Osmanthus fragrans is also known as "laurel", "wood rhinoceros", "Yangui", "Julixiang" and "Qixiang". Leaves opposite, mostly oval or oblong, leaves the leaves smooth, leathery, leaf edges are serrated. The crown is spherical. The trunk is rough and gray. The flowers are clustered, and 3 to 5 buds are born in leafhoppers. From 9 to 10 months of flowering, many flowers were born in the spring shoots of the year, and they were also born on the second and third year old branches. The corolla splits to the base milk with white, yellow and orange red. Aroma special.
There are many varieties of sweet-scented osmanthus, and there are four common ones: Jingui, Yingui, Dangui and Siji. The fruit is a purple-black stone fruit, commonly known as Guizi.
Most of the common diseases of Osmanthus fragrans occur in leaves, mainly including Osmanthus fragrans brown spot, Osmanthus fragrans lithorrhiza, and Osmanthus fragrans anthracnose. These diseases can cause early defoliation of Osmanthus fragrans, weaken the growth potential of plants, and reduce the amount of flowering and ornamental value of Osmanthus fragrans.
Osmanthus Brown Spot
At the early stage of disease, chlorotic yellow spots appear on the leaves, gradually expanding into near-circular lesions, with a diameter of 2 to 10 mm, or irregular lesions due to lesions extending from the veins. The lesions are yellow-brown to gray-brown with a yellow halo surrounding the lesion. Brown spot generally occurs from April to October, and old leaves are more susceptible than young leaves. Pathogens use hyphae to overwinter on diseased leaves, and conidia are produced in the spring of the following year for initial infection. Conidia are transmitted by airflow and raindrops.
Osmanthus leaf spot
The pathogenic bacteria of the disease mostly invade from the leaf margins and leaf tips and occur at the leaf margins and tip of the leaves. At the early stage of disease, light brown dots appear on the leaves, gradually expanding into round or irregular shaped lesions, and then expanding into a nearly round or irregular large gray-brown spot with dark brown edges. Freckles occur from July to November and can occur throughout the year in sheds with poor environmental conditions. The germs were infested with conidia by wind and water. High temperature, high humidity, and poorly ventilated environment are conducive to disease. When the plant growth is debilitating and after the winter, the old leaves and the lower leaves of the plant are more severe.
Osmanthus anthracnose
The disease infected osmanthus leaves. At the early stage of disease, small spots of chlorosis appear on the leaves, gradually expanding to form round, semi-circular or oval lesions. The lesions are light brown to gray-white with reddish-brown edges. In wet conditions, pale pink viscous spore discs appear on the lesions. Anthrax occurs from April to June. The pathogens passed through the contaminated discs in the diseased litter and were spread by wind and rain.
Prevention
First, reduce the source of infection. Completely remove diseased leaves in autumn. Potted osmanthus must be removed in time. Second, strengthen the cultivation and management. Choose fertile, well-drained soil or substrate for planting osmanthus; increase application of organic fertilizer and potash fertilizer; planting density should be suitable for ventilation and light transmission, reduce the humidity of the leaf surface to reduce the occurrence of diseases.
Scientific use of chemical control. At the beginning of the disease, Bordeaux's solution is sprayed 1:2:200 times. After that, it can be sprayed with 50% carbendazim WP 1000 times solution or 50% Benzol WP 1000 to 1500 times solution. Severe wards should be soaked and disinfected with 1000-fold potassium permanganate solution when nursery stocks are planted.
Pest control
The main pest of family-cultivated sweet-scented osmanthus is alfalfa, commonly known as red spider. Once the disease is found, it should be immediately disposed of. It can be cleared by ticks, killed, and sprayed with tin (Triazole) tin. Spray the front and back of the blade evenly. Once a week, 2-3 times in a row, it can be cured.
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