Powdery Mildew on New Roses: Copper Treatment & Fertilizing Timing

Mark (UK south coast) had powdery mildew on new roses that also had minor black spot. He had neem oil and wettable sulfur. Jay's protocol:

Treatment Sequence

1. Use copper fungicide first to eradicate active mildew.
2. Do NOT mix copper with neem oil—phytotoxicity risk.
3. After control, use neem oil preventively for both mildew and black spot.
4. Watch temperatures: Neem not recommended over 85°F (29°C).

Fertilizing Timing

• Apply fertilizer after last frost for spring bloom fuel.
• Don't fertilize newly planted roses until established.
• Mark's plan (composted manure + bone meal in Jan/Feb, Vitax Q4 after first flush) is sound.

Jay's note: "This summer is going to be brutal everywhere I believe."