Trees Looking Unhealthy – Serviceberry, Laburnum

(Question)

I live in Toronto. At the back of my townhouse garden (facing south), I have a serviceberry tree one of several planted 17 years ago. Mine is now looking unhealthy – leaves curling up. It can’t be lack of water this year. What do you suggest? Should I fertilize it & if so, which fertilizer?
In my front garden (facing north), I have a Golden Tail Laburnum, on which the leaves are turning brown & the leaf coverage seems very sparse. It did bloom well this spring. Same question – what to do? Thanks for your advice on this.

(Answer)

The serviceberry likes to be in an area with lots of sun and well-drained soil. It sounds like your tree gets enough sun. However, it is possible that this summer has been excessively wet for the soil, such that the plant is unhappy.  Do the other serviceberry trees in your garden area look healthy, is it just this one that has the problem?

It is possible that your serviceberry has been attacked by diseases or insects, but if curling leaves are the only symptom, this is not likely.

Check out a couple of earlier postings on the Ask a Master Gardener website:

  • Serviceberry Help – This discusses ideal conditions for serviceberries, as well as some diseases/insects that can afflict the trees. For example, Entomosporium leaf spot causes spotting and partial defoliation, in particular if there has been lots of rain. However, you don’t mention any spots on the leaves – which would be a sign of this infection.
  • Something on my serviceberry leaf  – This posting addresses curled leaves from insect infestation – these leaves would likely have a sticky honeydew on the undersides – something you don’t mention.

As for your laburnum, there are a few reasons leaves can turn brown – including pests, diseases and environmental factors.  As you don’t mention any other problems with the tree (e.g., spots, evidence of insects, etc), I suggest that the culprit is our excessively wet summer.  Laburnum trees need well-draining soil and don’t like soggy ground – this may be contributing to the sparseness and discolouration of the leaves.

See the Royal Horticultural Society’s Waterlogging and flooding.

As too much rain can wash nutrients out of soil,  fertilizing the trees is a good idea.

I suggest that you examine the trees closely to see if there are other signs of pests or disease – if so, write us again, and if possible, send a photo.

Here’s hoping next summer is a little drier!