Pear Rust Mite
Beginner
This pest affects:
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Scientific name
Epitrimerus pyri
Identification
Eggs
- Clear to white in colour
- Spherical, 0.05mm in length
- Resemble the adults, 0.07mm in length
Adults
- Yellowish brown, 0.05mm in length
- Body is wedge shaped, tapering at posterior end
- Two pairs of legs attached just behind the head
Damage
Leaves
- Feeds first on green tissue at bud base, later moves to foliage or fruit
- Leaves turn brown or bronze, can lead to defoliation and reduced shoot growth in young tree
Fruit
- Early season light russetting at the calyx or the stem, can cover entire fruit surface as the season continues
- Extreme russetting of fruit surface can occur, leaving fruit rough and brown. Most obvious on clear-skinned pears, such as Bartlett, Anjou and Comice. Naturally russeted cultivars, such as Bosc and red-skinned varieties seem more tolerant to rust mite damage
Often confused with
Pear Blister Mite – depressed russet spots and deformed fruit; galls and green/red blisters on leaves
Period of activity
White bud to mid-summer, through harvest if hot, dry temperatures persist.
Scouting Notes
Because of its small size, spotty distribution and low injury threshold, it is very difficult to monitor pear rust mite for the purpose of relating population density to potential damage.
Examine 50 fruitlets from 10 trees 10-14 days after petal-fall for russeting on calyx ends of fruit. Repeat this after two weeks. Later in the season, pear rust mite can be monitored using leaf samples taken to monitor pear psylla and/or fruit samples.
Thresholds
If pear rust mite is detected at all in the prebloom and bloom period, it must be controlled.
After petal fall (Summer Sprays) control is needed when mites or russeting are found on 5 or more fruitlets in 50.
Advanced
This pest affects:
|
Scientific name
Epitrimerus pyri
Identification
Eggs
- Clear to white in colour
- Spherical, 0.05mm in length
- Resemble the adults, 0.07mm in length
Adults
- Yellowish brown, 0.05mm in length
- Body is wedge shaped, tapering at posterior end
- Two pairs of legs attached just behind the head
Damage
Leaves
- Feeds first on green tissue at bud base, later moves to foliage or fruit
- Leaves turn brown or bronze, can lead to defoliation and reduced shoot growth in young tree
Fruit
- Early season light russetting at the calyx or the stem, can cover entire fruit surface as the season continues
- Extreme russetting of fruit surface can occur, leaving fruit rough and brown. Most obvious on clear-skinned pears, such as Bartlett, Anjou and Comice. Naturally russeted cultivars, such as Bosc and red-skinned varieties seem more tolerant to rust mite damage
Often confused with
Pear Blister Mite – depressed russet spots and deformed fruit; galls and green/red blisters on leaves
Biology
Found on cultivated pears, wild pear and quince.
The pear rust mite overwinters as an adult female under leaf scars, bud scales or in small cracks usually on 2- to 3-year-old wood. Once the warm weather breaks (even if before bud break), the mites feed and lay eggs under the bud scales. As the blossom cluster expands to shed the outer scales, the exposed mites migrate toward the developing bloom Once the mites hatch, they begin feeding on the flower stems just before bloom. The pear rust mite passes rapidly through two nymphal stages. By petal fall, the mites are feeding on leaves and at the calyx end of the developing fruit. Hot dry weather causes a rapid build-up of mites, taking only 10-14 days for a generation to complete under ideal conditions. There are 2-3 generations per year.
Russetting begins to appear in June, and usually appears on the south or east side of the tree. If not controlled, the entire fruit may have russetting.
By late summer, only females are present and they begin to seek overwintering sites. However, if it continues to be hot and dry, the mites will continue feeding until the colder weather occurs.
Period of activity
White bud to mid-summer, through harvest if hot, dry temperatures persist.
Scouting Notes
Because of its small size, spotty distribution and low injury threshold, it is very difficult to monitor pear rust mite for the purpose of relating population density to potential damage.
Examine 50 fruitlets from 10 trees 10-14 days after petal-fall for russeting on calyx ends of fruit. Repeat this after two weeks. Later in the season, pear rust mite can be monitored using leaf samples taken to monitor pear psylla and/or fruit samples.
Thresholds
If pear rust mite is detected at all in the prebloom and bloom period, it must be controlled.
After petal fall (Summer Sprays) control is needed when mites or russeting are found on 5 or more fruitlets in 50.
Management notes
Apply miticides as a dilute spray from both sides.
Avoid excessive applications of mineral sprays destructive to predators.
Pear rust mite has a few natural controls, including predaceous mites, green and brown lacewings, lady beetles; however, it is shown that this is not enough to control the pest.
Management with insecticides – Insecticides are used to control pear rust mite in commercial orchards with a history of pressure. OMAFRA Publication 360, Fruit Crop Protection Guide.
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Chapter 5 - Pear calendar: Recommendations for pear rust mite at White bud, , Petal fall, Summer sprays. |
Some information included above excerpted from;
