Jeremy, a faithful reader from Nashville, writes, "When we moved into our house two years ago, our driveway was lined with 6 enormous red-tip photinias. Since they were taking up driveway space, we had them pruned in the early spring of 2015. That summer they were covered by their signature red leaves and looked healthy. However, this summer has been a different story. They trees look diseased with very few healthy leaves and the rest are covered with spots and holes. They look so bad that we think they are about to croak. Can they be saved with a fungicide or fertilizer? Or should we plan for replacements?
Grumpy's 412% Guaranteed Correct Answer: Red-tip photinias (Photinia x fraseri) planted in the rainy, humid climate of the Southeast are subject to a virulent disease called Entomosporium leaf spot. The leaf spot attacks only new, bright red leaves and spreads from leaf to leaf by splashing water. Small red spots appear that grow larger and coalesce. They develop silvery or tan centers with dark purple borders. Take a look.
The more you trim these shrubs, the more red leaves you get, and the more disease too. Eventually, diseased leaves drop, branches die back, and the whole shrub dies. You can control leaf spot by spraying the new foliage according to label directions with Immunox or Daconil, but I'd replace them with something better, such as holly, sasanqua camellia, holly osmanthus, or Japanese cleyera. FYI -- this leaf spot tears up Indian hawthorn too.
Readers in southern California, west Texas, and places with similar arid climates will undoubtedly be happy to know that this disease is a not a big problem there. But if you live anywhere that receives more than 35 inches of rain a year, don't plant red-tips.