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Ministry of Agriculture, Food and Rural Affairs

European Red Mite

European red mite female and eggs Overwintering ERM eggs on spur
Click to enlarge.

Beginner

This pest affects:

Scientific Name
Panonychus ulmi (Koch)

Identification 
Eggs

  • Red
  • Slightly flattened (onion-shaped)
  • Hair-like stalk protruding from the top

Nymphs

  • Newly hatched nymphs have three pairs of legs
  • Older nymphs have four pairs of legs
  • Typically reddish, but may appear green following molting
  • 0.15-0.4 mm, depending on life stage

Adults

  • Female - 0.40 mm long deep brown-red, with rows of spots on her back with raised “spines”
  • Male - 0.28 mm long, lighter or drabber in colour with a pointed abdomen, and legs proportionately longer than the female

Damage

  • Stippling and bronzing on the leaves, especially along the main veins
  • Severe infestations may result in necrosis, leaf burn, and defoliation especially in pear
  • Leaf burn in pear can even occur after mites have been controlled if high temperatures follow feeding dam­age
  • Fruit colour, soluble solids, firmness, size and weight of the fruit are also affected
  • In severe cases, mite-induced tree stress may result in branch dieback and even death during harsh winters
  • Decreased yield the year after significant June and July infestations because fewer fruit buds are formed
  • As well as damaging foliage, spider mites feed on the epidermis of pear fruit, causing russeting. High populations late in the season are most likely to cause fruit russet
  • Mites are often most troublesome during the harvest period by being a nuisance or irritant to pickers

Often Confused With
Two-spotted spider mite- infestation associated with extensive webbing; Damage from both mites appear as a bronzing of the leaves. Although they belong to the same family as two-spotted spider mites, European red mites produce less obvious webbing

Powdery mildew on cherry leaves -

Period of Activity
Active European red mites are present from prior to bloom to harvest. The first few generations are generally synchronous in development, but by mid summer, generations overlap and all stages (eggs, nymphs, adults) are present at the same time. Females begin laying winter eggs in late August on twigs, branches and in the calyx end of fruit on pears.

Mites typically do not become abundant and injurious to peach and nectarine until mid-to-late summer.

Scouting Notes
Begin weekly monitoring programs for European red mites in the dormant stage of tree development. Examine fruit spurs and/or twigs for overwintering mite eggs. From tight cluster through to petal fall, collect 2 fruit spurs from 25 random trees per block and examine the underside of the leaves using a dissecting microscope with a magnification of 25-40X for the presence of mite eggs, nymphs, adults and beneficial mites. Using a hand lens in the field may help experienced consultants and scouts obtain quick estimate of numbers, but does not provide accurate counts required for threshold numbers.    

After petal fall, collect 2 leaves from each of 25 well-spaced trees per block (50 leaves total). Pick leaves at arm’s length into the canopy. Include European red mite and two spotted spider mites in counts –total the number of mite eggs, nymphs and adults.

Sample leaves on a weekly basis, especially during hot summer months when numbers can increase and exceed thresholds very quickly. Although mites commonly occur in greater numbers on trees in sheltered areas and next to dusty roadways, always sample equally from all parts of blocks.

Take separate samples for each orchard block or treatable area. Some cultivars could support larger mite populations compared to others. Sample these, along with orchard blocks with a history of mite problems. 

Beneficial mites can delay or prevent the need for a miticide application, so be sure to note their presence during monitoring.

Thresholds
Pears can be badly damaged by even small populations so a miticide should be applied at first sign of mite activity on branches closest to scaffold limbs and foliar symptoms and 2-5 mites per leaf.  There are no set thresholds for ERM on apricots, sour cherries, peaches, nectarines or plums.  Tolerance to damage by ERM will depend on tree health and stresses such as drought.

 

Advanced

This pest affects:

Scientific Name
Panonychus ulmi (Koch)

Identification 
Eggs

  • Red
  • Slightly flattened (onion-shaped)
  • Hair-like stalk protruding from the top

Nymphs

  • Newly hatched nymphs have three pairs of legs
  • Older nymphs have four pairs of legs
  • Typically reddish, but may appear green following molting
  • 0.15-0.4 mm, depending on life stage

Adults

  • Female - 0.40 mm long deep brown-red, with rows of spots on her back with raised “spines”
  • Male - 0.28 mm long, lighter or drabber in colour with a pointed abdomen, and legs proportionately longer than the female

Damage

  • Stippling and bronzing on the leaves, especially along the main veins
  • Severe infestations may result in necrosis, leaf burn, and defoliation especially in pear
  • Leaf burn in pear can even occur after mites have been controlled if high temperatures follow feeding dam­age
  • Fruit colour, soluble solids, firmness, size and weight of the fruit are also affected
  • In severe cases, mite-induced tree stress may result in branch dieback and even death during harsh winters
  • Decreased yield the year after significant June and July infestations because fewer fruit buds are formed
  • As well as damaging foliage, spider mites feed on the epidermis of pear fruit, causing russeting. High populations late in the season are most likely to cause fruit russet
  • Mites are often most troublesome during the harvest period by being a nuisance or irritant to pickers

