Newspaper article The Topeka Capital-Journal

At Home: Cedar-Apple Rust Can Reduce Fruit Tree Yield

Newspaper article The Topeka Capital-Journal

At Home: Cedar-Apple Rust Can Reduce Fruit Tree Yield

Article excerpt

Are your cedar trees and junipers looking like they have been decorated for Christmas -- except the colors are all wrong? Bright orange "balls" are showing up all over the place. What is the deal?

Relax. It is called cedar-apple rust, and it rarely harms evergreens.

Cedar-apple rust is a fungus that looks peculiar, almost like exotic flowers. It has a very interesting, almost cosmic, life cycle.

Let's do a flashback, like they do on television: Two years ago, in a galaxy far, far away, (OK, closer to 2 miles or less), dusty- orange spores developed on the underside of leaves from apple and/ or hawthorn trees. July and August winds shuttled the spores to junipers and cedars, where galls developed very slowly. At first, they looked like reddish-brown bumps. In spring, they appeared as small twig swellings. They spent the summer basking in the sun and enlarging. By the following spring, they had grown to a width of a half-inch to 2 inches.

"Grown-up" galls look a bit like wrinkled brown balls until they swell in spring and produce multiple gelatin-like tendrils, which are a particularly bright orange during rainy weather. This is the "exotic flower" you are seeing. The cedar-apple rust galls will dry up and fall off this summer. The cedar-hawthorn rust galls may last for several years.

This same bright orange fungus (exotic flower) returns the favor and sends millions of spores back to the apple and hawthorn trees. In late spring or early summer, bright yellow-orange spots, about one-eighth inch to one-quarter inch in diameter, form on the upper surface of the apple and hawthorn leaves. Small black fruiting structures form in the center of the lesion and may ooze orange "gelatin" during wet weather.

Eventually, an orange, cup-like fungal structure forms on the bottom surface of the leaf directly beneath the lesion. This produces the new dusty-orange spores that sail back to the cedar and juniper trees in July and August, completing the two-year life cycle.

Now comes the dreadful part. While the evergreens remain virtually unscathed, the rust fungi can result in considerable damage to their deciduous hosts. …

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