Fertilization Methods for Edible Mushrooms and the Occurrence and Control of Soft Rot in Clivia

Clivia is a perennial evergreen herbaceous flower of the genus Clivia in the Amaryllidaceae family. Since it was introduced to China from Japan in 1932, it has been commonly cultivated in various regions. However, due to the occurrence and damage of soft rot in Clivia, entire plants often die, causing significant losses.

I. Symptoms

The disease mainly affects the pseudobulb and leaves of Clivia. At the base of the stem, small water-soaked spots first appear, gradually expanding into light brown patches that spread to the pseudobulb, causing the tissue to rot and become soft and foul-smelling. The lesions at the stem base can also spread along the leaf veins toward the leaves. In the early stage, the leaves show water-soaked spots, which then rapidly expand and become rotten and semi-transparent, with a yellow halo around the lesions and a broad band surrounding the halo. In severe cases, the entire leaf rots and disintegrates into wet rot.

The pathogen of this disease is bacteria, mainly Erwinia chrysanthemi and Erwinia carotovora subsp. atroseptica of the genus Erwinia.

II. Disease Occurrence Patterns

The pathogenic bacteria overwinter in soil or in diseased plant residues. The disease can occur from June to November, but mostly occurs during the hot and humid summer period. Poor ventilation favors the spread and development of the disease. The bacteria can survive in soil for several months, and contaminated soil is an important source of infection. Therefore, incomplete soil disinfection can easily lead to the occurrence of this disease. In addition, it can also be transmitted through water flow, insects, contact and friction between diseased leaves and healthy leaves, or through handling tools. The bacteria invade the plant through wounds and can cause disease within a few days, and can repeatedly infect the plant multiple times during the growing season. In summer, if the stem core of Clivia is exposed to rain or if water is accidentally poured into the stem core during watering, the disease can be triggered. In addition to infecting Clivia, this pathogen can also cause disease in chrysanthemums, carnations, dahlias, begonias, and kalanchoes.

III. Control Methods

1. Soil disinfection: To prevent soft rot early, disinfect the potting soil before transplanting. The soil can be disinfected with 0.5%-1% formalin at about 10g per square meter; it can also be disinfected with chloropicrin at 60-120g per square meter or 70% quintozene at 8-10g per square meter.

Used flower pots and contaminated tools should also be washed and disinfected with 1% copper sulfate before reuse. Do not water excessively during normal care to avoid overly wet potting soil.

2. Agricultural control: Promptly prune or pull out diseased plants and destroy them; avoid bruising plants during planting and transplanting to prevent wound infection; pay attention to drainage during disease outbreaks to keep roots and stems dry and prevent rot of roots, rhizomes, and bulbs.

3. Chemical control: After disease onset, spraying agricultural streptomycin at 1000 times dilution or Bordeaux mixture at 150-200 times dilution about once a month can control the spread of the disease. At the same time, timely control of pests is necessary to reduce wounds and lower the disease incidence rate.