Tomato blight is a fungal growth that affects the leaves and fruit of the tomato and potato plant. It generally begins on the leaves. While difficult to control once it reaches the fruit, there are some steps to prevent its spread.
Rotate the crops
Tomato blight is most common when plants grow in the same location several years in a row. Move the plants to the opposite side of the garden to allow any fungus to die out naturally.
Provide space for growth
Space the tomatoes 3 feet apart when planting. Use stakes or cages to hold the plants off the ground to allow for air circulation.
Remove affected growth from the garden
Watch plants closely for signs of a problem. Remove any wilted leaves as soon as you notice them. If blight spreads to the fruit, remove it from the plant. Dispose of any diseased plant material away from the garden. If the entire plant is affected, pull the plant and place it in a plastic bag for disposal. Don't compost any plants or plant material affected by blight.
Apply an antifungal spray
Options for antifungal sprays include commercially prepared sprays, baking soda dissolved in water and uncoated aspirin in water.
Stop overhead irrigation
The fungus is more likely to affect plants that are wet from overhead irrigation. Use drip irrigation to protect the plants and keep foliage dry.