Oleander black spot
Symptoms: the disease spot occurs at the edge or middle of the leaf, showing a semicircle or circle, when several disease spots are connected to form a ripple, both sides have, the front is slightly darker than the back, and the disease spot is grayish white or grayish brown. In the later stage, there is a black powdery mildew layer in the disease, which usually occurs on the old leaves.
Pathogen and disease status: the pathogen is a fungus of Alternaria (Alternariasp.). The spores are transmitted by wind and rain. Too much Rain Water is easy to cause the disease, and the disease is common on the old leaves, lower leaves and tillering branches germinated in the roots.
Prevention and control measures:
1. Strengthen the management and enhance the ventilation and light transmission of the plant. Apply more phosphorus and potassium fertilizer to enhance the tree potential.
2. Spray 75% chlorothalonil 800 times liquid for prevention and control.
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Control of black spot of oleander
The symptom spot occurs at the edge or middle of the leaf, semicircular or round. When several disease spots are connected, they are corrugated, both positive and negative, and the front is darker than the back, and the disease spot is grayish white or grayish brown; in the later stage, a black powdery mildew layer is produced in the disease spot, which usually occurs on the overwintering leaves. The pathogen is fungus, Alternariasp. The conidia are olive-colored, oval, longitudinally and horizontally separated, chain-shaped, and borne on longer conidiophores. The general law of the disease is the old leaf and the lower part.
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Oleander management
Oleander, also known as half a year red, willow peach, originated in Iran and India. Because it is evergreen without deciduous leaves, double flower fragrance, red, yellow and white, easy to breed, simple to manage, long florescence and generous crown, it is loved by people. Both the south and the north of our country can be cultivated, potted and planted on the ground. They are often planted in courtyards and flower beds, as well as Jizhi. But the management of oleander must pay attention to three points: it must be pruned at the right time. The top branch of oleander has the characteristic of one-third, which can be trimmed and shaped according to the need. Such as
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