Managing Black Spot on Roses: Prevention and Control Strategies

Managing Black Spot on Roses: Prevention and Control Strategies

Black spot cannot be cured, only controlled. The fungus has at least eight strains, and roses vary in susceptibility. Red and orange-red varieties are most prone; mauves and yellows less so. Start with healthy, nursery-grown plants, provide good water and fertilizer, and choose disease-resistant varieties that can lose 60% of leaves without losing vigor.

Best Preventive Spray

Apply a sulfur and dormant oil spray in late fall and early spring, following package directions for roses.