pyracantha bush has grayish-black hive-looking lumps
My pyracantha bush has grayish-black hive-looking lumps on many branches. Shrub looks healthy but has been leaning forward and some branches weak. Could this be black knot disease? They are comprised of small round lumps all clustered together and are very hard. The bush is very old and over six ft tall. Thank you!
Certified GKH Gardening Expert
Black knot does not generally affect these shrubs, though it's not improbable. It may likely be brown scale insects, which can form clumps on branches. These can be treated with neem oil. Here is more information: https://www.gardeningknowhow.com/plant-problems/pests/scale-bug-how-to-control-plant-scale.htm