Cucumber blight is a serious soil-borne disease that commonly affects autumn cucumbers, especially in northern regions. This disease can lead to widespread plant death and significantly reduce yields by approximately 30%, making it one of the most damaging diseases for cucumber crops during the fall season.
The disease can occur throughout the entire growing period in summer and autumn. In the seedling stage, tender stems become waterlogged, soft, and eventually collapse without falling over. Adult plants are also vulnerable, with infected stems showing signs of water-soaked lesions. The upper parts of the plants may wilt, and large round spots appear on the leaves. Infected fruits develop rot, sag, and emit an unpleasant odor, while white mold appears on the surface. This leads to malformed cucumbers and premature dropping of young fruits.
The bacteria responsible for this disease spread through irrigation water, field activities, and contaminated tools. High humidity, poor drainage, and low-lying areas create ideal conditions for the disease to thrive.
To prevent cucumber blight, crop rotation is essential. It is recommended to avoid planting cucumbers in the same area consecutively or after other vegetables. Rotating with legumes for 2–3 years can help reduce the buildup of pathogens in the soil. Using resistant varieties is one of the most effective strategies. Seeds can be treated with warm water or grown into disease-free seedlings to enhance resistance. Grafting cucumber onto black-seeded pumpkin rootstocks has also proven effective in preventing the disease.
Field management plays a crucial role in disease control. Raised beds should be used, with a height of 15–20 cm, a width of 30–40 cm, and spacing between wide and narrow ridges of 80–90 cm and 40–50 cm, respectively. Plant density should be around 3,800–4,000 plants per mu. Diseased plants and leaves should be removed promptly, and all debris, rhizomes, and weeds should be cleared after harvest to minimize infection sources. Drip or under-membrane irrigation is preferred to prevent waterlogging. Watering should be minimized during the early stages of the disease to limit its spread. Mulching helps prevent bacteria from reaching the stems, leaves, and fruits.
Proper fertilization is important—excessive nitrogen should be avoided. When the disease is detected, a 58% mancozeb wettable powder at a 500-fold dilution can be applied. Spraying should be done every 5–7 days for three applications, and the last spray should be completed at least 10 days before harvest to ensure safe harvesting.
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