Pear trees sometime develop distinctive discoloured blotches on their leaves during the spring and summer. This is a sign of a pear blister mite infestation.
What is pear blister mite?
Pear blister mite is a microscopic pest that feeds on the foliage of pear trees.
Similar mites can be found on Sorbus and other Rosaceae trees, but these are different species to that found on pear.
Pear trees suffering from blister mite will look as follows;
- In spring, the new foliage develops many slightly raised blisters, up to 3-4mm in diameter, that are reddish pink or yellowish green in colour
- Later in the summer, these blister become blackish brown
In light infestations it may be worthwhile removing infested leaves or shoots to stop the pest spreading all over the tree. However, taking infested leaves off a heavily affected tree will do more harm than good.
There are currently no pesticides available to amateur gardeners that are effective against this mite, so its presence has to be tolerated.
Fortunately, although heavily infested trees may look unhealthy, the mite has little impact on the tree’s ability to produce fruit.
The mites overwinter underneath the outer bud scales on pear trees.
In spring, the mites emerge and penetrate into the developing foliage. They feed by sucking sap from the leaf cells and while doing so, they secrete chemicals that create small discoloured blisters around where the mites are feeding.
The mites spend the summer feeding and breeding inside the leaves but come out and to seek overwintering sites before leaf fall.
Common name Pear blister mite
Latin name Eriophyes pyri
Plants affected Pear
Main symptoms Many slightly raised pink or yellowish green blotches on the foliage in spring, later becoming blackish brown
Caused by A microscopic gall mite