P&PDL Picture of the Week for
November 17, 2008

Cedar Quince Rust on Hawthorne Masquerades as Insect Galls

Gail Ruhl, Plant Disease Diagnostician, Purdue Plant and Pest Diagnostic Laboratory

Cedar quince rust causes damage to ornamental rosaceous hosts, especially to hawthorns. Symptoms include extensive, unsightly, stunted, distorted fruit and swollen stem infestations that become covered with orangish-pink spore horns during the growing season (Figures 1, 2a, 2b). Extensive galling causes branch dieback and a decline in overall tree health. During the ‘dormant’ season, when the powdery rust fungus is not present, stem and fruit distortions are often mistaken for old insect galls (Figures 3a, 3b, 3c).

Now is a good time to inspect the bare branches of your hawthorns to prune out and discard branch tissue with rust galls.

Please refer to BP-137,Cedar Apple and Related Rusts on Landscape Plants (pdf file) for additional information.

Click image to enlarge

Cedar quince rust

Figure 1

Cedar quince rust

Figure 2A

Cedar quince rust

Figure 2B

Insect gall

Figure 3A

Insect galls

Figure 3B

Insect galls

Figure 3C

Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service