Hello, I planted a large (7 gallon) multi-stemmed serviceberry (amelanchier gran Autumn Brilliance) in June of last year to keep my birds happy! Unfortunately, my serviceberry has not produced any berries and has been hit by both leafminers and mildew (and maybe rust?). I have been picking off the leafminers to kill them. I read that neem oil can be a good product to use for both powdery mildew and leafminer control. I’ve underplanted and nearby planted with other native plants including St John’s wort, butterfly milkweed, and cardinal flower. These are all alive with bees and other pollinators. I read that neem oil does not affect beneficials, but want to double check with you! (http://npic.orst.edu/factsheets/neemgen.html#:~:text=Neem%20oil%20is%20practically%20non,fish%20and%20other%20aquatic%20organisms.) So: 1. Would you recommend neem oil for this issue? 2. If not, what would you recommend? 3. Will beneficials be safe? (I would not be spraying the other plants of course, but there is bound to be some overspray.)
Thank you so much for your assistance. Trying to do things the least invasive way possible, but my serviceberry looks absolutely dismal (amid a garden of colour!).
Firstly, neem oil is not registered in Ontario for use as a pesticide.
Looking at the back of the leaves will help you to determine just which disease your serviceberry has. It is certainly the case that they are very subject to fungal infections, specifically cedar-apple rust and hawthorn rust. Here is a good guide to both from the University of Minnesota Extension Department.
Try to keep leaves as dry as possible by using soaker hoses or hand watering the soil rather than the plants. Improve air circulation as much as possible, thinning out the shrub as necessary.
Generally, the frequent application of fungicides is not recommended or warranted. The shrub/tree will not die from this infection but, unfortunately, it is slightly unsightly. Good hygiene practices when pruning and careful removal of any dropped leaves & debris is critical now and into the fall (do not home compost any of this material).
Note: the one described in the Minnesota document is NOT permitted for use by home owners in Canada.
Consulting an arborist or tree care specialist is another option if you are really concerned about this tree.
Hope you find this helpful.