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Stone fruit

Clemson's home-garden guide to peach insects puts plum curculio, oriental fruit moth and peachtree borer at the head of the list, followed by the catfacing bugs (tarnished plant bug and stink bugs) and San Jose scale. Plum curculio cuts crescent-shaped scars in young fruit, and its grubs feed inside. Oriental fruit moth wilts the shoot tips in spring and bores into the fruit later on. Peachtree borer works out of sight under the bark at the base of the trunk, and the first sign is gum mixed with frass.

Of the biological controls you can buy, only one has strong field evidence on stone fruit: nematodes against peachtree borer, which gave 88 % control at 300,000 per tree, and more than 80 % control of larvae already in the tree, in USDA peach-orchard trials. For the rest, the beneficials that matter are wild ones, such as the braconid wasp on oriental fruit moth and the lady beetles on scale. Here the job is to stop killing them with broad-spectrum sprays, and to do the sanitation that Clemson and Kentucky put first: pick up and destroy dropped fruit and dead wood.

crop context · backyard peach tree, fruit set

What attacks a backyard peach, plum or cherry

PETAL FALL TO EARLY SUMMER

Plum curculio

A snout weevil that cuts crescent-shaped scars in the fruitlets; the grub feeds inside and the fruit drops early. Pick up drops before the grubs leave them.

ReleaseEntomopathogenic nematode (supplement)Per package directions — the field trials checked give no home-orchard rate
SPRING SHOOTS, THEN FRUIT

Oriental fruit moth

Larvae bore into peach and nectarine shoot tips, which wilt ("flagging"), then into the fruit. Wilted shoots in early spring warn that later generations may attack the fruit.

ReleaseBraconid waspsNothing to release — avoid broad-spectrum sprays
SUMMER EGG-LAYING, LARVAE ALL YEAR

Peachtree borer

A clearwing moth larva under the bark at the soil line; the tree bleeds gum mixed with frass. A single larva can girdle a newly planted tree.

ReleaseEntomopathogenic nematode300,000 to 1 million infective juveniles per tree at the trunk base (USDA trials)
DORMANT SEASON

San Jose scale

A grey crust on the bark and red-ringed spots on the fruit. Clemson warns scale can kill branches and trees; horticultural oil before bud break is the control.

ReleaseTwicestabbed lady beetleNothing to release — conserve the native twicestabbed lady beetle
SPRING, ON YOUNG FRUIT

Tarnished plant bug

One of the catfacing insects: its feeding on young fruit leaves dimples and crevices. It breeds in weeds, so keep them down under and around the trees.

ReleaseBig-eyed bugsWild — not sold; conserve the ones already present
LATE SUMMER

Brown marmorated stink bug

Feeds all season, leaving catfaced or pitted fruit; on peaches the damage may only show when the fruit is cut open.

ReleaseSamurai waspWild — conserve; not for release
SPRING

Green peach aphid

In cold climates its eggs overwinter on peach, apricot and plum; colonies build there in spring, and heavy ones curl the leaves, before winged aphids move on to vegetables.

ReleaseHoverfliesWild — attract adults with open flowers
EARLY SPRING

Eastern tent caterpillar

Silk tents in the forks of wild cherry, plum and peach. Cut out egg collars in winter and pull out small tents in spring.

ReleaseBt (kurstaki)Label rate — confirm stone fruit is on your product's label
LATE MAY TO JUNE

Rose chafer

Tan, long-legged beetles that skeletonise leaves and damage cherries and peaches for three to four weeks. Hand-pick or cover the trees.

ReleaseNo beneficial — hand-pick or coverNothing to release
SUMMER, AT NIGHT

Earwigs

Gouges and holes in ripening apricots and other soft fruit. Band the trunk with a sticky barrier and pick the fruit as soon as it ripens.

ReleaseNo beneficial — trap themNothing to release — none is sold
LATE SPRING TO EARLY FALL · TWO GENERATIONS

Pearslug (cherry slug)

Slimy, olive-green to black sawfly larvae graze the top of cherry and plum leaves down to the veins, and the second generation is usually the bigger one. Wash them off with a hose, which spares their natural enemies (UC IPM). Bt does not work on sawflies.

