Black spot is the most common foliar disease of roses in the United States. Per Cornell Cooperative Extension's rose disease guide, Diplocarpon rosae is present in nearly every region where roses are grown, and in eastern gardens with humid summers it appears reliably every season on susceptible varieties. It does not kill established roses outright, but it defoliates them repeatedly through the season, weakening the plant and reducing bloom.
I don't grow roses in my Long Island garden — deer pressure here makes most hybrid teas a write-off without serious fencing — but this guide draws from the same extension sources I rely on for everything else.
This article contains affiliate links. As an Amazon Associate, we earn from qualifying purchases - at no extra cost to you. We only recommend products we have personally tested or that are the universal first recommendation from university Extension publications. See our full disclosure.
Get the seasonal care notes — no upsell, unsubscribe any time.
One email per month from Thomas: what to plant, what to prune, what's about to break. Cited the same way as the guides.
Free. No spam. Same author as the guide you just read.
Got it — check your inbox to confirm. Welcome.
Stop fungal disease early
Neem oil suppresses powdery mildew, black spot, and rust when sprayed at first sign. Cheaper than copper-based fungicides and safe on veg. Read our full pick.
