Prevention and control of diseases harmful to orchids (2) bacterial diseases

Bacteria are also single-celled organisms and can only be seen under a microscope. The main damage of bacteria to plants is the production of toxins, causing plant decay or tissue death, or blocking and destroying vascular bundles, forming tumors. As the prevention and control of bacteria is difficult, the best control method is to prevent the occurrence of bacteria.

1. Orchid brown rot

It is one of the most common bacterial diseases in the world. the pathogenic bacteria are Orchid, Gladiolus and so on, which mostly occur in humid and warm environment. It is generally harmful to the buds or leaves of orchids. When injured, the leaves of the orchid plant first appear watery yellow spots, then gradually become chestnut brown, and may sink, and then the immersed place is brown rotten, often rapidly spreading to the continuous growing leaves, and then destroying the leaves, causing them to fall off. sometimes it harms the whole plant.

Control method: once the orchid plant is injured, the diseased leaves should be removed in time until only false bulbs are left, and then sprayed with 200 mg / L agricultural streptomycin or 0.5% Bordeaux solution, once a week, 3 times in a row.

2. Orchid soft rot

Orchid mosaic spot, also known as orchid mosaic disease, is easy to cause this disease when it is hot and humid, and it is more common in tropical Asia. The disease is more serious in southern China, which can be transmitted through soil, and can also be infected from wounds and insect pest food marks produced in transplanting and management operations. it can also spread with Rain Water or watering. The pathogenic bacteria are Monomonas Cartland, Eucalyptus and so on. In general, the disease occurred in the whole plant, mostly infected from the rhizome, and when the leaves were damaged, they were small spots in the form of dark green water immersion, which rapidly expanded and softened and rotted. The rotten part is leached by brown water droplets from time to time, which has a special stench, and when it is serious, the leaves turn yellow quickly. If the pseudobulb is susceptible, there will also be waterlogged spots, brown to black, which eventually make the pseudobulb soft, wrinkled and dark, and rot quickly.

Prevention and control methods:

(1) once the disease occurs, the diseased leaves should be cut off in time, and the wound should be smeared with Bordeaux solution.

(2) the diseased orchid plant can also be pulled out, soaked in 1% potassium permanganate solution for 5 minutes, washed and dried in the sun for 15 minutes before planting.

(3) it can also be sprayed with 0.5% Bordeaux solution or 200 mg / L agricultural streptomycin or methyl parathion.

3. Orchid leaf rot

Mainly infected with Wandai orchid, Dendrobium, etc., the pathogen is chrysanthemum Orchid, the damaged orchid leaves have translucent patches at the initial stage, Dendrobium leaves are yellow water stains at the initial stage, and finally the disease spots will become black and sunken. Finally, it can cause the whole leaf to rot and fall off.

Prevention and control methods:

(1) once the disease occurs, the diseased leaves should be cut off in time, and the wound should be smeared with Bordeaux solution.

(2) the diseased orchid plant can also be pulled out, soaked in 1% potassium permanganate solution for 5 minutes, washed and dried in the sun for 15 minutes before planting.

(3) it can also be sprayed with 0.5% Bordeaux solution or 200 mg / L agricultural streptomycin or methyl parathion.

4. Orchid brown spot

There are many kinds of Cymbidium, and the pathogenic bacteria are Pseudomonas cartland and Pseudomonas aeruginosa, which are easy to occur in high temperature, humidity and poor ventilation. It is transmitted from wounds or food marks of insect pests through cultivation materials, flowerpots, etc. It mainly harms the buds and leaves of Cymbidium. When it occurs on the leaves, it first appears soft, watery spots, and then expands into clear-cut, slightly sunken brown or black water-immersed spots, sometimes producing turbid droplets where the spots rot. Once this disease occurs, the disease expands very rapidly. it won't take a few days to kill the orchid plant.

Prevention and control methods:

(1) in the process of cultivation, we should pay attention to environmental ventilation and avoid watering "head water".

(2) if the diseased plant is found, the infected organ or the whole plant can be cut off according to the situation, and then sprayed with 0.5% Bordeaux solution or 100 mg / L agricultural streptomycin, or soaked in 0.1% potassium permanganate solution for 5 minutes, washed and dried before planting.

5. Bacterial flower rot

It mainly harms Cymbidium, Cartland and Paphiopedilum. The pathogenic bacteria were Pseudomonas and Pseudomonas fluorescens. They can not only parasitize dead plants, but also infect damaged tissues. Most of the infected orchid plants appear rotten spots on the flowers, including some small, necrotic spots, with waterlogged halos, and cause root, stem, bud, flower necrosis and decay.

Prevention and control methods:

(1) the most effective way to prevent and cure the disease is to change the culture soil and strictly disinfect it. The method of soil disinfection can be sterilized by high temperature or sprayed with 200 mg / L agricultural streptomycin and 0.5% Bordeaux solution.

(2) cut off the infected tissue and soak the infected plant with 0.1% potassium permanganate solution.