Question: My camellias are covered with an ashen-looking material. What is it, and how do I control it?
Answer: That’s tea scale, and it’s a scourge where camellias are common. You’ll need to spray the plants with a horticultural oil spray during the late winter, just after they finish blooming and before they start growing. You can also use a systemic insecticide spray or a summer-weight oil if you find the scale insects during the growing season, but read and follow label directions carefully to avoid damage to the plants.