What’s Up With The White Coating on Tulip Leaves?

Editor’s note: This article was initially published in The Daily Gazette, Swarthmore’s online, daily newspaper founded in Fall 1996. As of Fall 2018, the DG has merged with The Phoenix. See the about page to read more about the DG.

Powdery mildew on oak leaves in Maryland. Photo by Jeff Kubina, released under Creative Commons.

A reader noticed that some of the leaves falling near Kohlberg and Trotter had a strange white substance on them. According to Josh Coceano, an intern at the Scott Arboretum, the strange substance is powdery mildew, which “grows on stressed or dead plants.”

“In this case, the fallen tulip tree (Liriodendron) leaves are serving as a host for the disease. It is not harmful, nor fatal. It has most likely been on the leaves all growing season and has just started to grow in response to the cool temperatures and precipitation,” Coceano wrote.

He added, “Thanks for keeping a watchful eye on the arboretum.”

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