Buckeye Yard and Garden onLine

The round to oblong-shaped hackberry petiole galls are light-green to greenish-yellow and measure 1/2" in diameter. They occur near the base of the leaf blade and leaves may become distorted as they are incorporated into the gall structure. The galls provided a brief lesson regarding gall-terminology. The petiole galls are plurilocular, meaning that there are multiple chambers in each gall, as opposed to unilocular which means there is only one chamber per gall. And, the galls are unilarval, meaning that each chamber houses a single gall-making psyllid nymph as opposed to multilarval which means gall chambers house more than one immature gall-maker.

Mossy rose galls are huge, spherical, hairy-looking structures that arise from year-old rose stems and measure as much as 2" in diameter. The galls appear on the stems in June or July. A close examination will reveal that the "hairs" are actually tendrils that are covered with short spikes. The tendrils are light green at first, but they quickly become much more colorful with the green becoming deep red accented by pink overtones. The plurilocular, unilarval galls may house 10-20 wasp larvae.

The rose galls cause little harm to the overall health of rose plants; however, a heavy infestation may detract from plant aesthetics. Old galls turn an unsightly grayish-brown and can take 1 - 2 years to degrade and disappear. Since the wasp larvae spend the winter in the galls, pruning to remove the galls in the fall or very early spring provides an effective control by reducing wasp populations in rose plantings.