It mostly happens in hot and rainy weather. The infected leaves showed light brown spots at the initial stage, then gradually spread and expanded to near round or irregular shape, and the center of the spots showed dark brown to gray white, resulting in the dead and broken leaves. The control methods are as follows:
1. For the selection of culture soil, it is suitable to use slightly acid sandy soil.
2. In summer, we often pour water to clean the old leaves in time.
3. In the early stage of the disease, Bordeaux solution, 600 times of 75% chlorothalonil wettable agent or 1000 times of potassium permanganate can be sprayed once every 10 days or so.
In the early stage of the disease, small yellow or red spots appear on the leaves, and then the spots gradually expand, showing brown or reddish brown. In severe cases, the whole leaves and even the whole branches die.
The control methods are as follows:
1. Strengthen management, apply fertilizer reasonably, ventilate well, trim the branches and leaves of diseases and insect pests in autumn and winter.
2. When the new leaves are extracted, they should be sprayed with 150 times of 27% high lipid membrane immediately.
3. Spray 500-800 times of anthrax formic solution every other week, 2-3 times continuously.
Stem rot of cycads is characterized by rapid development and spread. If it is not found or controlled in time, it will cause a large area of disease, causing major losses. The control methods are as follows:
1. The soil must be disinfected when planting cycads.
2. Strengthen the management at ordinary times, pay attention to the drainage work, before Mei Yu, you can irrigate 100 times of methomyl solution for prevention.
3. In the early stage of the disease, the diseased part should be cut off in time, and the wound should be cleaned with 0.2% potassium permanganate solution, dried and then coated with chlorothalonil or carbendazim powder for prevention and treatment.
Cycads are placed on the balcony for maintenance. If the ventilation and light transmission conditions are poor, the leaves are vulnerable to scale insects. The control methods are as follows:
1. You can pour through the surface soil of the basin according to the proportion of 1:2 by mixing liquor with water. You can pour it once every 15 days or so and see the effect four times in a row.
2. The damaged leaves of Cycas can be soaked with alcohol or rice vinegar with cotton ball and wiped gently and repeatedly, which can effectively kill the adults and larvae.
