Photinia - Ask Extension
Is this photinia healthy? The condition of the bark makes me wonder. Typically, the leaves become diseased and fall off. However, many leaves still su...
Knowledgebase
Photinia #885690
Asked September 18, 2024, 11:14 AM EDT
Is this photinia healthy? The condition of the bark makes me wonder. Typically, the leaves become diseased and fall off. However, many leaves still survive. Thank you for your response.
Montgomery County Maryland
Expert Response
We don't see any concerning symptoms on the bark, though we don't often see Photinia bark this distinctly since many gardeners prune their plants to much more compact sizes, where the dense foliage hides the bark. (There is nothing wrong with your allowing the plant to mature into its full, small-tree size. In fact, it's probably healthier overall for it, even though it still gets some leaf infection.) The leaf disease you mention is likely Entomosporium Leaf Spot, a very common infection that Photinia is vulnerable to.
Although using a copper-based fungicide spray on the foliage might suppress new infection on healthy leaves, it cannot cure existing infection, and is not generally practical to try. This is in part because every spring (and probably several times thereafter into the summer), the entire canopy of the plant would need to be coated in fungicide spray, and this repeated every year in order to keep the infection at a minimum. Since fungicide use might risk harm to pollinators and other organisms, and because they don't always work completely (if it rains when a follow-up treatment is due, for example, the break in the spray cycle can allow infection to take place), we don't usually recommend their use.
You can rake-up fallen leaves each season, though, that were shed due to disease or normal leaf drop (since even healthy evergreens do still drop a few of their oldest leaves each year). This will remove some infectious spores so they don't overwinter under the plant, able to start new infections next year. While spores might still blow into the area on the wind in a future year, at least removing infected leaves on the ground will help reduce the risk of severe infection. In years with wet weather, infection might be more rampant, since leaf surfaces that stay wet for long periods tend to be easier for pathogen spores to infect.
If this particular leaf spot infection is too tedious to deal with or creates too much of an eyesore, and if you're not keen on keeping the plant, then replacing it with another species might be the more practical long-term solution.
Miri
Although using a copper-based fungicide spray on the foliage might suppress new infection on healthy leaves, it cannot cure existing infection, and is not generally practical to try. This is in part because every spring (and probably several times thereafter into the summer), the entire canopy of the plant would need to be coated in fungicide spray, and this repeated every year in order to keep the infection at a minimum. Since fungicide use might risk harm to pollinators and other organisms, and because they don't always work completely (if it rains when a follow-up treatment is due, for example, the break in the spray cycle can allow infection to take place), we don't usually recommend their use.
You can rake-up fallen leaves each season, though, that were shed due to disease or normal leaf drop (since even healthy evergreens do still drop a few of their oldest leaves each year). This will remove some infectious spores so they don't overwinter under the plant, able to start new infections next year. While spores might still blow into the area on the wind in a future year, at least removing infected leaves on the ground will help reduce the risk of severe infection. In years with wet weather, infection might be more rampant, since leaf surfaces that stay wet for long periods tend to be easier for pathogen spores to infect.
If this particular leaf spot infection is too tedious to deal with or creates too much of an eyesore, and if you're not keen on keeping the plant, then replacing it with another species might be the more practical long-term solution.
Miri
With many thanks for your help.
You're welcome!
