Strange growth on juniper bonsai

Discussion in 'Garden Pest Management and Identification' started by Lynnedq, May 12, 2008.

  1. Lynnedq

    Lynnedq Member

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    Vancouver, BC, Canada
    My bonsai, a Chinese Juniper which I leave in an unheated garage all
    winter, recently developed a strange growth after being brought outside: about 2 dozen fingernail sized, gelatinous, odorless, orangey-brown blobs were stuck to the branches. A few days later, when the weather was drier, the blobs had shriveled and were almost invisible. After a few more wet days, they returned but only partially. Now there's just a tiny bit of brownish sticky residue where they were.

    Coincidentally, I've recently seen a similarly-colored sticky substance (not sap)
    on the branches of a large coniferous shrub (possible another type of
    juniper) in my neighborhood. Do you have any idea what this stuff is, and if
    it's harmful , how should I treat it?
     

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  2. Michael F

    Michael F Paragon of Plants Forums Moderator 10 Years

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    One of the Gymnosporangium juniper rust diseases. Not sure if it is treatable.
     
  3. Lynnedq

    Lynnedq Member

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    Thanks very much for identifying the problem. After further research into gymnosporangium I've learned that this ugly fungus is common in junipers, particularly bonsai, and to survive it requires apple trees in the vicinity (it's also known as cedar-apple disease). The only treatment recommended is to spray with a fungicide in mid to late summer, when the spores that have spread from the juniper to broadleaf trees tend to drift back on to the juniper. Here's hoping it works!
     

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