Pear blister mite

In spring the leaves of pear trees sometimes develop raised pink or yellowish green blotches which usually turn black during the summer. This is a sign of a pear blister mite, it does not normally affect the health or cropping of the tree.

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Pear blister mite

Quick facts

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
Timing April-September

What is pear blister mite?

Pear blister mite is a microscopic mite that feeds within the foliage of pear trees.

Similar mites can be found on Sorbus and other trees in the Rosaceae family, these are different species to that found on pear. As with pear blister mite they have limited effects on the host plant health and can be tolerated. 

Symptoms

Pear trees with blister mite will have the following symptoms;

  • In spring, new foliage develops many slightly raised reddish pink or yellowish green blisters, up to 4mm in diameter
  • Later in the summer, these blisters become blackish brown
  • The whole leaf can be affected and almost all the leaves on a tree may become blackened
  • The mite does not normally affect cropping or the health of the tree and it can be treated as part of the biodiversity these trees support

Control

Although heavily affected trees may look unhealthy, the mite has little impact on the tree’s health or ability to produce fruit and control is not necessary and it can be treated as part of the biodiversity a healthy tree supports.

In light populations leaves or shoots could be removed however taking these leaves off a heavily affected tree may do more harm to the plant than the mite.

Biology

Pear blister mites overwinter underneath the outer bud scales on pear trees.

In spring, the mites emerge and penetrate into developing foliage. They feed by sucking out the contents of the leaf cells and while doing so produce secretions 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.

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