I took this picture in April .. but only recently figured out what it was. When looking up something else I ran across a photo of Eastern Gall Rust (Cronartium quercuum). It's similar to the Cedar Apple Rust that I wrote about last year. They are both heteroecious, which means that they require two unrelated hosts to complete the life cycle.
I learned that $10 word from the Rust page on James Worrall's excellent Forest Pathology site, where you can also learn about cankers and wilts and so many other problems that you'll be amazed that trees can survive at all.
According to one site, the portion of the tree beyond the gall normally dies, which I suppose explains why I haven't noticed this gall since the spring I took this picture.
No comments:
Post a Comment