Key Features
- Stunted growth
- Sticky, curled leaves with white wax
- Black sooty mold
Symptoms
Individuals feed on roots, stems, and fruits. Feeding results in large amounts of honeydew which promotes the growth of sooty mold. Stem feeding will cause formation of galls. Leaves can become curled. Extensive damage can occur when individuals crawl down to roots and cause galls. Heavy root infestations will result in yellowing of leaves. Underground root infestations are of more concern than above ground infestations.
Biology
Woolly aphids usually overwinter underground in a wingless immature stage called a nymph. They have complex life cycles and may have more than one host plant. They can also winter above ground in the crevices of bark on trees in the egg stage. Unmated females give birth to live crawlers in the spring which are highly active and disperse throughout the tree. Winged males emerge and mate with females in the fall.
Management Recommendations
Conserve the natural enemies that protect your tree from other pests by applying horticultural oil in the spring to kill overwintering aphids on twigs. If aphids are seen later in season,an application of insecticidal soaps or summer oils, or neem can be helpful. Broad spectrum contact insecticides like bifenthrin can kill more aphids, but may foster outbreaks of spider mites later in the season. To protect bees, do not apply foliar insecticides when bees are flying to flowers. Use varieties of trees grafted onto resistant root stocks in areas with a history of high populations of woolly apple aphid to avoid problems. When insecticides are needed, avoid using long lasting broad spectrum materials when natural enemies have been detected. Application of alternative insecticides like insecticidal soaps or horticultural oils can kill large numbers of aphids while allowing natural enemies to re-colonize aphid infestations after these materials have dried.
Effective Pesticides
Active Ingredients include: Bifenthrin, Cyfluthrin, Horticultural oils, Insecticidal soap (Potassium salt of fatty acid), Neem oil, Permethrin
