Answer: What you describe sounds like photinia leaf spot, a fungal disease. 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. Since your plants have already leafed out, it's too late for sprays. But, you can prune your plants back to encourage healthy new growth. The newer leaves can then be protected as they begin to emerge (as explained above). Best wishes with your shrubs!
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