How to prevent and cure the mosaic disease of national orchid? what are the methods of applying fertilizer to orchids?

Symptom

The primary discoloration spot expands along the leaf vein, and the adjacent disease spot fuses to form a long strip discoloration spot, showing mosaic disease. After the leaves grow up, the discoloration stripes are necrotic.

Pathogen

National Orchid Mosaic virus (Cymbidiummosaicvirus,CyMV) occurs all over the world. The virion is about 480nm in length and 13nm in width. The virus is easy to be transmitted by mechanical sap. The virus naturally infects 38 genera of Orchidaceae and is the most widely hosted virus in Orchidaceae.

During the ramet and transplantation, the infected strain can be infected by taking the fingers and scissors of the susceptible strain to carry the virus. The root of the diseased plant is easy to be damaged, and the virus can flow out from the basin bottom when watering, so it is infectious.

Prevention and cure method

Prevention and control of orchid virus should give priority to prevention.

1. Destroy the diseased plant immediately after it is found. If it is a valuable variety, it should also be isolated to strengthen management.

2. During ramet propagation, fingers and tools are washed with soap water. Instead of using the same bucket of water to wash many plants, they should be washed one by one under running water. Potted soil, moss, potted bowls, etc., should also be disinfected before application.

At present, it is internationally recognized that the better disinfectants are: ① 2% formalin and 2% sodium hydroxide aqueous solution (which can no longer be used after turning green); ② 164g anhydrous trisodium phosphate (NaPO4) or 377g trisodium phosphate containing crystal water, adding 1000 ml of water, can be used for disinfection tools, cultivation environment, etc.

3. Fully mature seeds should be used when pollinating diseased plants as female parents.

4. Plants other than Orchidaceae such as Solanaceae, Leguminosae and Chenopodiaceae may also be infected with virus, which should be paid attention to in prevention and control.

Diagnostic method

The main results are as follows: (1) the discolored spots or long discolored spots on the leaves are in the shape of flowers and leaves, and then necrotic into dark brown spots.

(2) under electron microscope, the length of virion is about 480nm, which can be diagnosed as CyMV.

(3) diagnosis was made by CyMV antiserum test.

(4) Chenopodiaceae plants such as C.amaranticolor, apricot and Daturastramonnium,Cassiaoccidentalis can be used to indicate the inoculation reaction of plants.