Red Bark Phenomenon

Recent trips on highways along the Ohio river revealed the so-called Red Bark Phenomenon (RBP) continues on American sycamore (Platanus occidentalis). RBP appears as orangish-red to deep red staining on the bark. Vertical streaks are common making trees look like they’re oozing blood.

Last Wednesday, Jerry Frankenhoff (Urban Forester, Great Parks of Hamilton County) sent an e-mail message asking about red staining on the bark of sycamore trees. He wrote that he'd never seen anything like this before. I was shocked when I looked at his attached image. Likewise, I had never before seen the unusual reddening symptoms on sycamore or any other tree.