Published: May 09, 2008 01:15 pm            

What’s that on my cedar tree?

EDMOND — If only I had a nickel for every time I’ve heard that question this week. The orange-gelatinous masses that local residents are spotting in their cedar trees has been described many ways; ranging from a jellyfish, to Christmas ornaments, to a hazardous material. Don’t be alarmed. We do not have jellyfish, and we certainly don’t need to call in a Haz-Mat team. The formations being seen in the cedar trees are Cedar-Apple Rust, which is brought on by a fungus.

This rust is unique in the fact that it only can persist when both cedar and apple hosts are present. On the native red cedar and ornamental cedar trees, Juniperus spp., cedar-apple rust is not known to be extremely damaging; however, some ornamental cedar can become so covered with galls that they become unsightly in the landscape. When the rust becomes apparent on an apple tree the chief cause of damage is premature defoliation (leaf drop). Affected fruit are smaller, deformed and undesirable for marketing.

Under some backyard conditions where both hosts (cedar and apple) are located close together, both trees have been killed by this disease.

If you have not seen these yet, I would suggest taking a walk with the children and look for them. The gel-like material has mostly dried up by now, but the ball shaped galls still are present on the tree. If you have an apple tree on your property a spray schedule should be started now to prevent failure of the apple crop. Call the Extension Office at 713-1125 for information on recommended fungicides.

The best way to prevent this problem is to plant apple trees in a spot that is separated from, or upwind from a cedar tree. Also remember to mark your gardening calendar to remove the galls in January before they have the chance to reach the gel-stage.

An easy way to remember this is when you’re taking down your Christmas decorations inside; remember to take the decorations off your cedar trees outside.



SAMANTHA SNYDER is a horticulture educator for the Oklahoma County OSU Extension Service.

        

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