Bozeman Residents Find Alien-like Growths on Trees

Bozeman residents are seeing a strange, gelatinous growth on junipers and other trees around hiking trails and yards throughout town.

Though some may be concerned about the potentially harmful growths, it seems that the ominous-looking masses are more bark than bite.

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Known as cedar apple rust, these growths are a fungus commonly found, as the name implies, on apple trees and other Rosaceae crops (in the rose family). According to the United States Department of Agriculture, the fungus requires two hosts throughout its lifespan. These hosts are juniper and Rosaceae crops, and most of the time, in order to be successful hosts to cedar apple rust, they have to be within roughly a mile of each other.

The fungus spends different periods of its life cycle on different hosts. On certain Rosaceae crops, like apple, crabapple, and hawthorn, the fungus causes orange lesions on leaves that resemble rust.

On junipers, it manifests as teliohorns, the gelatinous spikes seen throughout Bozeman.

Cedar apple rust can also decrease apple crop yield and create blemishes on the fruit, potentially lowering the value of apple crops.

It's usually found in open areas, so keep an eye out for it along dirt roads, trail heads, pastures, and orchards. It's also more common with frequent rains and higher humidity.

While the fungus isn't good news for apple trees, it doesn't harm junipers, aside from being unsightly. It's easily treated with a labeled fungicide, but unless you have apples nearby, it likely isn't worth the effort to remove.

If you do decide to remove it, make sure you're reading your fungicide labels! Fungicides are species-specific, so what's labeled for junipers may not be viable for use on apples—especially if you're eating the apples.

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