ReleaseWild parasites and predators, which UC IPM says often keep it in checkNothing to release

Season calendar

US · QUALITATIVE READING · VARIES WITH BLOOM DATE
JFMAMJJASOND
Plum curculioJan: QuietFeb: QuietMar: QuietApr: QuietMay: Pest pressure highJun: Pest pressure highJul: BuildingAug: QuietSep: QuietOct: QuietNov: QuietDec: Quiet
Oriental fruit mothJan: QuietFeb: QuietMar: QuietApr: BuildingMay: BuildingJun: Pest pressure highJul: Pest pressure highAug: Pest pressure highSep: Pest pressure highOct: QuietNov: QuietDec: Quiet
Peachtree borerJan: QuietFeb: QuietMar: QuietApr: BuildingMay: BuildingJun: Pest pressure highJul: Pest pressure highAug: Pest pressure highSep: Pest pressure highOct: BuildingNov: QuietDec: Quiet
San Jose scaleJan: QuietFeb: QuietMar: QuietApr: BuildingMay: Pest pressure highJun: Pest pressure highJul: Pest pressure highAug: Pest pressure highSep: Pest pressure highOct: BuildingNov: QuietDec: Quiet
Stink bugJan: QuietFeb: QuietMar: QuietApr: QuietMay: QuietJun: QuietJul: BuildingAug: Pest pressure highSep: Pest pressure highOct: Pest pressure highNov: QuietDec: Quiet
Tent caterpillarJan: QuietFeb: QuietMar: BuildingApr: Pest pressure highMay: BuildingJun: QuietJul: QuietAug: QuietSep: QuietOct: QuietNov: QuietDec: Quiet

Starter program

A home-orchard plan for stone fruit is mostly about timing. The one release in it is nematodes at the base of the trunk; the virus and Bt are sprayed like any other product.

  1. DORMANT SEASONHorticultural oilWet the trunk, limbs and branches against overwintering San Jose scale, before bud break, at the label rate for stone fruit (2.5–7.5 tbsp per gallon on the Bonide label), between 40 °F and 90 °F. Keep people and pets away until the spray has dried, and keep it out of ponds and streams (toxic to fish)
  2. EARLY SPRINGBt (kurstaki)On small tent caterpillars as the new tents appear, where the label lists stone fruit
  3. SPRINGCheck for wilted shootsLook over the trees in early spring for wilted oriental fruit moth shoot tips; Kentucky says they show that later generations may attack the fruit
  4. FIRST EGG HATCHCodling moth granulovirus (Madex HP)Labelled for oriental fruit moth on peach, nectarine, apricot, plum and cherry: ½ tsp per 5 gal of water, at least twice per generation
  5. PETAL FALL ONPick up dropped fruitDestroy drops promptly in late spring and early summer, before the plum curculio grubs leave them for the soil
  6. SPRING OR LATE SUMMER TO AUTUMNNematodes at the trunk base300,000 to 1 million per tree on moist, warm soil, against peachtree borer larvae already in the tree (spring) or as prevention (late summer to autumn)

Setting up the garden

Most of what protects a backyard stone-fruit tree is sanitation and restraint.

Keep broad-spectrum sprays out of the tree

UC IPM records 80–90 % parasitism of oriental fruit moth by August and September in orchards where broad-spectrum insecticides are not used, and warns that high label rates of the pyrethroid esfenvalerate can set off secondary pest outbreaks. Broad-spectrum sprays also kill the lady beetles and wasps on San Jose scale.

Clear the drops and the dead wood

Clemson's first step against plum curculio is removing and destroying dead, diseased and damaged wood and fruit. Plum curculio grubs leave dropped fruit to pupate in the soil.

Keep the trunk base clear

Pull mulch, weeds and grass back from the trunk, remove suckers and avoid wounding the bark, which is where peachtree borers get in.

Keep the weeds down

Tarnished plant bugs breed in the weeds around a planting, and Clemson's advice against the catfacing bugs starts with removing weeds and debris.