and 1000 times of 10% imidacloprid. Improve ventilation and light transmission conditions.
Symptoms: the aphid mainly damages by sucking the juice of the branches and leaves of oleander. After the damage, the damaged leaf cells are damaged and the leaves curl and wrinkle. The growth of the plant was slow, the budding and flowering were delayed.
Prevention and control: when the number of diseased branches and leaves is small, it can be removed by brush. If serious damage is found, plants need to be sprayed with 10% imidacloprid or 10% Jinshiji 1500 fold solution. In addition, the method of mixing plant ash with water can be used to mix them in a ratio of 2:1, soak them for a whole day, and then take the filtrate to spray and kill the pests, which can effectively prevent and control aphids on the crops, and at the same time add potassium fertilizer to the crops to enhance the lodging resistance and wind resistance of plants and flowers. For example, adding a proper amount of trichlorfon into the plant ash liquid can enhance the contact killing and fumigation effect of the liquid medicine, and improve the killing ability to aphids and other pests.
