Question
Holly leaf black powde
I have two holly bushes with black powder on the leaves and stems and coating the gravel underneath. The underside of the leaves have white, scaly spots, and some tan-colored spots that look like they may be small, round insects. If I squish the tan-colored spots, they spurt out a little bit of clear, sticky substance. The tan-colored objects also come off the leaves rather easily. A picture is attached.
AnswerDear Mike, You have a fantastic classic picture of scale on your holly. Scale is an unmoving insect that affects many plants, but they are very fond of holly. They also produce the black soot that is covering the leaves. You may also have some mealybugs in there; they are white and fuzzy and move very slowly and are a slow moving type of scale. Your question is actually the second one on scale I have had today, as they are very common in summer. The cure for them is very simple, just somewhat tedious. Spray the entire plants with horticultural oil (my favorite is SunSpray), top and bottom (especially bottom!) of leaves. The oil smothers the scale and it will eventually drop off. It will also flake the black soot off the leaves. The soot will come off fairly quickly, but you will need to spray the scale every week for several weeks to get most of it off. It is well worth the doing, because as soon as the scale is gone, the hollies will really look great and start growing faster. Please write back if you need further assistance. Good luck, Melissa
