Edible Mushroom Cultivation Techniques and Key Points for Pest and Disease Control in Michelia alba

The leaves of Michelia alba (white michelia) are fresh and emerald green, the flowers are as white as jade, and the fragrance is like that of an orchid, making it very appealing. However, it is often poorly managed and suffers from pest and disease damage, causing the leaves to turn yellow, the flowers to become small and lose their purity, and diminishing its ornamental value, which is disappointing. Common diseases of Michelia alba include chlorosis, anthracnose, and root rot; pests include scale insects, red spider mites, aphids, and slug moths.

I. Anthracnose.

It mainly occurs on the leaves. In the early stage, it shows as chlorosis with small yellow spots appearing, which then gradually expand into round or oval shapes. Several lesions merge into irregular patches, with a light brown center and dark brown edges. When the lesion occurs at the leaf margin, it is semicircular, causing the leaf to become somewhat distorted. In severe cases, the entire leaf withers, turns black, and falls off. This disease is a fungal disease, and the pathogen overwinters in the host's diseased tissues. Excessive watering of potted plants and excessively high humidity make the disease more likely to occur. It generally begins in early June, with July to August being the peak period.

The control method is: improve the watering method by pouring water from the edge of the pot, and do not use too much; combined with pruning, cut off diseased leaves and diseased shoots, and remove fallen leaves for destruction to reduce the source of the disease; during the spring rain and plum rain seasons, spray Bordeaux mixture at an equal-ratio 100 to 200 times dilution, 65% zineb at 500 to 800 times dilution, or 70% thiophanate-methyl at 1000 times dilution every ten to fifteen days, spraying three to four times in succession to suppress the occurrence of the disease.

II. Root rot.

It is a fungal disease. Excessive watering of Michelia alba or exposure to waterlogging can easily cause the root system to turn black and rot. In mild cases, growth is poor, and the leaves wilt and yellow and fall off; in severe cases, the entire plant dies.

Control method: striving to improve soil drainage conditions is an important measure for disease prevention. Watering should follow the principle of watering when dry and keeping it moist, and water thoroughly when watering, and pay attention to loosening the soil; during continuous rainy days, prevent rain from falling on the plant and promptly pour out accumulated water in the pot; place more broken tiles and other drainage materials at the bottom of the pot. When placed outdoors, it is best to prop up the flower pot with bricks to facilitate drainage; if the plant becomes infected during the growing period, chemical agents such as 65% zineb at 250 times dilution, 50% amobam at 250 times dilution, or 50% carbendazim at 500 times dilution can be used to irrigate the root soil.

III. Chlorosis.

Also known as lime-induced chlorosis, it is a physiological disease. If the potting soil is alkaline and water containing relatively high saline-alkali components is also used for irrigation, the leaves of Michelia alba, which prefers slightly acidic soil, will gradually change from emerald green to yellow-white, and in severe cases, localized leaf necrosis will turn brown.

Control method: after the disease occurs, immediately spray a 0.5% ferrous sulfate solution onto the leaf surface, once a week, spraying three to four times in succession, and at the same time apply alum-fertilizer water.

IV. Pests.

Michelia alba is sometimes harmed by scale insects and red spider mites. The affected plant's leaves turn yellow, and in severe cases fall off one after another, affecting growth and development.

Control method: regularly inspect the underside of the leaves. If a small number of scale insects are found, they can be caught by hand. When red spider mites are found, a sanitary sprayer can be used, filled with water, and three to four drops of dichlorvos or dimethoate added, then sprayed to kill them. If there is no sprayer, a small wooden (bamboo) stick can also be used, with a cotton ball tied at one end and dipped in dichlorvos, inserted into the pot for fumigation, and both can achieve good control results. Aphids occur between spring and summer, with the most severe occurrence from May to June, mainly harming new shoots in spring and summer. A 40% dimethoate 1000 times dilution or 25% phosmet can be used.