Answer: 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!
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.
A good way to start controlling the disease, 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.
Pesticides labeled for Entomosporium Leaf Spot contain the active ingredients chlorothalonil (Ferti-Lome Liquid Fungicide; Bondie Fung-Onil Multipurpose Fungicide; Hi-Yield Vegetable, Flower, Fruit, & Ornamental Fungicide; Ortho Garden Disease Control), propiconazole (Banner Maxx, Bonide Infuse Fungicide, Ferti-Lome Liquid Systemic Fungicide), or myclobutanil (Spectracide Immunox).
Be sure to follow label directions.
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