Long spots on melons can be caused by several factors, and understanding these issues is crucial for effective prevention. One of the main causes is delayed ventilation, which leads to high temperature and humidity inside the greenhouse. Once the covering is removed, moisture condenses on the melon surface as the temperature rises, creating an environment that promotes green spots, especially when ventilation is done under high-temperature conditions.
Another common cause is excessive planting density. Some farmers increase the number of plants per acre in an attempt to boost early yields. However, this results in dense foliage that restricts air circulation and light penetration, which can lead to the formation of green spots on the fruit.
Improper timing of pesticide application is also a contributing factor. When pesticides are applied during high temperatures, the melon surface may absorb the chemicals more quickly, leading to damage and green spots. Additionally, using a higher-than-recommended concentration of pesticides can directly harm the melon's surface, causing discoloration and other issues.
To prevent these problems, proper management practices are essential. First, ensure reasonable ventilation. After removing the cover in the morning, start by opening the air vents slightly, but avoid sudden temperature drops. As the internal temperature rises gradually, increase the vent size to allow moisture on the melon surface to evaporate. The ideal temperature range should be maintained between 28°C and 30°C. Even on cloudy days, short periods of ventilation are necessary to prevent humidity buildup.
Second, maintain an appropriate planting density. It’s generally recommended to keep the plant population between 2,500 and 2,800 per acre. Grafted melons typically require lower density, while non-grafted ones can tolerate slightly higher numbers.
Third, apply pesticides at the right time. It’s best to do so during the sunny hours between 9 a.m. and 10 a.m., or after 2 p.m. in the afternoon. Before applying any treatment, make sure there are no water droplets on the melon surface, as this can increase the risk of chemical burn.
Finally, always follow the recommended concentration guidelines when preparing pesticides. Using too low a concentration may not effectively control diseases, while too high a concentration can damage the fruit. Always read and follow the manufacturer’s instructions carefully.
By implementing these measures, farmers can significantly reduce the occurrence of green spots and improve the quality and yield of their melon crops.
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