Birch tree dying - Ask Extension
I have 3 birch trees (Betula papyrifera) with large branches dying. The trees were planted in 2009 and thrived until the last couple of years. My loca...
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Birch tree dying #889477
Asked November 07, 2024, 11:24 AM EST
I have 3 birch trees (Betula papyrifera) with large branches dying. The trees were planted in 2009 and thrived until the last couple of years. My local landscape person thought it was a beetle and recommended cutting out the dead sections. We removed the dead portions but the dying branches are continuing to appear. Is there anything I can do to save these trees?
Washington County Oregon
Expert Response
Hi Ann and thanks for your question and picture of your birch trees. I'm afraid I have to agree with your landscape person as it sounds and looks like classic Bronze Birch Borer damage. I even see some woodpecker (sapsucker) holes which is a bird that goes after the beetle. I'll attach an article with more information but unless you are willing to do some pretty serious spraying, treatment is not recommended because the trees are already pretty much in decline.
The insect overwinters as a larva in the tree. As the weather warms in spring, the larvae resume feeding. They pupate in the tree. In late spring the adult insect chews a D-shaped hole in the bark to emerge. They lay their eggs in bark cracks or under bark flaps. The larvae hatch and bore immediately through the bark to feed on the vascular tissues. The life cycle takes one to two years to complete.
Your landscape person may be able to treat the trees with a systemic chemical (clothianidin or imidacloprid), but these will kill all the good insects that frequent the trees too. And the trees may be too infested for this control to work now. In the following article there are a few resistant birche varieties you could plant as replacements at the end of the "cultural control" section. You will also read that trees stressed by heat, lack of water or other insect attacks are less able to resist the borer. With our crazy hot summers lately, all trees need additional watering.
https://pnwhandbooks.org/insect/hort/landscape/hosts-pests-landscape-plants/birch-betula-bronze-birch-borer
Sorry it's not better news,
The insect overwinters as a larva in the tree. As the weather warms in spring, the larvae resume feeding. They pupate in the tree. In late spring the adult insect chews a D-shaped hole in the bark to emerge. They lay their eggs in bark cracks or under bark flaps. The larvae hatch and bore immediately through the bark to feed on the vascular tissues. The life cycle takes one to two years to complete.
Your landscape person may be able to treat the trees with a systemic chemical (clothianidin or imidacloprid), but these will kill all the good insects that frequent the trees too. And the trees may be too infested for this control to work now. In the following article there are a few resistant birche varieties you could plant as replacements at the end of the "cultural control" section. You will also read that trees stressed by heat, lack of water or other insect attacks are less able to resist the borer. With our crazy hot summers lately, all trees need additional watering.
https://pnwhandbooks.org/insect/hort/landscape/hosts-pests-landscape-plants/birch-betula-bronze-birch-borer
Sorry it's not better news,
