Prevention and treatment of White Silk Disease of ornamental Flowers

White silk disease is a common disease of ornamental flowers. Its parasitic range is very wide, which causes the root and stem base of these flowers to rot after the disease. in serious cases, the whole plant dies.

White silk disease mainly occurs at the root and stem base of plants. Woody flowers generally begin to develop at the rhizome near the ground, and then spread to the upper and underground parts. The disease is brown at first, and then the cortex decays. The leaves of the injured plants lost water and withered, withered and fell off, the plant growth was stagnant, the flower buds were stunted, stiff and turned red. The main feature is that the diseased part is waterlogged, yellowish brown to reddish brown wet rot, on which there is a white silk mycelium layer, which often spreads to the soil surface near the diseased part, the cortex of the diseased part is easy to peel off, and the basal leaves are easy to fall off. Cymbidium and orchids occur in leaf stems and underground succulent stems. Flowers and plants with bulbs and bulbs occur on bulbs and bulbs. In the middle and later stage of the disease, sclerotia the size of yellow and white rapeseed often appeared in the white mycelium, and then became yellowish brown or brown, which became the source of re-infection. The sclerotia formed by flower white silk disease overwintered in the soil, and the sclerotia could survive in the soil for 5 to 6 years, but only for 3 to 4 months in water. When the environmental conditions are suitable, the mycelium produced by sclerotia is infected. The suitable temperature for the development of the pathogen is 32 to 33 ℃, the highest temperature is 38 ℃, and the lowest temperature is 13 ℃. Under the condition of high temperature and high humidity, the disease is serious and spreads rapidly; the disease is serious in continuous cropping land; acid sandy soil will also promote the occurrence of the disease.

Comprehensive measures should be taken to prevent and control the white silk disease of flowers: (1) put an end to the source of the disease. Remove diseased plants in time, remove sclerotia and diseased bodies that fall into the soil, burn them or bury them deeply, and spread lime in the disease holes to kill bacteria. Some sclerotia will be mixed in flower seeds. 10% salt water or 20% ammonium sulfate can be used to remove sclerotia, then rinse with clean water and sow. (2) pay attention to the selection of planting land, not continuous cropping of seriously affected plots, nor continuous cropping with crops easily infected with white silk disease, such as pepper, tea seedlings, pumpkins, peanuts and so on. (3) pay attention to drainage and fertilization in the garden, and strengthen the management to enhance the disease resistance of the plant. (4) Pesticide control. Timely use of drugs in the early stage of the disease can control the epidemic of the disease, pull out the diseased plants in time, and mix and disinfect with 70% pentachloronitrobenzene 1 to 2.5 kg per mu plus an appropriate amount of fine soil. Around it, lime powder and plant ash can be applied to prevent and cure the white silk disease of orchids. Plant ash is alkaline, which contains not only rich elements such as calcium, potassium and phosphorus, but also a lot of silicon. After root absorption, it can make the epidermal cells of orchid stems and leaves accumulate a layer of hard silicon and enhance disease resistance. In addition, the calcium in plant ash reacts with oxalic acid secreted by white silk pathogen, resulting in the death of the pathogen. After spraying plant ash, the hyphae subsided, the sclerotia dried up, and the milder ones could resume growth. in the more serious cases, the roots and pseudobulbs basically returned to normal, and new buds could sprout if they were managed properly. In order to prevent the occurrence of diseases, the plant ash leaching solution should be applied every 15 days or so, 2 to 3 times. Spraying 1% Bordeaux solution or 0.3 Baumite sulfur mixture also has a certain effect. In addition, 5% wettable anti-bacteria special soil can also be tried for prevention and control. (Cao Di Huan)