Pests and Diseases Viewer

Mountain Ash Blister Mite


Mountain Ash Blister Mite

Usually appear in

Spring to Autumn.

Back to Pests and Diseases

Caused By:-     The Mite Phytoptus pyri(Eriophyes Pyri)


The Mountain Ash Blister Mite is the same mite that causes pear Leaf Blister Mite(Phytoptus pyri previously Eriophyes Pyri). This mite is also causes problems on Apple, Pear, Quince, Hawthorn and Cotoneaster and other related species. The bodies of these mites are elongate and wormlike. The body length is 1/100 inch (200-240 microns; 0.2 mm). Therefore these will only be seen with a compound microscope. While in the bud, mites are white; later in the season they assume a pinkish colour. The mite is the cause of the numerous pale blister-like galls on the leaves of these trees. Each leaf galls are each caused by a single minute mite which enters the leaf by the stomata or breathing pores. Where they breed in the leaf tissues. The galls turn black later, and the whole leaf may die or more usually falls off. Young fruitlets are also attacked and ruined by small reddish blister-like galls being formed on them. Once inside the females begin to lay eggs which will repeat the cycle 3 to 3 times a year. Activity ceases during June, July and August, resuming when cool evenings return. Mites enter bud scales from September to November. where they over-winter . As soon as the buds breaks in the Spring they attack the leaves or blossoms and enter the tissue.


Spraying with a systemic insecticide or oils will help, but the main way to eradicate this pest is doing a winter wash with insecticidal oils in the dormant period. Usually the infestation is not excessive and can be tolerated as the vigour of the tree is not affected.

Back to top