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Beginner

This pest affects:

;

Scientific Name
Conotrachelus nenuphar

Identification 
Eggs

• 0.6 mm long, white and elliptical
• Deposited under the fruit skin

Larvae

• Cream-coloured, with a distinct brown head capsule
• C-shaped and legless
• Four instars, with mature larvae reaching 6-9 mm long

Pupae

• 5–7 mm long
• White or cream coloured, and soil dwelling

Adults

• 4-6 mm long
• Dark brown with grey and white dorsal patches
• Bent antennae arise from an elongated beak-like snout
• Four distinctive humps on their elytra (wing covers)

Damage:

• Females create crescent-shaped oviposition scars or feeding scars which remain on the fruit until harvest.  These injuries can result in distorted growth of fruit (cat-facing).  Damaged fruit remaining on the tree have crescent shaped scars  bumps that protrude from the fruit and malformed and unsuitable for fresh market sale
• Internal larval injury will cause fruit to prematurely ripen and typically drop during June drop period or later in the season
• Larvae hatching from the eggs feed inside the fruit until they are fully grown. When the larvae is finished feeding on the fruit, it leaves by a clean hole in the side of the fruit
• Fresh damage often has sap oozing out of the wound

Often Confused With
Other weevils - The presence of four distinctive humps on their elytra (wing covers) helps distinguish adults from other weevils

Cherry fruit fly larvae - White, legless maggot-like with no distinct head

Codling moth: larvae have legs and usually tunnel directly to the seed cavity and feed on the fruit seeds.  There will be a clearly defined entry hole into the fruit usually with frass present

Oriental fruit moth:  larvae have prolegs and anal comb and tunnel into and feed on the flesh of the fruit from the calyx or stem ends.  There will be a clearly defined entry hole into the fruit usually with frass present.
Hail: following severe weather, usually occurring on windward side of tree/fruit.  Leaves will be torn or ripped and damaged areas on fruit will have a depression or bruise

Period of Activity
Warm temperature (above 16 °C) following a rain is ideal for plum curculio emergence Expect emergence if mean temperature is 13-16 °C for 3 to 4 days, mean above 16 °C for 3 days, or if over 24 °C for 2 consecutive days and high soil moisture levels. Emergence can occur over a 4-6 week period.

	Pear: Plum curculio adults begin to migrate into orchards from white bud through petal fall. Adults do not begin to damage fruit until after petal fall and can continue until the beginning of summer.
	Stone Fruit: Adults migrate into the orchard during a 4-6 week period beginning around the shuck stage. Plums and nectarines are chosen as egg-laying sites by the overwintering generation more frequently than are peaches.

Plum curculios adults begin to lay eggs shortly after the shuck split stage on stone fruit, but the peak of egg-laying is not reached until most of the shucks have fallen and the fruit is beginning to size.

Scouting Notes
The best way to limit PC damage is to set up a rigorous monitoring program in areas with previous damage. PC is quite sporadic and often confined to border areas. When conditions are right in the spring, fruit should be examined by counting a minimum of 200 fruit per block for egg-laying scars or feeding injury. Fresh damage often has sap oozing out of the wound.  

	Pears: Monitor wild fruit trees (plums) adjacent to or near orchard perimeters for feeding and oviposition scars beginning at bloom.  Examine trees in border rows every two to three days after petal fall until the beginning of summer for signs of fresh injury.
	Stone fruit: Apricots, cherries and plums located along borders of an orchard are good indicator plants for PC activity. Observe fruit along the outside two to three rows of the orchard next to wild hosts. Monitoring of PC in stone fruit should be concentrated from petal fall through two weeks after shuck-fall for the signs of damage.

Thresholds
No economic threshold levels have been established. However since PC is a direct pest, no more than 1/2 to 1 percent fruit injury should be tolerated.   Early detection is the key to effective management  Once first injury is detected, apply an insecticide. If subsequent weekly monitoring finds fresh damage, additional sprays may be needed to protect the crop. 

Advanced

This pest affects:

;

Scientific Name
Conotrachelus nenuphar

Identification 
Eggs

• 0.6 mm long, white and elliptical
• Deposited under the fruit skin

Larvae

• Cream-coloured, with a distinct brown head capsule
• C-shaped and legless
• Four instars, with mature larvae reaching 6-9 mm long

Pupae

• 5–7 mm long
• White or cream coloured, and soil dwelling

Adults

• 4-6 mm long
• Dark brown with grey and white dorsal patches
• Bent antennae arise from an elongated beak-like snout
• Four distinctive humps on their elytra (wing covers)

Damage:

• Females create crescent-shaped oviposition scars or feeding scars which remain on the fruit until harvest.  These injuries can result in distorted growth of fruit (cat-facing).  Damaged fruit remaining on the tree have crescent shaped scars  bumps that protrude from the fruit and malformed and unsuitable for fresh market sale
• Internal larval injury will cause fruit to prematurely ripen and typically drop during June drop period or later in the season
• Larvae hatching from the eggs feed inside the fruit until they are fully grown. When the larvae is finished feeding on the fruit, it leaves by a clean hole in the side of the fruit
• Fresh damage often has sap oozing out of the wound

Often Confused With
Other weevils - The presence of four distinctive humps on their elytra (wing covers) helps distinguish adults from other weevils.

