Birches are popular landscape trees. Its bark texture and colour make them highly attractive landscape specimens. Two major insects affect this beautiful tree. One is the Birch Leaf Miner and the second is the Bronze Birch Borer.
In the urban environment, birch can be stressed and can become susceptible to a devastating insect, the bronze birch borer.
The Bronze Birch Borer adult is a slender, metallic-coppery beetle about 3/8 inch long and rarely seen. The larvae settle beneath the bark, and are white, segmented, legless grubs with an enlarged area behind the head. The larvae are about 1 inch long when mature. The larvae feed in the plumbing (phloem) of the birch, just below the bark. The feeding reduces the food sent to the roots. Decreased root growth and function lead to inadequate water, and the tree begins to die back, often starting with the upper crown.
Often, foliage on some branches in the upper crown begin to yellow in midsummer, progressing to dead brown leaves. This results in the death of smaller branches. Later, larger branches begin to die and the entire tree may eventually die. Ridges may be seen on the bark of the tree due to the larval tunnels beneath the bark. Adult beetles emerge mid to late June. Eggs are laid in cracks or crevices in the bark. The larvae emerge and enter the wood.
Borers seldom attack healthy, vigorous trees. The keys to keeping birches healthy:
- Select a location where the roots will be cool and moist, but where the leaves receive full sunshine.
- Sufficient watering is the most important factor in maintaining a healthy birch tree. During the growing season a, slow (2-3 hours), deep (8-18 inches) watering once per week is recommended.
- Mulching over the tree's root system will moderate soil temperatures and keep the soil moist. Ground covers will also keep the soils moist and cool
- Fertilizing is beneficial to ensure that nutrients are not lacking.
- Pruning should be avoided from May 1 to July 1. Female borers appear to be attracted to fresh pruning wounds.
Preventative treatments of insecticide on the bark can reduce the larval population if applied in late June and mid-July. Other methods may also be available - please contact us for details.
The larvae of this sawfly make the leaves of birch trees blotchy with dead tissue. The larvae feed between the top and bottom layers of the leaves. The damage causes the tree to look dead with wilted, brown leaves. The damage forces the tree to refoliate. This reduces its ability to produce food for growth. The damage may also make the tree more susceptible to borer attack.
Birch Leafminers are easily controlled with proper applications of systemic insecticides.
Acecaps is one way to treat birches for insect problems.
If you have a lawn/tree/shrub that needs some Tender Loving Care- get The KING OF GREEN: