Control of diseases harmful to orchids (3) virus diseases

Virus is a relatively primitive creature, it has no cell structure and can only replicate in host cells. Once infected, there is generally no specific drug for prevention and treatment, so virus diseases can only be prevented by improving environmental hygiene and planting techniques. At present, it has been found that there are more than 20 kinds of viruses that can infect orchids, including CyMV, CMV, DeMV, CyRV and so on. The method to prevent and cure virus disease: when the virus disease occurs, it is necessary to remove and burn the diseased plants in time, and disinfect the appliances with potions. At present, the better disinfectants used are: 2% formalin and 2% sodium hydroxide aqueous solution. Or 164 grams of anhydrous or 377 grams of trisodium phosphate containing crystalline water plus 1 liter of water. The common viral diseases of Cymbidium are:

1. Orchid mosaic disease

Also known as orchid necrotic mosaic disease, black stripe necrosis, etc., is a common orchid virus disease, its host is very wide, including Cymbidium, shrimp ridge orchid, Dendrobium, Paphiopedilum, Wandai orchid and so on. The victim is a brown streak between the veins, followed by a striped mosaic. Mosaic symptoms are obvious on new leaves and light on mature leaves. About 3 weeks after infection, the new buds appeared irregular yellowish spots, which became more and more obvious as the leaves grew, and then developed into brown or grayish-brown necrotic spots. The pathogen of this disease is caused by cucumber mosaic virus (CMV), national orchid mosaic virus (CyMV) and Dendrobium mosaic virus (DeMV). It is commonly seen in orchid strains cultivated in greenhouse and transmitted by juices, so it is easy to transmit virus by cutting tools such as scissors and fingers used in cultivation management, and water from the basin bottom of susceptible strains can also be transmitted.

Prevention and control methods:

When the virus disease occurs, the diseased plant should be removed and burned in time, and the appliance should be sterilized with 2% formalin and 2% sodium hydroxide solution, or 164 grams of anhydrous or 377 grams of trisodium phosphate containing crystalline water plus 1 liter of water.

2. Orchid necrotic spot disease

Also known as orchid necrotic spot disease, caused by orchid small spot virus infection, can be infected with Dendrobium, Cymbidium, Oncidium and so on. Generally, when the disease occurs on the leaves, there are not obvious markings on the leaves of the injured individuals at first, then the mesophyll cells collapse, and small yellow-brown spots with sunken surfaces appear. In serious cases, there are reddish black-brown disease spots, and the markings are irregular and slender, intermingled with ring spots.

Prevention and control methods: pay attention to improving environmental hygiene conditions at ordinary times, wash fingers and tools with soapy water during ramet, disinfect bowls and cultivation substrates in advance, and disinfect 2% formalin and 2% sodium hydroxide aqueous solution. Or 164 grams of anhydrous or 377 grams of trisodium phosphate containing crystalline water plus 1 liter of water. In addition, after the diseased plant is found, it should be cleared and destroyed immediately to control the spread of the disease.

3. Orchid ring spot disease

Orchid necrotic ring spot disease, also known as orchid necrotic ring spot disease, is the most common orchid virus disease. The pathogen is national blue ringspot virus (CyRV). Hosts include Cartland, Cymbidium and so on. Necrotic yellow ring spots or necrotic spots will appear on the leaves of the injured individuals, and the plants will be weak and dwarfed.

Prevention and control methods:

The main results are as follows: (1) to strengthen the daily management, when multiplying or changing pots to add soil, the damage to leaves should be reduced as far as possible to prevent the transmission of leaf juice friction.

(2) rational fertilization can not only promote the growth of orchid plants, but also reduce diseases.

(3) the infected individuals should be cleared in time, and the infected individuals should not be used as the reproductive female parent, and the virus-free orchid seedlings should be produced by tissue culture in the disease area.

(4) the infected individuals can also spray insecticides such as 1000 times of dimethoate, 1000 times of marathon or 1000 times of phoxim to kill aphids, and the effect is good.