Control measures of soft rot of Cymbidium

Cymbidium belongs to the genus Amaryllidaceae and is a perennial evergreen herb flower. Since it was introduced into China from Japan in 1932, the soft rot of Cymbidium is a common disease in various areas of our country, which often causes the death of the whole plant and causes great economic losses. In order to prevent and cure the diseases of Cymbidium, we need to take targeted measures to prevent and treat them according to the characteristics of its symptoms.

Symptoms of soft rot

Soft rot is mainly harmful to pseudobulbs and leaves of Cymbidium. At the initial stage of the disease, the stem base appeared watery spots, and then gradually expanded into light brown spots, which spread to the pseudobulb, making the tissue rot soft and smelly. The stem-based disease spot can also expand to the leaf along the leaf vein, and the leaf shows water-stained spot at the initial stage, and then rapidly expands and rotts in a translucent shape. There is a yellow halo around the disease spot and a wide band around the halo. In severe cases, the whole leaf rotted and disintegrated as wet rot.

The pathogen of the disease is bacteria, mainly Erwinia chrysanthemum and soft rot Erwinia black stem disease.

Second, the law of the disease.

The pathogenic bacteria overwintered in the soil or the remains of diseased plants, which could occur from June to November, but most of them occurred in the period of high temperature and humidity in summer, and poor ventilation was beneficial to the spread and development of the disease. Bacteria can survive in the soil for several months, and diseased soil is an important source of infection. Therefore, the incomplete disinfection with soil can easily lead to the occurrence of this disease. In addition, it can be transmitted by means of contact and friction between water currents, insects, diseased leaves and healthy leaves or through operating tools. When the pathogen invades into the plant from the wound, it can occur within a few days, and it can be infected repeatedly in the growing season. In summer, if part of the stem heart of Cymbidium is drenched in the rain or inadvertently injected into the stem heart, the disease can be induced. In addition to infecting Cymbidium, the pathogen can also cause chrysanthemum, carnation, Dahlia, begonia, evergreen and so on.

III. Prevention and control of soft rot

1. Soil disinfection: in order to prevent the occurrence of soft rot in advance, disinfect the potted soil planted with flowers before transplanting. The soil can be disinfected with 0.5% Murray 1% formalin, about 10g per square meter; it can also be disinfected with chloropicrin 60--120g/ square meters or 70% pentachloronitrobenzene 8--10g/ square meters.

Used flowerpots and contaminated tools should also be cleaned and sterilized with 1% copper sulfate before use. Do not water too much at ordinary times, lest the basin soil is too wet.

2. Agricultural prevention and control: timely cutting or pulling out the diseased plants and destroying them; do not touch the plants during planting and transplanting to avoid wound infection; pay attention to drainage during the onset of the disease to keep the rhizomes dry so as not to damage the roots, rhizomes and bulbs.

3. Chemical prevention and treatment: 1000 times of agricultural streptomycin or 150 Mel 200 times Bordeaux should be sprayed every 1 month or so to control the spread of the disease. At the same time, when insect pests are found, it is necessary to prevent and control them in time to reduce the wound and reduce the incidence.