Sunflower Diseases: 9 Common Ones

Sunflowers face 30+ diseases, but 9 are most common. The top 6 yield-robbers:

Major Diseases

1. Downy mildew (Plasmopara halstedii)
2. Rust (Puccinia helianthi)
3. Sclerotinia (white mold, stalk/head rot)
4. Verticillium wilt
5. Phoma (black stem)
6. Alternaria leaf spot

Minor/Occasional

• Septoria leaf spot
• Powdery mildew
• Rhizopus head rot
• Charcoal stem rot

Management

• Resistant hybrids (rust, Verticillium).
• Seed treatment for downy mildew zones.
• Crop rotation (3–4 years non-host).
• Fungicides rarely economic except for new rust races.

Your Frost Experiment

"Frosting" = ? Try it! Science = test + record. Frost likely kills seedlings; mature plants may tolerate light frost. Good luck!