Causes of Disease Outbreaks in Greenhouses
- High Humidity and Poor Ventilation: Excess moisture favors fungal pathogens like Botrytis cinerea (gray mold), powdery mildew, and downy mildew.
- Warm and Moist Conditions: Create an ideal environment for bacterial wilt, damping-off, and root rots.
- Use of Contaminated Soil or Growing Media: Soil-borne pathogens (Fusarium, Pythium, Phytophthora) persist in reused soil or unsterilized substrates.
- Infected Planting Material: Transplants, cuttings, or seeds may harbor fungal spores, bacteria, or latent viruses.
- Poor Sanitation: Crop debris left inside the greenhouse serves as a reservoir for pathogens and insects.
- Overhead Irrigation and Excess Moisture: Prolongs leaf wetness, favoring foliar diseases like downy mildew and bacterial leaf spots.
- Vector Transmission: Insects like whiteflies, thrips, and aphids act as carriers of viruses (e.g., Tomato Yellow Leaf Curl Virus, Cucumber Mosaic Virus).
- Continuous Cropping: Lack of crop rotation leads to accumulation of soil-borne pathogens year after year.