Monday, May 11, 2009

A fungus among us

Cedar apple rust is is full bloom. OK not bloom; it is shedding spores from its "telial horns" if you want to get technical about it. Folks brought lots of samples into the Extension office last week.

If you look at our native Eastern Red Cedar, (which is actually a juniper, Juniperus virginiana)you'll see these nifty orange, gelatinous masses of fungal tissue. The warm, wet weather we had recently was ideal for them to burst into maturity. The spores that are released from these slimy galls are carried in the air to the alternate host for the disease... apple. In fact there are several related rusts which affect hawthorn and quince as well. The deciduous, alternate host (apple, etc) will develop bright orange spots on leaves later this spring and fruit on these plants may become rusty, russeted and malformed.

So, cedar-apple rust and it's relatives are very interesting plant diseases. Two unrelated plants sharing a disease. And for most of us, that's all there is to it.. an interesting disease. It sometimes causes damage to Junipers in landscape settings; unless you are growing apples to eat, the leaf spots it causes are not a big deal. Backyard fruit producers have a couple of options. Spray fungicides (last week would have been perfect) or grow apple varieties that are resistant to this disease. There are crabapple varieties that are resistant, too.

No, there are worse fungi among I. Apple scab, anthracnose, powdery mildew.... spores of all of these diseases are thicker than pollen in our current atmosphere. Their signs of infection will be showing up soon. Stay tuned for pictures and horror stories from the world of plant disease.

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