Disease on Pussy Willow plant - Knowledgebase Question

west caldwell, Ne
Question by hsp7
July 3, 2010
My pussy willow tree/bush is having some sort of growth on all the leaves. I cut down all the branches 2 years ago and it got better but this year the growth came back with a vengence. I think the growth on the leaves, which is white color, is some sort of egg mass. What can I do about it short of cutting down the whole plant?


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Answer from NGA
July 3, 2010

0

The willow blister gall is a grayish-white and red, somewhat round and fuzzy growth on the upper and lower surfaces of willow leaves, especially pussy willow.

The galls are caused by a tiny mites called eriophyid mites. Eriophyid mites are microscopic and rather carrot-shaped. They spend the winter on the willow bark and branches and in the spring they come out of hibernation to move to the developing leaves. Their feeding and presence on the tender leaves causes the leaf edges to swell, wrinkle and curl over to form a protective chamber. Additional pouch-like galls may occur on the entire leaf surface. The summer is spent feeding and reproducing. When large numbers of eriophyid mites develop, willow leaves may become completely curled and badly distorted.

In general, plant galls are not a serious threat to the life of a plant. They do cause some unsightliness when large numbers appear. Controls are not normally recommended for willow galls.

Simply prune out the willow beaked-galls as they are noticed. If these are pruned out in the fall or winter, be sure to destroy them by crushing or burying. The adults will probably still emerge even if the galls are simply thrown to the ground. There are no registered chemicals for control of the mites that cause the galls.

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