The most common fungal infections, blight, powdery mildew, and black spot, can be devastating in your vegetable garden, flower garden, or fruit trees. Here’s a primer on symptoms and prevention.
Consistently wet, humid, or damp weather creates a perfect environment for fungal infections of plants. Fungi spores grow rapidly in persistent moisture and at the very least create stress on the plant, leaving them vulnerable to secondary infections. Early prevention is the best defense, because once you actually spot symptoms, it’s usually a losing battle. Here’s what you should look for:
Black Spot: Affects roses and fruit trees and is very common in apples and pears. As its name implies, the disease starts as small black spots on the tree’s leaves which grow larger as the season progresses. Black Spot frequently spreads to the fruit bud as well and will show on the fruit as it matures, resulting in a fruit neither pleasing to the eye nor the taste buds. Treatment: any solution which contains copper sulfate or copper hydroxide, sold under various brand names
Tomato Blight: According to Rodale’s Pest And Disease Problem Solver: “Leaf spots are the first symptom of early blight. The spots are brown with a concentric target pattern…they usually appear on oldest leaves first. Spots enlarge and run together…Dark, sunken lesions appear on the stems, often starting near the soil in young plants.” The leaves yellow and fall off, lowest ones first and the fruit becomes discolored.
To avoid Tomato Blight, follow these guidelines:
- Plant heirloom varieties: These tomatoes are decades old or more, and have survived many diseases and weather extremes. They may not be immune to blight, but they stand a better chance of surviving it.
- Use mulch under your seedlings. Mulch suppresses fungal spores which may have overwintered in your soil
- Plant varieties well adapted to your area.
- Plant varieties resistant to blight. These would be marked as LB (late blight resistance) and AB (Alternaria/Early Blight resistance) on the plant tags at the nursery.
- Leave more space than usual between your seedlings. Air flow is essential for helping plants to dry quickly after a rain storm. If the plants spend less time wet, they’ll be less susceptible to blight infection.
- Plant your tomato seedlings on the opposite side of the garden from where blight occurred previously.
Treatment: same as Black Spot above.
If you suspect any symptoms of powdery mildew, black spot or tomato blight, treat your plants immediately. The earlier you treat the plant, the more likely you’ll get the fungus under control. It’s always a good idea to treat at the first report of symptoms in your area, even if you haven’t yet seen any symptoms yet in your own garden.