Vibrio sclerotiorum stalk rot
2025-08-07 03:13:17
Symptoms
The disease primarily affects the Yangtze River basin. It typically appears at the base of the stem near the ground. The affected area turns from light green to pale white, losing its natural color. A thick layer of white mycelium develops on the diseased part, and the filaments spread both upward and downward for a short distance. As the infection progresses, the mycelium spreads into the surrounding soil, gradually changing from yellow to brown. In the later stages, dark brown seedlings grow on the decayed tissue, covering the entire infected surface. The mycelium can also develop within the rotted root tissues. Large numbers of black sclerotia are found in the infected plant parts, and severely affected plants eventually die.Pathogen
The pathogen is *Sclerotinia trifoliorum* Erikss., which belongs to the genus *Aspergillus* subfungus. The structure includes a sclerotium that is tuber-like in shape. Sclerotia are spherical to elliptical, black in color, with a rough surface, measuring 3–5 mm in size. The apical portion is funnel-shaped or disc-shaped, with a light reddish-brown color. The sac-stick is rod-shaped to cylindrical, ranging in size from 147–2349 µm in length and 3–16.5 µm in width. Ascospores are oval to elliptical, measuring 8–20 µm by 5–13 µm. Sexual spores are spherical, approximately 2–3 µm in diameter.Transmission Routes and Conditions
The pathogen mainly overwinters in the form of sclerotia in the soil. In the following year, these sclerotia germinate, producing ascus disks and releasing ascospores, which serve as the initial source of infection. However, the ascospores cannot directly infect healthy broad bean plants. Instead, they produce a large amount of hyphae in the soil beneath the host's stem base. These hyphae grow and expand along the surface of the host, weakening its resistance and waiting for the right moment to invade. When the temperature is between 15–18°C and humidity is high, numerous appositional discs are formed, allowing the ascospores to penetrate the plant. The optimal temperature for disease development is 17–22°C, and the disease usually begins in February to April, with rapid expansion occurring in April and May. The disease is more likely to occur in fields where crops like Ziyunying (a local crop) are grown nearby or in rotation systems. Overly dense planting and poor drainage between rows can lead to high moisture levels, increasing the incidence of the disease.Control Methods
(1) Implement crop rotation with grass crops for 2–3 years. Regularly till the soil and avoid planting seeds too densely. Make sure to remove sclerotia from the field and promptly destroy or bury infected plants after harvest. (2) Apply enzyme compost or fully decomposed organic fertilizer, use formula fertilization techniques, and avoid excessive or partial application of nitrogen fertilizer. Increase the use of phosphorus, potassium, and lime to improve soil health. (3) Strengthen field management by ensuring proper drainage after rain to prevent excessive moisture buildup in the field. (4) Apply 36% Thiophanate Methyl Suspension diluted 500 times, or 40% Sulfur Suspension diluted 600 times, 50% Benomyl WP diluted 1500 times, or 60% Anti-mold Agent No. 2 diluted 800 times. Spray 50–60 liters per 667 square meters, repeating every 10 days for 2–3 applications to effectively control the disease.Gummy Jelly Candy,Yummy Gummy Candy,Gummy Heart Candy,Sugar Free Gummy Candy
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