Birches are deciduous trees that like cool, moist sites similar to the mild climates of their native habitats in Europe and Asia. If they are not planted in a cool position, they can suffer from stress and become unhealthy. When birch trees get weak they can suffer from infestation from pests called bronze birch borers. These can kill trees within a few years of planting. Paper birch and river birch are the most popular varieties of birch for planting in gardens due to their attractive bark and catkins in early summer.
The botanical name for paper birch is Betula papyrifera but it's also called white birch, canoe birch or silver birch. Distinctive white papery bark provides seasonal interest throughout the year and this makes it a popular tree for landscaping. It can reach 30 to 40 feet high and can live 140 years. Paper birch is particularly susceptible to bronze birch borers if it is planted in hot dry sites. For this reason, it is more commonly planted in Northern America and Canada rather than regions with warm temperatures.
Loose, papery bark that is two-tone red and brown is the distinguishing feature of the river birch. Also known by its botanical name Betula nigra, this tree is resistant to the bronze birch borer and will tolerate a wide range of soil conditions. It can reach 40 feet high and has a lifespan of 50 years.
Bronze Birch Borer
The bronze birch borer is a bronze coloured beetle, 2 inches long, that lays its eggs underneath the bark of birch trees. Larvae eat their way through inner bark and the tree's cambium layers after emerging from eggs. The tunnelling weakens the tree and birches affected by the beetle can die.
Plant birch trees in a cool north-facing direction or where the root zone is shaded. During heat waves or drought, remove turf grass with a spade and spread a 2-inch layer of mulch beneath the branches, such as wood or bark chips, to keep the soil cool.
Birch Leaf Miner
Birch leaf miner is the larva of a small sawfly that lays its eggs on new leaves in May. Hatched larvae feed on leaves, and although not serious in the early stages, long-term infestation over several years can cause decline in growth. Use a systemic tree insect killer according to manufacturer's instructions to eradicate the pest.