Notes on hydration for edible fungi and two common diseases of Clivia

Bacterial soft rot

Symptoms: The disease mainly occurs on leaves and stems. On leaves, it mostly starts at the leaf base; the diseased part is dull, dark green on both sides, water-soaked, and irregular in shape. In severe cases, it develops upward along the leaf veins, causing the diseased leaves to rot, soften, and droop.

Pathogen and disease characteristics

The pathogen belongs to the genus Erwinia. The bacterial cells are single, rod-shaped, with multiple peritrichous flagella, have a capsule, and are Gram-negative. The optimum growth temperature for the pathogen is 28°C. The pathogen can produce acid and gas from the fermentation of glucose, sucrose, xylose, fructose, and sorbitol. It survives on diseased plant residues in the soil and is spread by rain, irrigation water, insects, and human handling, invading the host through wounds. Under conditions of high temperature and high humidity with poor ventilation, the disease is severe. It occurs more frequently from June to September.

Control methods

① During horticultural operations, avoid causing wounds as much as possible, promote robust plant growth, and control pests to reduce insect wounds.

② Keep the room frequently ventilated to reduce humidity.

③ In the early stage of the disease, streptomycin or oxytetracycline at 200 to 1000 ppm can be sprayed on the diseased parts of the plant.

Leaf spot disease

Symptoms: It mainly damages leaves. Small brown spots first appear on the leaves, then expand and form irregular large spots, light brown to grayish brown, with slightly raised edges. Later, small black dots also appear on the lesions.

Pathogen and occurrence characteristics

The pathogen's pycnidia are flattened spherical and dark brown, while the conidia are oval and single-celled. The pathogen survives in diseased plant residues and, like Clivia bacterial soft rot, invades through plant wounds. In greenhouses, it can occur year-round. Poor ventilation, too little light, and excessively high humidity in the greenhouse are unfavorable for plant growth, thereby reducing disease resistance: if water is poured onto the leaves when watering, it favors the growth and development of the pathogen, making infection very likely. It is more severe from July to November.

Control methods

① Prune off diseased leaves and clean the leaf surface at any time to reduce opportunities for pathogen infection.

② When repotting in spring, apply sufficient base fertilizer and place the plant in a shade shed. During the growing period, apply more topdressing so that the soil remains moist and ventilation is good. Generally, no fertilizer is applied in summer.

③ When the disease occurs, spray with 70% thiophanate-methyl at 1000 times dilution.