Photo of the Week – March 17, 2016

You’ve probably seen them – funny-looking brown balls stuck to eastern red cedar trees.  Sometimes, the  balls have long gooey orange tentacles hanging from them.  Do you know the story behind them?


Cedar-apple rust is a fascinating organism that uses two different hosts to help it complete its life cycle.  Galls that form on eastern red cedar trees eventually release spores, some of which make their way to leaves of apple or crabapple trees.  On those leaves, they stimulate formation of yellow lesions that eventually mature and create more spores that then need to make their way back to another cedar tree to complete the cycle.  The lesions on the leaves can be harmful to the apple trees (including the one in my yard) but I’m not sure there’s any big impact on cedars.

You can read much more about this at the Missouri Botanical Garden’s website.

I found the above gall at our family prairie last month.  And yes, I did cut the cedar tree down after I photographed the gall (see photo evidence below).


This entry was posted in Prairie Natural History, Prairie Photography and tagged , , , by Chris Helzer. Bookmark the permalink.

About Chris Helzer

Chris Helzer is the Director of Science for The Nature Conservancy in Nebraska. His main role is to evaluate and capture lessons from the Conservancy’s land management and restoration work and then share those lessons with other landowners – both private and public. In addition, Chris works to raise awareness about the importance of prairies and their conservation through his writing, photography, and presentations to various groups. Chris is also the author of "The Ecology and Management of Prairies in the Central United States", published by the University of Iowa Press. He lives in Aurora, Nebraska with his wife Kim and their children.

5 thoughts on “Photo of the Week – March 17, 2016

  1. Hey Chris, really enjoy your blog even though I am not an ecologist by training. Just curious why you cut the tree. Was it to prevent the spread of cedar-apple rust? Is this not a natural host-parasite interaction (i.e. has the rust been imported from somewhere)? Thanks.

  2. Of course, I didn’t think about this when I plant my 7 apple trees. It’s a good way to see which variety is CR resistant.


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