How to prevent and control soft rot in cyclamen? Key points for identifying common diseases

Cyclamen

The cyclamen, with its colorful flowers and green leaves, is a perennial herbaceous plant. Its flowers rise from the top of the tuber, very distinctive and bold, and are much favored by young girls. However, such a flowering plant is very prone to soft rot when improperly cared for, and diseased cyclamen severely affects both ornamental and economic value. For details on what cyclamen soft rot actually is, please see the introduction below.

I. Pathogen

Erwinia bacteria, belonging to the bacteria.

II. Symptoms

The pathogen of cyclamen soft rot is mainly spread through watering and fertilizing on the leaf surface, and mainly harms the leaves. After infection, water-soaked small spots appear on the leaves. The lesions are initially white or pale yellow, gradually turning dark brown. On sunny days the leaves turn brown and yellow and gradually dry up. The internal tissue of the affected area is decomposed by bacteria into a watery liquid, and the leaves lose their support and droop. After the leaf base or heart leaves are infected, on cloudy days the petioles and flower stalks soften and quickly wilt and fall over, gradually spreading to the tuber. Under humid conditions, the external tissue of the affected area swells, ruptures and rots with a foul odor, and the internal tissue turns dark brown, feeling sticky and soft to the touch, often causing the entire plant to die within a few days.

III. Occurrence patterns

The pathogenic bacteria overwinter and survive in the soil. The pathogen spreads through flowing water, insects and contact between diseased and healthy leaves, invading through wounds, and disease can develop within a few days after invasion. Multiple secondary infections can occur during the growing season, generally from June to September. High temperatures and frequent rain, and plants with many wounds, make disease likely, and excessive moisture makes it severe. However, in winter, if humidity is too high, exceeding 20°C for a long time, or if plants are bruised during operations, disease also commonly occurs.

Cyclamen

IV. Prevention and control methods

1. Preventing soft rot should begin with planting seedlings. First, disinfect the flower pots with 0.5%-1% formalin solution; or expose them to the sun in the open for 2 weeks on sunny days when the daytime temperature is above 30°C, using ultraviolet rays in sunlight to kill the pathogen; soil can also be heated to eliminate bacteria in the soil. For tubers, disinfect with 1:80 formalin solution or soak the seeds in potassium permanganate.

2. Strengthen cultivation management. Water in appropriate amounts to avoid overly wet potting soil. If watering is truly necessary and some plants are already diseased, remove the diseased plants two days before watering, and at the same time dig out the soil around the roots of the diseased plants and sprinkle some quicklime or plant ash, loosen the soil and then sprinkle some quicklime on the soil surface, or spray a fungicidal agent. Second, apply fully decomposed fertilizer, pay attention to ventilation and cooling during high temperature and humidity, and promptly control pests such as scale insects to prevent wounds caused by pests. Finally, do not bruise the plants when planting and transplanting, promptly prune diseased leaves and flowers and remove diseased plants for destruction, reducing sources of infection and avoiding mutual contamination.

3. In the early stages of disease, spray or drench the roots with 400-600 times streptomycin or oxytetracycline for control, or spray 72% agricultural streptomycin sulfate soluble powder at 3000 times dilution and other agents, once every 10 days, for 2-3 consecutive treatments.

4. When the disease is relatively severe and part of the root base has rotted, peel off the diseased part, soak the remaining rhizome in a disinfectant solution for 3 hours, then plant it in plain sand, and before long new roots will grow and new shoots will emerge, after which it can be replanted in sterilized potting soil.

Editor's tips:Never confuse cyclamen soft rot with cyclamen stem rot turning to water, because stem rot turning to water is mostly caused by overwatering. The symptoms are very similar to soft rot, but the causes are completely different, so the prevention and control methods also differ!

Prevention and control of common pests and diseases of cyclamen

Prevention and control of common pests and diseases of cyclamen

Common diseases of cyclamen include:Bacterial soft rot, gray mold, anthracnose, leaf spot and root-knot nematode disease. The control methods are as follows:

Bacterial soft rot:Caused by bacteria of the genus Erwinia. It mostly occurs at the petioles and tubers. Lesions on the petioles are initially light brown small spots, water-soaked soft rot. After expansion, the diseased tissue becomes soft-rotted, swollen, ruptured, with the epidermis separating and a foul odor. After tuber infection, the tissue turns yellow-brown, soft-rotted and mushy. It is prone to occur during the growing season and early spring. Once discovered, promptly clean up diseased and residual tissue to reduce sources of infection, strengthen ventilation and control watering; in the early stages of disease, spray with 200ppm-1000ppm streptomycin, oxytetracycline or penicillin solution, or apply it to the diseased plants, then pour the same solution onto the potting soil of the diseased plants; spray with equal-amount Bordeaux mixture or 0.40 lime sulfur mixture.

Gray mold:Caused by fungi of the genus Botrytis in the class Deuteromycetes. It mostly occurs on leaves and petioles. Lesions are initially dark green to yellow-white small spots, water-soaked, and after expansion the lesions become irregular, sunken, soft-rotted and dark brown. Under humid conditions, a soft gray-brown mold appears on the lesions, namely the conidial clusters of the pathogen, and later flower stalks and faded flowers are also covered with gray mold spots. It can cause repeated infection in greenhouses, but is most severe from February to April and from July to August. High temperature and humidity and poor ventilation all favor the occurrence of this disease. Once discovered, promptly clean up diseased plants and adjust temperature, humidity and ventilation conditions; in the early stages of disease, spray 1% equal-amount Bordeaux mixture, polyoxin at 2000 times dilution or 70% thiophanate at 1000-1500 times dilution.

Anthracnose:Caused by fungi of the genus Colletotrichum in the class Deuteromycetes. It occurs on leaves and petioles. Lesions on leaves mostly occur on the underside. The lesions are initially brown with indistinct edges, expanding outward in concentric rings, nearly round to irregular, dark brown inside with yellow-brown edges, and later gray-black granular bodies appear on the lesions. Under humid conditions, a gray-white gelatinous substance is extruded, namely the acervuli and conidia of the pathogen. Diseased leaves do not fall off after drying up. It mostly occurs from May to July. High temperature and high humidity, existing bacterial soft rot, and damage by aphids and red spider mites favor the occurrence of the disease. Once discovered, promptly remove diseased leaves and eliminate insects; in the early stages of disease, spray 60% anthracnose-formaldehyde at 500 times dilution or 70% thiophanate at 1500 times dilution.

Leaf spot:Caused by pathogens. Affected leaves develop black spots that expand, then turn light brown and dry up. Once discovered, diseased leaves should be removed early, ventilation strengthened, or equal-amount Bordeaux mixture sprayed.

Root-knot nematode disease:Caused by infection with pathogens brought about by nematodes damaging the roots. The roots develop raised nodular growths, the plant grows weakly, and the leaves wither. Once discovered, sterilize the soil with 2000-4000 times mercuric chloride water. To prevent nematodes, potting soil must be sterilized and disinfected in advance.