Diseases and Management of Crops under Protected Cultivation

(Diseases and Management of Crops under Protected Cultivation)
• Common diseases of greenhouse tomato
1. Gray mold
2. Leaf mold
3. Powdery mildew
4. Tomato spotted wilt virus
1. Gray mold
• Caused by the fungus Botrytis cinerea.
• A light-gray fuzzy growth that appears on stems and leaves.
• Soft rot of the stem end of the fruit can also occur.
• Most severe in greenhouses with moderate temperatures, high humidity, and stagnant air.
Management
• Increasing ventilation and air circulation to reduce humidity levels can be helpful, as well as
timely fungicide applications.
2. Leaf mold
• Caused by the fungus Fulvia fulva, in humid greenhouses with poor air circulation.
• Appears on lower leaves as yellow spots on the upper surface and fuzzy masses of buffcolored
spores on the underside.
• These leaves drop prematurely as the disease progresses upward on the plant.
Management
• Lowering greenhouse humidity, planting resistant varieties, and applying fungicide promptly
can be helpful in leaf mold management.
3. Powdery mildew
• Caused by the fungus Oidium neolycopersici
• Common in humid greenhouses with poor air movement.
• White patches on the upper surface of leaves, defoliation as the spots develop into brown
lesions.
Management
• Increase air circulation and spacing between plants
• Fungicide sprays also can be effective if used when symptoms are first noticed.
4. Tomato Spotted Wilt Virus
• The virus is spread primarily by thrips, particularly the western flower thrips.
• Leaves get blackish-brown circular spots, or tan spots bordered by a black margin.
• Fruit gets orange to yellow spots surrounded by a green margin.
Management
• Control the virus is by controlling the thrips vector through insecticides.
• Do weed control to minimize the population of thrips and virus.
Harvest and storage of tomatoes
• Harvest greenhouse tomatoes every other day early in the morning when greenhouse
- 89 -