In recent years, the occurrence and damage caused by gray mold in greenhouse-grown courgettes have become increasingly severe. According to field surveys, this disease can significantly reduce crop yield and, in extreme cases, lead to total crop loss. The pathogen affects various plant parts, including flowers, fruits, stems, and leaves.
The infection typically starts through withered female flowers. Initially, the petals appear water-soaked or discolored, then gradually soften and rot, forming a brownish layer of mold. This leads to petal wilting and falling off. As the disease progresses, the pathogens move into young fruits, causing them to soften and develop a thick layer of gray mold. If infected tissue falls onto leaves or stems, it can trigger infections in those areas as well, resulting in large, irregular spots on the leaves. These spots often have a brown ring in the center, and under high humidity, a visible gray mold layer can be observed.
Infected stems show gray lesions, and after about a week, the stems may break entirely, leading to further damage. To manage this disease effectively, several preventive measures should be taken.
First, it's important to keep the greenhouse clean by removing infected leaves, flowers, and fruits promptly. These materials should be disposed of properly, either by burning or removing from the area. Cleaning the greenhouse film also helps improve light penetration, which promotes healthier plant growth and enhances the plant’s natural resistance to disease.
Controlling temperature and humidity is crucial. Using methods like mulching or drip irrigation can help regulate moisture levels. Watering should be done carefully to avoid excessive humidity. In the morning, maintaining higher temperatures can inhibit pathogen spore development and help evaporate dew. In the afternoon, increasing ventilation reduces humidity inside the greenhouse. At night, raising the temperature slightly can prevent condensation on the foliage.
When using 2,4-D for flower thinning, care should be taken to avoid creating wounds that could allow bacteria to enter. Adding fungicides like carbendazim to the solution during flowering can help prevent bacterial invasion. Additionally, during agricultural practices, it's essential to minimize physical damage to plants to reduce disease spread.
In chemical control, it's advisable to use pesticides sparingly. Spraying can increase humidity, so alternative methods such as aerosols or dust formulations are preferred. Rotating different types of fungicides can also help prevent the development of resistant strains of the pathogen.
By combining these cultural, environmental, and chemical strategies, growers can significantly reduce the impact of gray mold on their courgette crops.
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