Symptoms of soft rot of Cymbidium

Gentleman orchid, also known as Lycoris radiata, Lycoris macrophylla, is a more common flowering plant, but also a variety that many flower friends like very much. But in the hot summer, the gentleman orchid is very easy to get sick, soft rot is more likely to occur in the summer.

Gentleman orchid

Soft rot mainly harms pseudobulbs and leaves of Cymbidium. At the initial stage of the disease, the leaves were damaged, the heart leaves and the base of the heart leaves showed dark green waterlogging-like disease spots, the diseased leaves rotted and became soft and sagging, spread to the root system to make it mushy, the center of the leaves fell off, and the whole plant died. The pathogen of soft rot is Euclid bacilli, the lesion begins from the base of the plant, and then the leaves begin to rot, and the leaves and stems rot into paste and have a bad smell. After 2 to 3 days, the disease part of the leaves shows a sticky and soft rot-like "stem rot" lesion. The outer leaves were good, the heart leaves were rotten, the leaves and stem bases were good, the leaves rotted locally, and the whole leaves rotted and spread gradually within 12 hours, and the diseased part showed water-immersed "rotten leaf" lesions, and the rotting roots and leaves wilted. The root system showed a purulent "rotting root" lesion. The pathogen of soft rot is mainly overwintering in the residue of diseased plant and soil. The disease is easy to occur in summer with wet rain, high temperature, poor ventilation and application of a large amount of unrotten fertilizer.

Control of soft rot of Cymbidium

Cymbidium soft rot, also known as Cymbidium bacterial soft rot, Cymbidium root rot. It is a common disease of Cymbidium, which occurs in the cultivation areas of southern and northern China. The disease often causes the soft rot of the leaves, which spreads down to the stem, affects the ornamental in light cases, and lodging in the whole plant in severe cases.

Symptoms: it mainly harms the leaves, stems and roots of Cymbidium. In the early stage of the disease, water-stained dark green disease spots appeared on the leaves, which gradually expanded and spread, and the diseased tissue showed brown soft rot, with a clear boundary with healthy tissue. In the later stage, the disease part was dry and sunken, and in severe cases, the whole leaf soft rot sagged and separated from the stem. The infection of the stem went up to the base of the leaf and down to the root, causing the root to rot, the whole plant withered, and the leaf soft rot removed. Disease regularity: the pathogen is Erwin's soft rot bacillus. The pathogen survived and overwintered with the remnant of the diseased plant, spread by Rain Water, irrigation water and insects, and mostly invaded the plant from the wound. The bacteria invade and secrete Pectinase to dissolve the glue layer, resulting in cell rupture, cell sap overflow and soft rot. The development temperature of bacteria is 2: 40 ℃, and the optimum temperature is 25: 30 ℃. Summer high temperature, high humidity, poor ventilation in facilities, many plant wounds, serious damage to shell insects, etc., easy to occur and serious harm.

Prevention and control methods:

(1) strengthen management. Pay attention to watering from the edge of the basin, do not pour water into the heart leaf, if you inadvertently pour water into the heart leaf, you can use skimmed cotton to dip the stagnant water into the heart leaf. Pay attention to ventilation in the facility, timely control shell insects and other pests. When transplanting and pouring pots, prevent them from touching leaves and stems, causing wounds.

(2) cut off the diseased leaves when the disease is mild, and spray the whole plant, you can choose to spray: 50% copper succinate wettable powder 4000 times, 72% agricultural streptomycin sulfate soluble powder 4000 times, 77% killing wettable particulate powder 500 times, 47% Ruinong wettable powder 800 times 1000 times, spray once every 10 days, 2 times continuously.

(3) when the disease is serious in the leaves, but the roots and stems are not rotten, or when a few roots rot, the diseased plants can be uprooted, the diseased leaves and roots can be cut off, the soil can be washed with clean water, soak in 0.1% potassium permanganate solution for 5 minutes, then rinse with clean water, put the roots up in the sun for 30 minutes, and then dry for 4 days. Flowerpots and pot soil should be disinfected at high temperature, put on the pot after cold penetration or discard the original soil, prepare new aseptic soil, and choose new pots for planting. When planting, do not bury too deep, pour enough water in a cool place, slow the seedlings for 10-15 days to grow new leaves.

(4) if the root or stem has rotted completely or mostly, it should be removed in time, and the soil should be disinfected with quicklime. If it is a potted plant, the flowerpot should be disinfected, and the soil should be discarded and replaced with new soil.

Control methods 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 disease of Cymbidium, we need to take targeted measures to prevent and treat according to the characteristics of its symptoms.

First, symptoms

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.

Pathogenic bacteria overwintered in soil or in 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 methods

1. Soil disinfection: in order to prevent the occurrence of soft rot in advance, disinfect the potted soil of flowers before transplanting. The soil can be disinfected with 0.5% formalin, about 10g per square meter, or 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 control: the spread of the disease can be controlled by spraying agricultural streptomycin 1000 times or Bordeaux solution every 1 month or so. 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.