Control Plant Diseases Before They Destroy Your Plants

Disease Causes

• Leaf/stem: Bacteria, fungi, viruses. Bacteria steal nutrients. Fungi (most common) parasitize plants, spread via spores (wind/water). Viruses invade tissue, spread by aphids, leafhoppers, thrips, human propagation.
• Soilborne: Fungi (damping off, oak root fungus, water molds, verticillium wilt).
• Environmental: Air pollution, light extremes, climate mismatch (too hot/cold/dry/wet).

Common Leaf/Stem Diseases

1. Anthracnose – brown blotches, premature leaf drop
2. Black Spot – circular black spots with yellow halos
3. Dutch Elm Disease – spreads via root grafts
4. Fireblight – enters via water splash, insects, wounds
5. Leaf Spot – colored spots, defoliation
6. Peach Leaf Curl – distorted leaves, white spores
7. Powdery Mildew – gray/white powdery patches
8. Scab – dark fungal growth on foliage
9. Rust – host-specific (rose rust ≠ hollyhock rust)

Soilborne Diseases

1. Damping Off – seedling collapse at soil line
2. Oak Root Fungus – decays roots, girdles stem
3. Root Rots/Water Molds – from overwatering/warm soil
4. Verticillium Wilt – plugs vascular tissue, one-sided wilt

Control Strategies

Prevention first: Choose resistant varieties, optimal planting conditions.

Products:

• Preventives: Stop disease before establishment (ineffective once active).
• Eradicants: Control established disease.

Read labels carefully. Apply only to listed plants.

Common Fungicides & Uses

• Sulfur – powdery mildew, scab, rust (oldest, safest)
• Lime Sulfur – mites, scale, thrips; leaf spots, peach leaf curl, mildew
• Captan – damping off, leaf spots, fungal diseases
• Triforine – powdery mildew, rust, black spot
• Copper – fireblight, peach leaf curl, shot hole
• Chlorothalonil – lawns, fruits, vegetables, ornamentals
• Triadimefon – azalea petal blight, mildew, rust, lawn diseases