Lace Tomato Blight, also known as Late Blight, is a fungal disease that can be devastating to tomato and potato crops. This disease is caused by the pathogen Phytophthora infestans and thrives in warm, humid conditions, making it a common problem in many gardening regions. Lace Tomato Blight is highly contagious and can spread rapidly through a garden, infecting large areas of crops in a short period of time.
Symptoms
- Small, water-soaked spots on leaves, which quickly enlarge and become brown or black.
- The spots may have a target-like appearance with a dark brown or black center and a lighter brown border.
- Rapid wilting and yellowing of leaves, starting from the bottom of the plant and working upward.
- Soft, water-soaked lesions on fruit, which enlarge and become sunken. The fruit may become distorted and develop a leathery texture.
- Shriveling and decay of fruit, which may become covered in a white, cottony growth.
- A white, cottony growth may also be visible on the underside of infected leaves and stems.
- In severe cases, the entire plant may wilt and die within a few days.
What is Lace Tomato Blight
- Water-soaked, dark green to brown spots on leaves and stems, which rapidly enlarge and become sunken.
- The spots may be circular in shape and have a target-like appearance, with a dark brown or black center and a lighter brown border.
- The spots may also have a raised, papery texture and may be surrounded by a yellow halo.
- White, cottony growth on the underside of infected leaves and stems, which may spread to cover the entire plant. The growth may be dense and thick, and may resemble mold.
- Shriveled, decayed fruit with dark brown or black lesions, which may be surrounded by a lighter brown ring. The fruit may become distorted and develop a leathery texture.
- Rapid wilting and yellowing of leaves, which may start from the bottom of the plant and work upward.
Treating a Lace Tomato Blight Infestation
It may be necessary to use a combination of control methods to effectively manage Lace Tomato Blight in a garden. Regularly monitoring your plants for symptoms and taking action quickly can help to reduce the spread of the disease and prevent significant damage to your crops.
Cultural Control
- Crop rotation: Planting tomatoes or potatoes in a different location from the previous year can reduce the buildup of pathogen in the soil. This method helps to reduce the risk of infection by breaking the cycle of the pathogen in the soil and reducing its ability to infect new plants.
- Adequate spacing: Maintaining adequate spacing between plants can help to reduce the spread of the disease by improving air flow and reducing humidity levels. This helps to reduce the risk of infection by reducing the opportunities for the pathogen to spread from plant to plant.
- Avoid overhead irrigation: Watering the plants from below, such as using a drip irrigation system, can help to reduce the spread of the disease by keeping leaves and fruit dry. Overhead irrigation can increase the humidity levels on the plant and provide a moist environment for the pathogen to thrive.
- Proper pruning: Regularly removing infected leaves and stems can help to reduce the spread of the disease and improve air flow within the plant. This can help to reduce the risk of infection by reducing the opportunities for the pathogen to spread from leaf to leaf or from stem to stem.
Chemical Control
- Fungicides: Applying fungicides specifically designed to control Lace Tomato Blight can help to reduce the spread of the disease and prevent new infections. Fungicides work by killing or inhibiting the growth of the pathogen and can be applied as a preventative measure or at the first sign of infection.
- Copper-based fungicides: Copper-based fungicides can help to prevent the spread of Lace Tomato Blight by creating a protective barrier on the leaves and stems of the plant. This can help to reduce the risk of infection by reducing the opportunities for the pathogen to penetrate the plant.
- Systemic fungicides: Systemic fungicides can be absorbed by the plant and provide protection from within. This type of fungicide can help to protect the plant from infection, even if the pathogen is present in the soil or on the plant surface.
- Timing: It is important to apply fungicides at the first sign of infection and to follow the manufacturer’s instructions for application rates and frequency. Fungicides are most effective when used preventatively or at the first sign of infection, before the pathogen has had a chance to spread.
Physical Control
- Sanitation: Regularly removing infected plant parts and cleaning up plant debris can help to reduce the buildup of the pathogen in the soil. This can help to reduce the risk of infection by reducing the opportunities for the pathogen to overwinter in the soil and infect new plants.
- Covering plants: Covering tomato plants with a physical barrier, such as a row cover, can help to prevent the spread of Lace Tomato Blight by reducing humidity levels and improving air flow. This can help to reduce the risk of infection by creating a microclimate around the plant that is less conducive to the growth of the pathogen.
- Pruning: Regularly removing infected leaves and stems can help to reduce the spread of the disease and improve air flow within the plant. This can help to reduce the risk of infection by reducing the opportunities for the pathogen to spread from leaf to leaf or from stem to stem.
Biological Control
- Beneficial microorganisms: Applying beneficial microorganisms, such as Bacillus subtilis, can help to control Lace Tomato Blight by competing with the pathogen for resources and reducing its ability to infect the plant. This can help to reduce the risk of infection by reducing the opportunities for the pathogen to thrive.
- Biopesticides: Biopesticides, such as extracts from garlic or chrysanthemum, can help to control Lace Tomato Blight by disrupting the growth and reproduction of the pathogen. This type of control method works by using natural materials to control the pathogen, rather than relying on chemical fungicides.