The birch tree is a deciduous tree with many different species. The birch tree is well liked for its exceptional bark characteristics and lovely delicate foliage. Many of the species may be used in landscapes. The birch tree is a favorite ornamental tree but difficult to keep healthy for a long life. Typically birch trees begin to decline within a few years, and many die well before reaching maturity. A healthy birch tree should live 40 to 50 years. Birch trees can be bothered by many diseases and pests.
Types of Birch
The two more common types of birch trees are the yellow birch, Betula alleghaniensis (lenta), and the European white birch, Betula pendula (verrucosa, alba). The yellow birch is hardy in USDA zones 4 to 6. It prefers cool, moist soil on north-side slopes. The dark green leaves are oval and 3 to 5 inches long. In the fall they turn a pretty yellow color.
European white birch can reach 40 to 60 feet tall. It is hardy in USDA zone 2. In the summer, its green leaves are 1 to 3 inches long. In fall they turn yellow but do not drop until later in the season. The trees prefer cooler temperatures and moist soil and are attractive landscaping trees.
Birch Lace Bug
The birch lace bug, Heteroptera: Tongidae, includes approximately 17 species of bugs that prefer certain hosts. The yellow and white birch are two of the favorite hosts. The lace bugs are very small, only about 1/4 to 1/8 inch long. The body is brown to black, and its wings are somewhat transparent.
The adults survive the winter, and in the spring the females lay their eggs on the lower leaves of the tree and cover them with a brown substance. These spots are very noticeable when infestation is heavy. The eggs spend 30 to 45 days in the nymph stage before becoming adult. There can be three to five generations of lace bugs per year.
Adult lace bugs as well as nymphs can damage a birch tree. Lace bugs have piercing-sucking mouth parts that remove the fluid from the tree leaves. This can cause the leaves to turn color, reduce the tree's heartiness and cause the leaves to fall off early. Another symptom is similar to chlorosis, or the lack of chlorophyll, in the upper leaves. The leaves develop flecks that are yellow or white and larger than those caused from other insects. In serious infestations, whole patches of a leaf can turn brown.
To prevent lace bug infestation, properly care for the birch tree so that the tree is healthy. The trees should be watched closely for signs of the lace bug. Occasionally, treatment on deciduous trees is not required because the chlorosis effect cannot be reversed. Trees that are attacked heavily do not usually have heavy infestation again the next year. If deemed necessary, insecticides can be applied from late May to early June when the nymphs are young. The insecticide should be directed at the underside of the leaf so that it is thoroughly covered. The application can be repeated in 10 to 14 days if necessary.