Septoria Leaf Spot & Powdery Mildew in Kansas Garden

Your wet-season garden disaster: Septoria leaf spot (tomatoes) and powdery mildew (cucurbits). The elm's black dust is unrelated (aphid honeydew + sooty mold).

Septoria Management (Tomatoes)

• Rotate crops (3-year non-solanaceous).
• Resistant varieties ('Iron Lady', 'Mountain Magic', 'Defiant').
• Space widely (3+ ft), stake, prune suckers.
• Mulch (plastic or straw)—prevents soil splash.
• Drip irrigation only—no wet leaves.
• Chlorothalonil preventive at first flower, repeat 7–10 days.

Powdery Mildew (Squash/Cukes)

• Resistant varieties (PM-tolerant cultivars).
• Full sun, wide spacing.
• Sulfur or potassium bicarbonate (Kaligreen) at first sign.
• Remove infected leaves promptly.

Soil Treatment?

NO—copper fungicide on soil wastes money. Spores overwinter on plant debris, not in soil. Remove ALL dead plants now. Burn, bury, or trash.

Elm Black Dust

Aphid honeydew + sooty mold. Not your garden's problem.

Clean start next year: sanitation, resistant varieties, drip irrigation, preventive sprays.