Identity of pathogen that's infecting my Pacific wax myrtle #744469 - Ask Extension

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Identity of pathogen that's infecting my Pacific wax myrtle #744469

Asked April 15, 2021, 12:18 PM EDT

Hello, We purchased about 20 Pacific wax myrtle (native to the PNW) to use as a hedge and the ones that were planted in the fall became infected with some sort of disease. I think it might be the fungus-like organism Phytophthora taxon morella (https://pnwhandbooks.org/plantdisease/host-disease/california-wax-myrtle-morella-californica-leaf-blight) but I was hoping to get an expert opinion. We spent a ton of money on the plants and I want to prevent or at least inhibit future infections - for example, knowing whether fungicide is the best course of action. I attached several pictures. I also wanted an opinion as to whether the shrub will die if all of its leaves became infected, or if there's still a chance it will recover. Thanks! Brittany

Washington County Oregon

Expert Response

There was a similar situation in your area this spring with plants that had similar symptoms. Your plants, however, are showing more necrotic spotting. Unfortunately, even with images it is not enough to make a good diagnosis. Could be a foliar issue as you suggest but it is also consistent with a root issue as well. I have a few suggestions as to how to proceed.
First, contact the nursery where you purchased the plants and see if they have had similar reports from this same lot of plants. They may be able to contact the grower or have already been down this road.
Second, you could send leaves and even an whole plant into the OSU Plant Clinic to get a good diagnosis. Then you can really outline a good management plan.
https://bpp.oregonstate.edu/plant-clinic

You mention fungicides but anything that might be helpful will not be available in home garden packaging. You would have to hire a landscape company to help out with that. In fact, they might be able to help send a sample into the Plant Clinic. This might be your best option overall.
Jay Pscheidt Replied April 16, 2021, 9:18 AM EDT

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