Often Confused With
Two-spotted spider mite- infestation associated with extensive webbing; Damage from both mites appear as a bronzing of the leaves. Although they belong to the same family as two-spotted spider mites, European red mites produce less obvious webbing

Powdery mildew on cherry leaves -

Biology
Overwintering European red mite eggs are usually found on roughened bark around the base of buds and spurs, and in the inner parts of the tree close to the main trunk and branches. Eggs begin to hatch around the tight cluster stage of pears or at shuck for tender fruit such as peaches and nectarines.  Extreme winter weather or adverse conditions during hatch can negatively affect survival of overwintering European red mite eggs.

Immature mites feed primarily on the lower surface of the leaf near the veins and midrib. Adults feed on both the upper and lower surfaces of the leaf. Feeding on leaves causes characteristic leaf injury referred to as bronzing. Mites insert their needle-like mouthparts into leaf cells and suck out cell contents, including chlorophyll. Mites prefer to feed on succulent tissues and fecundity increases when trees have vigorous high-nitrogen containing growth.

As eggs hatch, nymphs move from the twigs to developing foliage where they begin feeding. Nymphs eventually become adults that mate and lay the first generation of “summer eggs.” There can be six to eight generations of European red mite each year. The rate of development is temperature dependent, being slower in the spring and fall, and more rapid during the hot summer months. The first generation generally requires about 3 weeks to develop from egg to adult, while summer generations may develop in 10 to 14 days. Hot dry conditions are conducive to severe mite infestations; however, temperatures above 30°C negatively affect egg laying and development. Heavy rain can physically remove many mites.

Natural enemies of mites include predatory mites and predators such as Stethorus punctillum, minute pirate bugs (Orius spp.), predatory thrips, lacewings and mullein bugs Campylomma verbasci.

Period of Activity
Active European red mites are present from prior to bloom to harvest. The first few generations are generally synchronous in development, but by mid summer, generations overlap and all stages (eggs, nymphs, adults) are present at the same time. Females begin laying winter eggs in late August on twigs, branches and in the calyx end of fruit on pears.

Mites typically do not become abundant and injurious to peach and nectarine until mid-to-late summer.

Scouting Notes
Begin weekly monitoring programs for European red mites in the dormant stage of tree development. Examine fruit spurs and/or twigs for overwintering mite eggs. From tight cluster through to petal fall, collect 2 fruit spurs from 25 random trees per block and examine the underside of the leaves using a dissecting microscope with a magnification of 25-40X for the presence of mite eggs, nymphs, adults and beneficial mites. Using a hand lens in the field may help experienced consultants and scouts obtain quick estimate of numbers, but does not provide accurate counts required for threshold numbers.    

After petal fall, collect 2 leaves from each of 25 well-spaced trees per block (50 leaves total). Pick leaves at arm’s length into the canopy. Include European red mite and two spotted spider mites in counts –total the number of mite eggs, nymphs and adults.

Sample leaves on a weekly basis, especially during hot summer months when numbers can increase and exceed thresholds very quickly. Although mites commonly occur in greater numbers on trees in sheltered areas and next to dusty roadways, always sample equally from all parts of blocks.

Take separate samples for each orchard block or treatable area. Some cultivars could support larger mite populations compared to others. Sample these, along with orchard blocks with a history of mite problems. 

Beneficial mites can delay or prevent the need for a miticide application, so be sure to note their presence during monitoring.

Thresholds
Pears can be badly damaged by even small populations so a miticide should be applied at first sign of mite activity on branches closest to scaffold limbs and foliar symptoms and 2-5 mites per leaf.  There are no set thresholds for ERM on apricots, sour cherries, peaches, nectarines or plums.  Tolerance to damage by ERM will depend on tree health and stresses such as drought.

Management Notes
Bartlett is more tolerant to leaf burn and defoliation than D’Anjou and Bosc.

Maintain well-managed cover crops between rows to limit dusty conditions that favour a buildup of pest mites.

Management with miticides – In orchards with a history of mite pressure, miticides are used tto control European red mite. For information on the timing of specific miticides, see OMAFRA Publication 360, Fruit Crop Protection Guide:

Chapter 5 Apricot Calendar: Recommendations for European red mite at Dormant , Special sprays
Chapter 5 Peach Calendar: Recommendations for European red mite at Prebloom, Shuck split to shuck fall, Special sprays

Chapter 5 Pear Calendar: Recommendations for European red mite at Green tip, White bud, Petal fall, Summer sprays

Chapter 5 Plum Calendar: Recommendations for European red mite at Green tip
Chapter 5 Sour Cherry Calendar: Recommendations for European red mite at Prebloom, Shuck split, Special Sprays second cover, Special sprays third Cover

Some information included aboce excerpted from;