Pear rust mite
(Epitrimerus pyri)

Overview

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The species Epitrimerus pyri is known as the pear rust mite and is a serious pest to regions of pear production in Canada. This species of pest is sporadic in its presence; however, it can lead to severe damage in instances of high infestation. The pear rust mite over-winters as adult females on the host, becoming active when buds open. As with many mites, they have the ability to produce several generations per year, which makes its management and control more challenging. 

Main description

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The pear rust mite is extremely difficult to see without a hand lens (20X recommended). They are rusty-white to yellow in colour. They have a broad shape at the front and taper in the rear. Infested leaves and fruit will become bronzed and russeted, respectively, in a very short period of time. The mature adult mite only measures 0.17 mm, but the damage produced is apparent in the plant. 

Scouting

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Between 10 days to two weeks after petal-fall, examine 50 fruitlets from 10 trees for russeting on stems and calyx ends. Repeat this after two weeks. Monitor leaves using the same sampling and leaf brushing techniques used for European red mites. If the presence of adults and eggs under the leaves is confirmed, an application should follow soon after to ensure protection. During the application, make sure that cover and full contact underneath the leaves is guaranteed to optimize the speed and efficacy of the treatment.