When a tree such as a weeping cutleaf birch has declined in health, the signs are often obvious. The tree’s drooping canopy will diminish and the birch may produce cankers, fungus or a lumpy texture from boring insects around its trunk. But a tree may already be unhealthy long before it shows blatant signs of declining vigor. Diagnosing a weeping cutleaf birch’s health is the first step in saving the tree from death.
Pick a leaf from the weeping cutleaf birch and look it over. One sign that a weeping cutleaf birch is in good health is that its leaves are properly shaped. Its leaves are ovate and deeply serrated. Each leaf point should extend approximately 1 inch from the mid rib. The leaves should emerge from the tree branches on alternating sides of each branch. They should be green in summer and yellow in fall.
Step away from the tree and look over the canopy. A tree infested with fungus or bronze birch borers will have a thinning crown. The leaves in the topmost part of the tree may be dead. A healthy tree will have a conical shape from which branches droop downward.
Examine the branches and bark closely. Healthy weeping cutleaf birch trees that are young will have white bark that peels from the tree easily. Older bark will be split in many places and will be colored black. Birches that have contracted a fungal infection may have had their bark peel away in locations to reveal the trunk beneath. These locations are known as cankers. The fungus infecting the tree may also produce fruiting bodies such as plate fungus. Cutleaf birch trees that are infected by bronze birch borer will contain ridges and bumps beneath the bark on the limbs and trunk. They may also have D-shaped holes or rusty brown stains where the insects chewed their way into the bark.
Peel the bark away from the trunk of the weeping cutleaf birch. A healthy tree will have a smooth, whitish green wood beneath the tree’s bark. Fungal infections will leave a spiderweb-like filament beneath the bark. Trees that are infected by bronze birch borer will have tiny, sawdust packed tunnels known as gallies where the insects chewed into the tree.
Push against the trunk of the weeping cutleaf birch at about head height. A healthy tree will be sturdy and will not easily push over.