Pear Rust Mite

family: eriophydiae
species: epitrimerus pyri
common names: pear rust mite
antennae characters: none
specialties: looks like minute conic slug
hosts: pears
natural enemies: predatory mites
pesticides used: oil-based miticides; use of pyrethroids causes 2ary outbreaks by killing off natural enemies
notes: cosmetically scars fruit, may be alternate food for predator to help them build numbers so they can control tetranychids. Aculus schlechtendali & Calepitumerus baileyi are similar mites that attack apple

Agriculture and Agri-Food Canada Insect Identification Sheet No. 67 April 1983

Rust Mites

There are four species of rust mites of economic importance on orchard trees across Canada. They are pests of apples, pears, cherries and plums.

Injury:

Apple rust mites feed on both surfaces of host tree leaves, causing them to turn brown and dry. The first symptom of infestation is an upward curling of the leaf. Severe infestation can result in all the leaves turning brown. Plum rust mites cause circular yellow spots (pinpoint to 2 mm in diameter) on leaves, and larger oval spots on twigs. A leaf with as many as 50 spots may become twisted and wavy. Heavy infestations can keep leaves from expanding to full size. Pear rust mites feed on the leaves and fruit, causing browning of foliage and russeting on the skin of the fruit. Badly russeted fruit are not suitable for fresh marketing and the skin is difficult to remove for canning.

Life History:

Rust mites are elongate, fusiform, pale to brownish-yellow, and extremely small (0.25 mm). Specialized deutogyne females overwinter in crevices in tree bark or in small cracks on twigs. When the buds begin to open they move to feed on the foliage if they are apple or plum rust mites, or on the bud scales if they are pear rust mites. The flattened elliptical eggs are laid on leaves and bud scales. Eggs hatch in 2 to 15 days, depending on the temperature. The mites attain maturity as males and protogyne females in 2 to 18 days, having gone through a larval and a nymphal stage. There may be more than one generation per year, with populations being greatest in June and July. Numbers decline in August when deutogynes are produced that migrate to overwintering sites.

Pest Management:

Apple and plum rust mites are usually controlled through predation. If pesticides are necessary, they should be applied during the summer. Pear rust mites are best controlled by spraying during the pink or calyx stage. Contact your provincial Department of Agriculture for further control recommendations.

Written under contract to the BC Ministry of Environment, Lands and Parks (now Ministry of Water, Land and Air Protection) by: D.E. Henderson, E.S. Cropconsult Ltd., Vancouver, British Columbia in collaboration with D.A. Raworth, Research Station, Vancouver, British Columbia:

On the west coast an eriophyid mite called the redberry mite (Acalitus essigi (Hassan)) can be of importance in raspberry crops. The mites are microscopic; they spend the winter in the buds and feed on the developing fruit during spring and summer. Affected druplets remain hard and sour after the fruit is ripe. Predatory mites are of some value in controlling this pest.