Cherry fruit fly larvae - White, legless maggot-like with no distinct head

Codling moth: larvae have legs and usually tunnel directly to the seed cavity and feed on the fruit seeds.  There will be a clearly defined entry hole into the fruit usually with frass present.

Oriental fruit moth:  larvae have prolegs and anal comb and tunnel into and feed on the flesh of the fruit from the calyx or stem ends.  There will be a clearly defined entry hole into the fruit usually with frass present.
Hail: following severe weather, usually occurring on windward side of tree/fruit.  Leaves will be torn or ripped and damaged areas on fruit will have a depression or bruise.

Biology
The plum curculio overwinters as an adult under leaf debris, brush piles and stacked wood near or adjacent to orchards. Adult activity and migration back into the orchard begin in the spring following sustained warm weather (mean temperatures of 15.5ºC or higher) and light rain. This usually occurs around late bloom in pear and lasts for up to six weeks, with the greatest migration occurring within the period of up to 14 days after petal fall. If weather is cool at bloom time and petal fall, adults may not migrate into the orchards until after petal fall. 

Adults mate and feed on developing leaves, blossoms and fruitlets. Females usually lay eggs in the fruit several weeks after emerging, once fruit set has occurred. Females cut a cavity into the fruits’ skin with their snout, depositing an egg in the hole. A crescent-shaped slit cut around the oviposition site helps prevent the egg from being crushed by rapidly expanding fruit.

Eggs hatch in three days at temperatures of 25°C, and may take as long as 12 days to hatch at 18°C. Emerging larvae feed inside the fruit, causing most of the infested pears to drop prematurely. Larvae continue to develop through four instars in fallen fruit. Mature larvae exit fruit and burrow into the soil to pupate. The complete lifecycle from egg to adult takes about 50-55 days. Plum curculio has a single generation a year in Ontario. Early plum varieties with dense foliage and yellow skinned cultivars are most heavily attacked.

Period of Activity
Warm temperature (above 16 °C) following a rain is ideal for plum curculio emergence Expect emergence if mean temperature is 13-16 °C for 3 to 4 days, mean above 16 °C for 3 days, or if over 24 °C for 2 consecutive days and high soil moisture levels. Emergence can occur over a 4-6 week period.

	Pear: Plum curculio adults begin to migrate into orchards from white bud through petal fall. Adults do not begin to damage fruit until after petal fall and can continue until the beginning of summer.
	Stone Fruit: Adults migrate into the orchard during a 4-6 week period beginning around the shuck stage. Plums and nectarines are chosen as egg-laying sites by the overwintering generation more frequently than are peaches.

Plum curculios adults begin to lay eggs shortly after the shuck split stage on stone fruit, but the peak of egg-laying is not reached until most of the shucks have fallen and the fruit is beginning to size.

Scouting Notes
The best way to limit PC damage is to set up a rigorous monitoring program in areas with previous damage. PC is quite sporadic and often confined to border areas. When conditions are right in the spring, fruit should be examined by counting a minimum of 200 fruit per block for egg-laying scars or feeding injury. Fresh damage often has sap oozing out of the wound.  

	Pears: Monitor wild fruit trees (plums) adjacent to or near orchard perimeters for feeding and oviposition scars beginning at bloom.  Examine trees in border rows every two to three days after petal fall until the beginning of summer for signs of fresh injury.
	Stone fruit: Apricots, cherries and plums located along borders of an orchard are good indicator plants for PC activity. Observe fruit along the outside two to three rows of the orchard next to wild hosts. Monitoring of PC in stone fruit should be concentrated from petal fall through two weeks after shuck-fall for the signs of damage.

Thresholds
No economic threshold levels have been established. However since PC is a direct pest, no more than 1/2 to 1 percent fruit injury should be tolerated.   Early detection is the key to effective management  Once first injury is detected, apply an insecticide. If subsequent weekly monitoring finds fresh damage, additional sprays may be needed to protect the crop. 

Management Notes
Prune to open up the canopy and improve spray coverage.

If possible, complete pruning prior to significant green tissue development to allow pruning cuts to heal over.

See OMAFRA Publication 360, Fruit Crop Protection Guide: 

	Chapter 5 Peach Calendar :  Recommendations for plum curculio at Shuck split to shuck fall
	Chapter 5 Apricot Calendar :  Recommendations for plum curculio at Shuck split, Shuck fall, First Cover
	Chapter 5 Plum Calendar :  Recommendations for plum curculio at Shuck fall, First cover
	Chapter 5 Pear Calendar  :  Recommendations for plum curculio at Petal Fall, First Cover
	Chapter 5 Sweet Cherry Calendar :  Recommendations for plum curculio at Shuck fall, First cover, Second cover
	Chapter 5 Sour Cherry Calendar :  Recommendations for plum curculio at Shuck split, First cover, Second cover

Some information included above excerpted from;

• http://www.virginiafruit.ento.vt.edu/PCPeach.html