GardenLine | Yard & Garden | Spiny Rose Gall

Galls are abnormal plant growths resulting from activity of the tiny, non-stinging cynipid wasps - (Diplolepis bicolor).

Rose galls occur on leaves or stems of the rose plant and are specific to the species of gall maker. The spiny rose gall is round with many pink spines. Insect larvae develop inside the gall. Stem galls can damage plants above the location of the gall, especially if there are many galls on a particular stem. Numerous galls may stress the plant because nutrients otherwise available for plant growth are used to produce galls.

Control: The recommended control is to prune galls before the wasps have matured and emerged. Since adults emerge from the old galls in spring, prune out the galls after the leaves drop in fall, cutting below the gall and above a bud. For leaf galls, pick up fallen leaves. Removing the galls from the garden will not eliminate future problems if adult wasps fly in from nearby areas.

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Sustainable horticultural information, offered free of charge to the public with the support of the University of Saskatchewan Extension Division, the Department of Plant Sciences and the Provincial Government.