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Ministry of Agriculture, Food and Rural Affairs

Leafrollers

Leafroller damage to young orchards Aborted fruitlet from early season caterpillar feeding Early season damage at harvest Late season injury to fruit
Click to enlarge.

Beginner

Scientific Names
Redbanded leafroller, Argyrotaenia velutinana (Walker), variegated leafroller, Platynota flavedana (Clemens), fruit tree leafroller, Archips argyrospila (Walker), and obliquebanded leafroller, Choristaneura rosaceana (Harris)

Identification
Eggs:

  • Found on the upper surface of leaves,
  • Flattened, overlapping clusters of 20-200,
  • Pale yellow to brownish eggs.

Larvae:

  • Fruit tree leafrollers - light to dark green with a black head, larvae wriggles backward when disturbed,
  • Redbanded leafrollers are pale-headed, greenish, active caterpillars that measure 16 mm at maturity,
  • Variegated leafroller larvae are green with a light brown of armber head capsule ; the sides of the body are lighter green than the top,
  • Obliquebanded leafroller have a light to dark green body with a dark brown or black head.

Damage:

  • Webbing and rolling of young terminal leaves,
  • Corky scars and indentations on fruit – which often drops prematurely,
  • Most severe around the orchard periphery and adjacent to woodlots.

Often Confused With

  • Bird pecking – Damage on fruit is often confused with bird pecking.
  • Obliquebanded leafroller – To distinguish the obliquebanded leafroller from other leafrollers, look for dark brown or black head capsules and green bodies.

Period of Activity
Leafroller larvae become active as soon as green tissue is visible, and some (obliequebanded leafroller, variegated leafroller, redbanded leafroller) can be found in orchards up until harvest.

Scouting Notes
Leafrollers are general feeders, consuming leaves of many species of fruit and shade trees. They are most often detected in apple trees at the perimeter of the orchard adjacent to alternative hosts but do not restrict monitoring to orchard perimeters.

In early spring, tiny larvae in buds and developing terminals are difficult to detect without pulling the plant tissue apart and observing with a 10-16X hand lens. During the period between tight cluster to petal fall, check 5 terminal shoots and 5 fruit buds in each of 10 trees (50 terminals and 50 fruit buds in total) for signs of caterpillar feeding activity. After petal fall insect 10 terminals from 10 trees for the presence of larvae.

Thresholds
An insecticide is generally recommended when the action threshold of 12-15 larvae per 100 terminals and fruit buds is observed (see the infosheet on obliquebanded leafroller for specific threshold).  

Advanced

There are numerous species of leafrollers belonging to a family of moths called Tortricidae that attack apple. The leafroller currently causing the greatest concern in Ontario is the obliquebanded leafroller (see infosheet on obliquebanded leafroller for more information).

Scientific Names
Redbanded leafroller, Argyrotaenia velutinana (Walker), variegated leafroller, Platynota flavedana (Clemens), fruit tree leafroller, Archips argyrospila (Walker), and obliquebanded leafroller, Choristaneura rosaceana (Harris)

Identification
Eggs are found on the upper surface of leaves in flattened, overlapping clusters of 20-200 pale yellow to brownish eggs. Fruit tree leafrollers are light to dark green with a black head, larvae wriggles backward when disturbed. Redbanded leafrollers are pale-headed, greenish, active caterpillars that measure 16 mm at maturity.Variegated leafroller larvae are green with a light brown of armber head capsule; the sides of the body are lighter green than the top. Obliquebanded leafroller have a light to dark green body with a dark brown or black head.

Leafrollers become active as soon as green tissue is visible, feeding on young developing leaves or boring into buds. As the leaves expand, larvae begin to web and roll terminal leaves. Early season feeding causes large corky scars and indentations on the fruit – which often drops prematurely. Summer feeding on developing fruit results in downgrading of apples to juice quality. Some leafroller species suspend themselves from silken threads, allowing them to disperse to other trees with the slightest breeze. Infestations are often most severe around the orchard periphery and adjacent to woodlots.

Often Confused With

  • Bird pecking – Damage on fruit is often confused with bird pecking.
  • Obliquebanded leafroller – To distinguish the obliquebanded leafroller from other leafrollers, look for dark brown or black head capsules and green bodies.

Biology
Most leafroller species overwinter as larvae in hibernacula or as pupae. However, the fruit tree leafroller overwinters as an egg. There are two generations of most leafroller species. Female moths lay eggs on the upper surface of leaves. Leafrollers become active and feed on leaves and buds. Leaf feeding, if severe, can reduce photosynthetic activity.  Leafrollers quickly become a major problem in nursery plantings and newly planted orchards if not controlled.

Period of Activity
Leafroller larvae become active as soon as green tissue is visible, and some (obliequebanded leafroller, variegated leafroller, redbanded leafroller) can be found in orchards up until harvest.

Scouting Notes
Leafrollers feed on a wide variety of deciduous trees and shrubs, herbaceous plants and brambles. They are most often detected in apple trees at the perimeter of the orchard adjacent to alternative hosts. Many species are also dispersed deeper into the orchard interior by wind currents, so do not restrict monitoring to orchard perimeters.

In early spring, tiny larvae in buds and developing terminals are difficult to detect without pulling the plant tissue apart and observing with a 10-16X hand lens. 

During the period between tight cluster to petal fall, check 5 terminal shoots and 5 fruit buds in each of 10 trees (50 terminals and 50 fruit buds in total) for signs of caterpillar feeding activity. After petal fall inspect 10 terminals from 10 trees for the presence of larvae.

Thresholds
An insecticide is generally recommended when the action threshold of 12-15 larvae per 100 terminals and fruit buds is observed (see the infosheet on obliquebanded leafroller for specific threshold).

Management Notes

  • Many predatory and parasitic insects attack spring-feeding caterpillars. Predators include ground beetles (Carabidae), stink bugs (Pentatomiidae), assassin bugs (Reduviidae) and spiders. However, beneficial insects are not usually effective in providing economic control.
  • To conserve and encourage natural enemies of spring-feeding caterpillars, apply insecticides only if the action threshold is reached and then select the most benign and narrow-spectrum materials available. For information on the toxicity of pesticides to beneficial insects click here.
  • Birds such as chickadees, bluebirds, warblers and woodpeckers also feed on caterpillars, however they do not provide adequate control.
  • Parasitic wasps (Braconidae, Ichneumonidae) and flies (Tachinidae) attack caterpillars and minute Trichogramma wasps often parasitize moth eggs.
  • A number of fungal and viral diseases also impact caterpillar populations, particularly during warm, wet springs.
  • Depending on spring temperatures, timing of this spray may occur either pre-bloom (usually at pink) or at petal fall.
  •  Insecticide options are provided in OMAFRA Publication 360, Guide to Fruit Production - Chapter 3 Apples (PDF) or Apple Calendar only (PDF) :