The nemesis of Orchid White Silk Disease-Plant Ash

Carry forward the national orchid culture and spread the knowledge of orchids

After reading the article on the treatment of white silk disease written by Zhou Weiqi in Zhejiang Province in the first issue of Chinese Orchid in 1999, I have the same feeling: the white silk pathogen of orchid is stubborn and grows rapidly, which often causes the orchid plant to die in a few days after the disease. general fungicides such as potassium permanganate and methyl thiophanate are basically ineffective, and there is a great possibility of recurrence. Zhou Weiqi consulted orchid experts and subdued white silk disease with "orchid fungus insect net" and "Dakening" ointment. This method is good, but it is only a passive treatment of white silk disease, which is limited to the initial stage of the disease (within a day or two). Even if the orchid is saved, it will greatly affect the growth of orchid seedlings.

This paper introduces to Lanyou an active prevention and control method of white silk disease which can promote the growth of orchids: sprinkling plant ash. It was 1993, when I was working in the state-run nursery in Longchang County, I was also in charge of the county nursery Orchid State. At the beginning of June, it was found that the buds of several boxes of longanin and osteoporin died. Take a closer look at the basin noodles and basin soil there are white silk, some orchid leaf long have rapeseed-like particles a sclerotia, the terrible white silk disease occurred.

A week later, the white mycelium grew out of the box again. As soon as I poured out the basin soil, the white mycelium almost filled the basin. At the same time, several new boxes were found in the garden to feel the disease. Do not dare to snub, quickly consult professional books, the causes of my illness and preventive measures. The pathogen of the disease is Sclerotinia uniformis. It belongs to Lanzhi fungus. The pathogen survives on the remains of diseased plants, weeds or soil with mycelial sclerotia. The optimum temperature for the growth of the pathogen is 29 ~ 32 degrees Celsius. In the season of high temperature and humidity, the disease is serious in the environment with high acidity of soil, so it can be controlled by carbon and other sterilized soil. According to the characteristics that white silk disease is suitable for growth in acidic environment, plant ash was applied once to the national orchid pot soil. Plant gray alkaline, can ease the acidity of basin soil, has germicidal function, and contains potassium, calcium fertilizer, can promote the growth of orchids. For the susceptible orchids, the above-mentioned conventional method was used to add a soaking procedure with plant ash water, and then sprinkled a thin layer of hydrated lime on the basin surface. In this way, the germs were subdued, but the infected orchids only saved 40%. After spreading plant ash in the garden, no new susceptible orchids were found, and the orchids grew well.

In 1994, in May before the arrival of Meiyu, absorbing the control experience of 1993 and striving for the initiative, hundreds of pots of orchids with Miaopu Orchid were comprehensively sprinkled with plant ash. As a result, there was no sign of white silk disease that year. The spreading method is: apply the ash of vegetation, that is, the ash of grass, wood and leaves after burning, spread on the surface of the basin soil under the orchid leaves, the amount should be 1 mm thick, and wash the leaves with clean water spray after application.