Archived Story

Reasons for white, red oak decline different

Published 9:47am Monday, December 10, 2012 Updated 11:48am Monday, December 10, 2012

The U.S. Forest Service is predicting that our oaks will be dying faster over the next 15 years. Linda Haugen and Glenn Rosenholm of the service are bearers of the bad news.

There are several factors including species, site condition, tree age and stress. In Missouri, Iowa and Indiana white oaks are affected. It’s the red oaks in Michigan. The most vulnerable trees are the very young and the very old. The factors causing white oak decline seem to be different from those causing the loss of red oaks, according to Missouri Dept. of Conservation Forest Entomologist Rob Lawrence (he’s a bug specialist).

Different factors can contribute to the same end result. For example, drought or gypsy moth defoliation can start the decline.

These already stressed trees are more readily killed by two-lined chestnut borers, Armilliaria root disease or the red oak borer. Droughts for an extended period, as we have had, will contribute to the problem with both red and white oaks.

Rob Lawrence thinks this will cause a decline in tree health in general. Wood boring insects, such as the red oak borer in the natural landscape and the flat headed apple tree borer in city landscapes will also be a problem he predicts.

In Michigan the most oak deaths are in pin oaks on poor soil. Since many species of oaks will grow in sandy soil, drought will really hit them hard. Many of our oaks are burr oaks and they too have a problem — bur oak blight.

Even though all this information is related to other states don’t get too cocky. Our drought is not to be sneezed at either. We have the two-lined chestnut borer in Otter Tail County already.

The only thing you can do to protect your oak trees is to water them religiously. Don’t just wave the hose at them either. Soak the soil until it squishes when you walk on it.

Water at least one-third wider than the drip line as the tree has roots that far out from the trunk. Mulching will help too. Since not much grass will grow under an oak anyhow, you can just as well cover the area with leaves or bark mulch.

Enough bad news. The good news is that the seed catalogs are appearing in our mail boxes. Gardeners are like kids in a candy store, drooling over the pictures in those books.

Order seeds from them, but not plants or trees unless you absolutely can’t find them locally. There may be a good reason why they are not available here, our weather.

A tree that must be shipped to you is going to be bare root, much smaller than a potted one and already stressed by the time spent in transit. The same applies to plants.

We have nurseries in every direction and they all have perennials and trees just for our extreme climate. Buying locally also keeps the money here — not in Kansas, Dorothy.

So, wipe the drool off your chin and start planning next summer’s gardens.


Bev Johnson is a master gardener for Otter Tail County.

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