Osmanthus in our country has thousands of years of cultivation history, is one of the top ten famous flowers in our country, the branches and leaves are luxuriant, evergreen in all seasons, fragrant when flowering, ten miles of fragrance, in recent years in the northern region is also quite popular, in the process of its growth some leaf diseases often cause osmanthus early defoliation, weaken the growth potential of the plant, reduce the osmanthus flower yield and ornamental value.
1] Osmanthus anthracnose:
The disease infects osmanthus leaves, and at the beginning of the disease, small green spots appear on the leaves, which gradually expand to form round, semicircular or oval lesions. The lesions are light brown to grayish-white with reddish-brown rings around the edges. In moist conditions, pale peach-colored myxosporite discs appear on the lesions.
Anthrax occurs from April to June, and the pathogen overwinters in diseased leaf litter in conidia discs, which are spread by wind and rain.
2] Osmanthus brown spot disease:
At the beginning of the disease, small yellow-colored spots appear on the leaves, which gradually expand into near-round lesions, with a diameter of 2-10mm, or become irregular lesions due to the expansion of the lesions limited by the leaf veins, and the lesions are yellow-brown to gray-brown, with a yellow halo on the periphery.
Brown spot disease generally occurs from April to October, the old leaves are more susceptible than the young leaves, the pathogenic bacteria overwinter on the diseased leaves with hyphae, and produce conidia for initial infection in the spring of the following year, and the conidia are spread by air currents and raindrops.
3] Osmanthus blight:
The disease mostly occurs on the margins and tips of leaves. At the beginning of the disease, small light brown spots are produced on the leaves, which gradually expand into round or irregular gray-brown spots with dark brown edges.
Blight disease occurs from July to November, and the fungus is infected by wind and water transmission through conidia. High temperatures, high humidity, and poorly ventilated environments are conducive to the onset of the disease.
4] Osmanthus powdery mildew:
Powdery mildew is one of the common diseases of osmanthus, which is mainly manifested as white powder on the leaves, and the leaves turn yellow and brittle, which will cause the leaves to dry up and fall off in severe cases. Powdery mildew is mainly caused by fungal infections and is severe in humid, dark, and poorly ventilated environments.
Key points of osmanthus leaf disease control:
1. Increase ventilation and light transmittance: through daily pruning, timely removal of yellow leaf diseased plants, keeping the environment ventilated and dry, reasonable fertilization and watering, can effectively prevent and control the leaf diseases of osmanthus.
2. Chemical control: When powdery mildew, anthracnose, leaf spot and other leaf diseases occur in osmanthus, Qi Lin Tianjun + Zhidazhuang can be sprayed for prevention and control