October 18, 2025
Cotton cotton red rot
Cotton crops across China are affected by a range of diseases, particularly in the Yangtze River Valley, Yellow River Basin, and Liao River regions. The disease can affect seedlings and bolls, causing significant damage. Infected young shoots may be damaged before emergence, with buds turning reddish-brown. Once emerged, the roots of infected seedlings show yellowing, followed by dark brown discoloration and rot. The stems of young plants become dark brown, with yellow streaks near the base, eventually leading to rot. The roots and stems may swell, while the cotyledons and true leaves develop irregular gray or pinkish spots. A pink mold layer, consisting of conidia from the pathogen, often appears on the surface.
Early sowing under low temperature and rainy conditions can lead to severe root rot, resulting in plant death. In adult plants, infected stems show brown scars, cortical erosion, and yellow-brown discoloration in the xylem. Bolls may also suffer from red rot, further reducing yield and quality.
The pathogen responsible is primarily *Fusarium moniliforme* var. *intermedium*, along with other species such as *F. semitectum*, *F. avenaceum*, *F. graminearum*, and *F. oxysporum*. On PDA medium, *F. moniliforme* var. *intermedium* produces a velvety, pink, or pale purple appearance. It forms both single and double bottle-shaped conidia, with small, oval or narrowly melon-shaped conidia measuring 5.3–10.8 × 2.74 μm.
The disease spreads through overwintering pathogens in crop residues or soil. Conidia and mycelium serve as primary sources for the next growing season. Seeds can also carry latent mycelium, which infects seedlings after planting. The fungus thrives during the growing season and spreads via wind, rain, insects, and wounds on cotton bolls. The pathogen grows well between 3°C and 37°C, with optimal growth at 20–24°C. High humidity and prolonged rainfall increase the risk of outbreaks, especially during the seedling stage. Low temperatures combined with high humidity make the disease more severe, while dry conditions reduce its occurrence.
To manage the disease, farmers should use healthy, disease-free seeds. Field sanitation is crucial—removing dead branches, fallen leaves, and rotten bolls and burning them reduces initial infection sources. Proper sowing practices, along with balanced fertilization, promote strong seedling growth and improve resistance. Timely pest control helps avoid mechanical injuries that allow pathogens to enter. Seed treatment with 50% carbendazim WP (1 kg per 100 kg of seeds) is recommended. During the boll stage, spraying Bordeaux mixture (1:1:200), 50% thiophanate-methyl (800 times), 50% carbendazim (1000 times), 50% benomyl (1500 times), or 65% TB wettable powder (1500 times) every 7–10 days for 2–3 applications can help prevent and control the disease effectively.
Dc 4.5V Co Alarm,Co Detector,Carbon Monoxide Alarm,Carbon Monoxide Detector
Guangdong Isafenest Co.,Ltd. , https://www.isfenest.com