Orchid nematode disease and its control

The nematode Anguinaorchidii of orchids is called Nematode, which is a parasitic disease of orchids. This kind of worm belongs to the linear phylum, which used to be called Nemathelminthes, nematode class, nematode family. The nematode of orchid is the pathogenic parasite of orchid nematode disease. The body of the adult is linear and long cylindrical, sharp and thin at both ends, unsegmented, and the body is composed of three germ layers and has a protoplast cavity. There is no bend in the digestive tract, the front end is a kiss, there is a band ring about 10 microns long at the lower 0.5mm, and the back end is the cloacal door. The female worm is 5 mm long, the male worm is 2.5 mm long, and there are two spines on the tail. The nematode eggs are very small, less than 0.2mm in diameter, and the smallest is only 1 micron. The gall that falls into the plant material absorbs water and expands when the plant is wet. After the larva overflows, it invades the root quilt tissue, moves upward along the plant to the leaf or mesophyll tissue or the storage tissue of the root to absorb the nutrients of the orchid plant, stimulates the cortical cells, and causes the formation of the gall. After the adult population of nematodes matured, they mated and laid eggs in the galls. After the eggs in winter hatched into larvae, they stayed in the galls. When the earth returned to spring in the coming year, the larvae would spill out the gall shell, washed by Rain Water and irrigation, fell into the plant substrate, and then re-infected. In the plants with this insect disease, the insect began to migrate to the root integument and leaves of the host in early summer, and the leaves appeared phosphorus yellow dots when invaded from stomata or water pores, and the bottom surface could be seen. After the beginning of autumn, the yellow spot became a thick leathery scab gall, showing a round shape. The other parts of the leaf without galls had no pathological changes and grew normally. A fixed-point rough bend appears in the root, and then a flat nodular gall is formed. When the root is degenerated and dried up in winter, the living galls remain in the plant or culture medium. When the spring temperature rises to 18: 22 ℃, the gall larvae overflow and infect other roots and new individuals in the same basin. For the orchid plants parasitic with nematodes, most of the leaves become thickened and hard, and there are sores and demons, the tillers are abnormal, and most of them can not draw flowering stems.

The prevention and control of orchid nematode disease should be based on the principle of "prevention is more important than control". First of all, to strengthen the disinfection of the planting substrate, you can rinse with 1% potassium permanganate solution, rinse with clean water, and then use it after drying. When dividing the basin in winter and spring, the leaves with galls should be cut off, and the old roots and roots with galls and dried bracts should be cut off and burned.

Second, when it is found that there are round small yellow spots in the leaves at the beginning of spring, internal absorbent insecticides such as Mudan should be applied immediately; spray 3% on the leaf surface and back. Citric acid absorbs hexazine solution or 800 times rotenone solution, or sprays with 4% Satolen water agent; it can also be used to irrigate the plant material to make the root adsorb. In this way, the parasitic nematodes in the tissue can be killed within two days, and the plant is expected to recover and not form galls.

Third, if you are engaged in export or a large number of domestic sales, in order to ensure that the plant is free from nematode disease, disinfestation can be carried out before packaging and transportation. The process is divided into three steps: the first step is to wash the roots and leaves of the orchid plant with clean water; the second step is to soak the roots and leaves with 1% hydrogen peroxide or 1% potassium permanganate solution for 60 seconds, and then to dry them; and the third step is to soak 800 times fish vine semen for 15 minutes, take it out and dry it, and then box it. If there are any insects, they have all been killed.

The above points are my understanding of nematode disease, which can be used as a reference for people who love orchid and do business.

Shen Dezu