Plant Pathology Infobytes

March 24, 1998
Keeping Photinia Leaf Spot Under Control

Keep your photinias from "blighting-out" by continuing a spring fungicide application program for Entomosporium leaf spot. This disease, also referred to as photinia leaf spot, is the number one problem for an otherwise great landscape plant.

Photinia leaf spot is caused by a fungus which starts its disease cycle early in the year. So practicing preventive medicine before new growth becomes infected is the way to handle this problem. Don't wait until next June after photinias have become heavily blighted before beginning a control program!

Did you have a photinia leaf spot problem last year? Let's review some of the symptoms of this disease to help you make a decision about whether this disease has caused problems in your landscape.

Photinia leaf spot shows up as small, circular, bright red spots on upper and lower surfaces of young expanding leaves. These are the first symptoms of the disease. As the disease progresses, the spots merge and blighted leaves often fall from plants. Badly infected photinias usually suffer extensive defoliation and, as a result, don't grow very well. Plus the disease detracts from the appearance of plants.

How do you go about controlling photinia leaf spot? A good way to start, if you haven't already done so, is to rake and destroy diseased foliage from last season. This practice is an essential part of the control program since it removes one of the main sources of fungus inoculum.

Fungicide sprays are also generally necessary in a control program for this disease. Best control of photinia leaf spot is obtained with preventive sprays timed from bud break and applied every ten to fourteen days until all foliage has matured. Mature foliage is no longer susceptible to infection. Provided applications are made on schedule, plants should not be affected by leaf spot.

Fungicides that will do a good job of handling photinia leaf spot include formulations of chlorothalonil such as Spectracide Immunex Multi-Purpose Fungicide, formulations of chlorothalonil such as Dragon Daconil 2787, Ortho Multi-Purpose Fungicide Daconil 2787, Security Fungi-Gard, Black Leaf Lawn and Garden Fungicide, Pennington's Pride Multi-Purpose Fungicide, as well as formulations of mancozeb. A commonly available brand of this latter fungicide is Dragon Lawn and Vegetable Disease Control.

Other trade name chlorothalonil and mancozeb are generally available at garden supply stores, so check with your dealer for product availability. Refer to product labels for dilution rates and other information regarding application.

For additional information, please feel free to check with us at the County Extension Office.


Written by the late Dr. Frank Killebrew

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