My Riverbirch has been struggling for the past few years – treating it with water and fertilizer. This year, however, the whole top half is dead, no new growth. The bottom half has leaves, however, some are curled and brown. I’m not sure if this will survive or if there’s anything I can do such as trimming it back– would that help? Sadly, it may be on its last legs.
Thank you for contacting the Toronto Master Gardeners about your river birch (betula nigra).
I am sorry that your river birch is struggling. The river birch usually is a fairly easy tree to grow. As noted by the Missouri Botanical Garden website, the river birch requires the following growing conditions:
- Easily grown in average, medium to wet soils in full sun to part shade.
- River birch is perhaps the most culturally adaptable and heat tolerant of the birches. Prefers moist, acidic, fertile soils including semi-aquatic conditions, but also tolerates drier soils.
- Will tolerate poor drainage.
- Avoid pruning in spring when the sap is running.
While the river birch is one of the most – disease-free birches it may be weakened by hot summers and poor planting methods. If the tree is weakened, it will become vulnerable to the bronze birch borer, which typically infects and kills the birch. Although river birches have some susceptibility to aphids, leaf miner and iron chlorosis in high pH soils, these problems are somewhat minor in comparison to the birch borer.
Based on the description of the birch tree, it sounds like you may have bronze birch borer. Attached is the Toronto Master Gardeners Gardening Guide on the Bronze Birch Borer. All of our Gardening Guides are available on our website. For ease, the link is attached here. Please follow the instructions carefully. https://www.torontomastergardeners.ca/gardeningguides/bronze-birch-bororer-a-toronto-master-gardeners-guide/