You may have noticed many Birch trees around town in yards and parks with brown leaves over the past few weeks. There has been an outbreak of Birch Leaf Miner this year which seems to have affected the majority of Birch trees in and around Chestermere.
The Birch Leaf Miner is a sawfly which lays its eggs in the leaves of the Birch tree. The larvae then develop inside the leaf membranes and feed on the inner green tissue of the leaf causing a discolored spot. Feeding over several weeks causes the blemish to turn brown, papery and can destroy much of the leaf.
Most infestations will not cause any long lasting damage to the tree but heavy attacks over a period of years causes stress, making the tree more susceptible to other problems. Most varieties of Birch are susceptible including Cutleaf Weeping, Paper and Pinnacle. Keeping your trees healthy is the best way to prevent severe outbreaks of Birch Leaf Miner as they will attack stressed trees.
Some tips to help keep your trees healthy and ward off Birch Leaf Miner attacks:
- Proper Site Selection – Roots of Birch need a cool, moist area. Mulching around the root zone is an excellent way to keep the roots cool and will help hold moisture in.
- Fertilizing – Best done in early spring as the tree is starting to leaf out and grow.
- Pruning – Best done during June and July, prune out any dead wood and remove any branches that are rubbing, broken or diseased.
- Watering – Birch like water, make sure to water the area under and around the root zone thoroughly at least once per week in periods of little rain. More if it is a new un-established tree.
- Avoid damage by lawn mowers and weed whippers, remove sod around base of tree and replace with mulch or groundcovers.
You can also contact your local Garden Center about control methods for Birch Leaf Miner.
