Red leaf photinia is dropping leaves
For the past two summers, our red leaf photinias have been dropping their leaves and look like they are dying. In April and May they looked great. But now most of the leaves have dropped off except the top foot that still looks healthy. In the past, they have had black spot that caused the leaves to drop and we sprayed them with a little success. But, we haven't kept up the spraying. I have seen similar bushes near a freeway off ramp doing the same thing. Do you know what we ca do for this?
Washington County Oregon
Thank you for your question about your photinia. Without a photo of the leaves, it's difficult to diagnose the problem. However, the common denominator between last year and this is the presence of cool, wet springs--cooler and wetter than 'normal.' That is the perfect environment for a variety of fungi. Photinia are susceptible to one such specific fungus. If you don't notice the spots and don't treat the plant with fungicides when the fungus is still active, then the leaves turn black and fall off--one branch at a time.
There is nothing you can do this year, except rake up all leaves as they fall, and get rid of them (don't compose!) Here's a link to an OSU guide on the subject. Please note that two fungicides are available to home gardeners (Bonide Fung-onil and Bayer Advanced Disease Control), used per the labels and applied as the young shoots are developing, may stem the damage from the fungus. The attachment also shows what the leaves look like as the fungus takes hold. Please compare this photo with any not-yet-brown leaves.
Hope this is helpful. Good luck!