P&PDL Picture of the Week for
April 10, 2006

Wooly Apple Aphid--A Galling Experience for Crabapples

Gail Ruhl, Sr. Plant Disease Diagnostician, Department of Botany & Plant Pathology, Purdue University
Tim Gibb, Insect Diagnostician, Department of Entomology, Purdue University

Wooly apple aphids have produced gall-like growths on the branches of this crabapple tree. Heavy populations can cause decline. Often damage can be more severe underground on roots than it is on the trunk and branches. While wooly apple aphid is not a common problem, it is often promoted through continual applications of pyrethroid insecticides that kill off natural enemies.

An application of dormant oil in mid April (making sure that temperatures both 2 days before and 2 days after application are above 45 degrees) and a follow-up late season application of an insecticide labeled for aphid control on crabapple should assist in management of this insect problem.

Note--always read and follow all label directions when using pesticides. It is illegal to use any pesticide in a manner that is not consistent with the product label.

 

Click image to enlarge

Gall-like damage on crabapple branch due to wooly apple aphids

Gall-like damage on crabapple branch due to wooly apple aphids

Wooly apple aphid infestation on branches of young crabapple tree

Wooly apple aphid infestation on branches of young crabapple tree

 

Wooly apple aphids living within damaged branch tissue

Wooly apple aphids living within damaged branch tissue

Close-up of wooly apple aphids

Close-up of wooly apple aphids

Root galls caused by wooly apple aphids

Root galls caused by wooly apple aphids

Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service