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Cedar Trees + Apple Trees = A VERY Weird Disease

Question. Is there any natural way to control cedar apple rust short of chopping down the trees? My junipers are full of the galls and my apple trees have developed the spots. The apples are in a nice breezy field, but, alas, surrounded by cedars. Help!

    ---Laura in Orange County, Virginia

Hello Mike! A friend in upper Bucks County, PA just emailed me these pictures of growths on his cedars. After a little Internet searching, I found pictures of cedar-apple rust disease that match. What does he need to do? Thank you,

    --Janet, also in Bucks County, PA

Answer. You forget how dramatic Nature can be until images like this remind you who the ultimate set decorator is! While the poor apple trees just get small yellowish spots on their leaves and disfigured fruits, the "gelatinous orange masses" that appear on cedars as their part of this weird symbiotic relationship are astoundingly large, astoundingly orange, and textured like giant morels. We'll post the pictures Janet sent along with this Question of the Week so you can see why the words "Alien life form" often appear in emails about affected cedars.

Here's how it all happens. The spores of a virtually unpronounceable disease (Gymnosporangium) land on an Eastern red cedar (or, less commonly, another member of the Juniper family), creating small greenish brown swellings on the very tips of the evergreen's needles. That's it for the first year. The following season, the swellings…well…swell…into hard brown dimpled, gall-like structures. Then the galls develop those highly distinctive bright orange 'hanging lantern' alien thingees, especially in a warm, damp Spring.

Those big orange goobers then release spores into the air that cause small yellow spots to appear on the leaves and fruits of any nearby apple trees. Those spots then produce their own spores; sticky ones that attract insects ("and what about apple trees DOESN'T attract insects?" I hear all the fruit growers out there screaming at their radios?).

Those insects then spread the spores all over the tree, often ruining the crop for that season. The fungus then colonizes the undersides of the apple tree's leaves, forms a new kind of fruiting body down there, and those spores blow back onto the needles of nearby cedars, thus setting up the cycle for the following year. You got all that? I'm exhausted just thinking about it.

My old Rodale Press "Pest & Disease Problem Solver" says: "You can prevent the problem if cedars and apples are separated by at least four miles", adding that, "this is sometimes difficult to accomplish." Gee? You think? Another source says you only need 300 yards; which doesn't sound that far until you start thinking football fields.


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