I am located at Oshawa, Zone 6. I planted a Prunus Accolade in my front yard 4 weeks back. The plant is around 3 feet tall and gets full sun. I recently started noticing holes in the leaves and the leaves eventually turn yellow and die out. I don’t see any aphids or beetles but notice ladybugs. Do I need to apply fungicide now or leave it as the plant is still young.
Thank you for contacting Toronto Master Gardeners
The Prunus ‘Accolade’ is a flowering cherry hybrid (P. sargentii x P. subhirtella) that requires full sun and well drained but moist soil. This species is native to Asia thriving in warm, humid conditions. They are also tolerant of cold weather and can survive in temperatures as low as -15 degrees Celsius. The Norwich Gardener website offers some caring tips for this tree.
We have been having cooler, less humid weather and the newly planted tree may be under stress. The website recommends regular watering for a newly planted tree, along with adding compost to the back fill when planting the tree. Ensure the planting hole has good drainage.
The prunus family is susceptible to powdery mildew and bark cankers which you do not mention. What you described is closer to Cherry shot-hole disease, commonly produced by two pathogens: a bacterial leaf spot caused by the bacterium Xanthomonas pruni and cherry leaf spot caused by the fungus Blumeriella jaapii, neither will kill your tree if the tree is otherwise healthy.
You need to pick up any dead leaves and dispose of them in the garbage. Keep the bottom of the tree clean of infected leaves to avoid reinfection. For your reference, the University of Maryland refers to this problem common to cherries.
Hope you found this information helpful.