Serviceberries losing leaves too early.
We have 4 serviceberries in our yard, planted about 15-20 years ago. For the past 3 years or so they have had beautiful flowers, lots of berries, but as soon as the berries have ripened the leaves start to turn orange and fall. This year, the leaves were all but gone by mid September, just a few left at the tops of the branches. We are in Van Buren County and have quite sandy soil. We water during dry spells. The trees get partial sun. There is a large oak tree in the middle of the lawn with the serviceberries planted around the edges of the lawn - past the branches of the oak. The trees are underplanted with hosta. We have not noticed any bugs or spots or mildew. The only other things that might be worth noting are that we have a problem with ground squirrels and we are not very good about fertilizing. Any recommendations would be appreciated. Thank you.
Van Buren County Michigan
I just happen to have an older serviceberry with the very same issue. The tree is approximately 30 years old and is bare by the end of September every year, and has happened for years. The tree exhibits no fungal or pest issues and leafs out robustly and flowers beautifully each year. Mine too is underplanted considerably, with hostas, lily of the valley, and others. This is no doubt a factor because of competition for water and nutrients. Your oak tree roots may be a challenge in this competitive way as well. And if your soil is sandy it means that water is not held for long. You may be watering but how much of it is actually getting to the tree because of the aforementioned competition? Then there is usually a dry period in the heat of summer, even in wetter years such as this year was. Watering long and deeply at this time would certainly be helpful.
Serviceberries are tough trees, hardy natives to our region, a zone 3 plant. With no fungal or pest issues, the problem just about has to be in the soil. It is also possible it is a characteristic of older serviceberries, because I have heard of others losing leaves the same way, though I can't find any professional research documenting same. My guess is that your's will pop out come spring like nothing ever happened. At least that is what mine does. Look at the buds on the branch tips and I suspect you will find healthy reddish looking buds. Fertilizing in spring would certainly help. Best way to do that is to deep fertilize with a Ross Root Feeder. Best time to do that is after flowering, replacing some of the large amounts of energy consumed in flowering. I have not done so but will come spring now that you have me thinking about it.
If you wish to pursue it further you could submit a soil sample for a soil test, which would reveal any irregularities. https://homesoiltest.msu.edu/ Tell them what is happening and after culturing out the soil they will advise to exactly what amendments may be needed for optimum growth. I have not done this as yet because my tree is otherwise healthy.
Finally, if you think your trees do not look healthy, contact a Certified Arborist, one who specializes in everything woody. You can find one or more Certified Arborists in your zip code at www.treesaregood.com Click on the Find an Arborist tab. He/she will utilize all factors such as how it is growing, where it is growing, what's growing around it, etc. On site arborist evaluations are not expensive and are the best way to get to a positive diagnosis.