In the greenhouse, humidity levels were quite high, which led to an increased occurrence of vegetable diseases. Among these, gray mold, bacterial blight, downy mildew, and anthracnose were the most prevalent. Effectively managing these key diseases was essential for overall disease control in the greenhouse.
Gray mold, caused by *Botrytis cinerea*, is one of the most common and damaging diseases, particularly affecting eggplants, tomatoes, peppers, cucumbers, and kidney beans. The disease tends to be more severe before and after flowering. It thrives under low temperatures (10–15°C), rainy weather, and high humidity. To prevent and manage it, proper drainage and timely ventilation are crucial. At the early stage of infection, several fungicides can be used, such as 50% iprodione, 25% mancozeb, 50% chlorothalonil, 25% polyram, 10% difenoconazole, or 20% pyrimethanil. Additionally, smoke agents like shi gram, fast-king, and chlorothalonil mixed with wood chips (0.3 kg per 30 cubic meters) can be effective when burned.
Another major concern is *M. blight*, which affects not only eggplants but also cucumbers, wax gourds, and legumes. Eggplants are especially vulnerable during their fruiting period. The disease causes round, water-soaked spots on the fruit that turn yellow-brown and sunken over time, eventually leading to black rot and fruit drop. During periods of continuous rain, it becomes a critical focus for disease prevention. Fungicides such as 78% mancozeb, 20% carbendazim, 72% mancozeb (Kelu), 64% oxadixyl, 68.7% cyprodinil + fludioxonil, 50% dimethomorph, 58% methoxyfen, and 25% metalaxyl are recommended.
Downy mildew is a serious threat to cucumbers, primarily attacking the leaves. Initially, small water-soaked, light green spots appear, which quickly turn brown when exposed to heat. The disease spreads rapidly in high humidity and warm conditions, typically peaking in mid-to-late May, which coincides with the peak fruiting season. Preventive measures should begin in early May, before the hot and humid conditions set in. Suitable fungicides include 72% Kelu, 58% Ledomil, 70% chlorothalonil, and 72% Prokary (Perkinam). Chlorothalonil smoke agents are also effective during the seeding period.
Anthracnose is a significant disease affecting chili peppers, as well as eggplants, tomatoes, melons, and legumes. It is commonly known as defoliation, with symptoms varying based on the type—black spot, red spot, or orange-red dots. High temperatures, heavy rainfall, poor drainage, dense planting, improper fertilization, excessive nitrogen, and poor air circulation all contribute to its spread. Prevention and control should start in early May, with continued efforts from June to August. Recommended treatments include 75% chlorothalonil, 87% mancozeb, 50% thiophanate-methyl, and 64% oxadixyl.
By implementing these targeted strategies, growers can significantly reduce the impact of these common greenhouse diseases and improve crop health and yield.
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