Question: My photinia has died suddenly. It looked fine just a few weeks ago, and now there is nothing green. What hit it?

Answer: Probably cotton root rot, particularly if you live in an area with alkaline soils. You’ll have to replace it with a resistant plant such as the various large junipers or hollies. This is a soil-borne disease for which we have no reliable chemical control. If your photinia was part of a row, apply a sulfur soil-acidifier to the other plants, 4 to 8 ounces per square foot. That’s a heavy application of sulfur, but its function is to lower the soil pH, thereby lessening the probability of the disease’s spreading.