White Birch

WHITE BIRCH.

The Reason Why These Trees Have Been Dying.

Ann Arbor, April 5, 1899.

Editor of the Argus:--It may not be out of place at this time to give a word of warning as to the disease of the white birch. Our citizens generally, have probably noticed that the white birches, especially the cut-leaf, weeping variety, have been dying in this vicinity for two years. an examination of scores of trees in the is city shows that all diseased trees are infested by an insect borer, and that all healthy trees contain no borers. It is  therefore safe to say that this borer is the cause of the disease. The tree when affected begins to die at the top, the withering of leaves and drying out of branches progressing downward.

The presence of the borer may be readily discovered by the ridges appearing externally in the bark. The insect works mostly in the inner layer of the bark or in the young wood. Wherever it bores, the tree immediately begins the formation of a healing tissue, and this excessive tissue formation raises the bark in ridges or welts. The disease does not seem to be a new one, but becomes striking at this time because the insects are excessively numerous.

There is no remedy against this pest except the birds and the burning of the trees. The cold winter has not killed the larvae. The mature beetle comes out of the trees in June, and soon after lays its eggs in the bark. The eggs hatch and the young larvae bore into the tree the same summer. Obviously if the insects are to be destroyed, they must be taken while in the wood before they come out to lay their eggs. in May therefore every birch tree should be examined for the welts on the bark, and all showing these welts should be cut out and burned. It is often found that the trunk of the tree near the ground shows the presence of the borers; in such a case the whole tree should be destroyed.

F.C. NEWCOMBE.