Ash Whitefly is a native European and North African pest that has been harming ash, citrus, and other fruit trees throughout North America (in areas such as Southern California and Florida) since the late 1980s. Also known as the pomegranate, pear, or peach whitefly, it can produce multiple generations per year, thus creating issues throughout the growing season.
Ash Whitefly attacks a variety of ash, apricot, citrus, pear, pomegranate, and toyon trees.
Like other whiteflies, the ash whitefly attaches itself to the underside of plant leaves, feeding on plant sap. Infestation symptoms include: downward leaf curl, yellowing, premature leaf drop, and a sticky, residue called honeydew that promotes the growth of black, sooty mold fungi.
The Ash Whitefly has no natural enemies in California, but introductions of natural enemies from the pest’s native range are underway. Pesticide effects are limited because host trees have a semi-impenetrable, protective wax coating on their foliage. Insecticidal soaps can help, especially in washing off the sticky secretion that contributes to mold, but must be applied and re-applied often. Trimming affected trees so that foliage is clear of the ground, buildings and fences can help control secondary ant problems; however, the most effective treatment for ash whitefly is simply keeping trees as healthy as possible through pruning, fertilizing, and extra watering. Experimental yet promising treatments include importing natural predators (good bugs) from Europe and Africa to fight ash whitefly.