Orchid root rot

The disease is also a destructive disease in orchids, and it is susceptible to disease in all growth stages of orchids. There are many kinds of harm, such as Cartland, Oncidium, Paphiopedilum, Orchid, Dendrobium, Phalaenopsis, Magnolia and Orchid and so on.

The pathogen of the disease is Rhizoctonia solani (Rhizoctonia solani). Root rot is caused by mycelium and sclerotia (resting body) infecting the roots and rhizomes of seedlings. If not controlled, the rot can develop to stems and lower leaves. In the process of infection, a brown rot zone is formed around the plant, which first causes the seedlings to wilt and finally dies. When the adult plant is invaded, it will gradually weaken. Usually rot is limited to the root, causing root damage, but sometimes it can also extend to the rhizome and enter part of the pseudobulb. Plants with root rot decline and may eventually die. The leaves and pseudobulbs were yellowed, shrunk, thin and twisted. Orchids are most often damaged when they grow in bark or other potted mixtures that have been used or absorbed enough water, but newly changed plants can become ill even if they are properly drained.

In the aspect of control, the root and all the decaying parts of the diseased plant are generally removed and poured with 1000 times solution of benzoate; if there is the harm of ultimate Pythium or Phytophthora at the same time, the plant is irrigated with zolium mixture, and the dosage is also 1000 times of the solution.

In addition, there is an extreme rot caused by Pelllcularia filainentosa, a brown fungus that infects roots and the lower part of the pseudocorm, which can destroy seedlings and cause mature plants to wither in a very short time, turn yellow and die "without visible cause". The infected plants should be soaked in a biphenol solution of 1RU 2000, per 10L. Water plus thiram 20g or per 10L. The water must be treated repeatedly every 4-7 days in a solution of 25g of Dysen zinc containing 80% wettable powder. (Liu Zhongjian)