Pest identification
What's eating my chinese chestnut?
Chestnut weevil (Curculio sayi / C. elephas)
Signs: Larvae consume the kernel, leaving a round exit hole and hollow, inedible nut; a single infested nut can harbour multiple larvae.
Control: Collect and destroy fallen nuts daily; hot-water treatment (50°C/122°F for 45 minutes) kills larvae before storage; cultivate soil under trees to expose pupae.
Oriental chestnut gall wasp (Dryocosmus kuriphilus)
Signs: Galls form on new buds, shoots, and leaves, reducing growth and eliminating nut production on affected branches; a serious quarantine pest now established in parts of North America and Europe.
Control: No effective chemical control; biological control using parasitic wasp Torymus sinensis is deployed in Europe and is under study in North America; notify your state/county extension service if suspected.
Squirrels
Signs: Burrs opened and nuts cached starting in September before full ripening; losses in un-netted gardens can be near-total.
Control: Harvest as soon as burrs begin to open; pick up all windfalls daily; trunk baffles where feasible.
Chestnut mite (Eotetranychus hicoriae and related species)
Signs: Fine stippling and bronzing on leaf upper surfaces in mid to late summer; heavy infestations cause early defoliation.
Control: Avoid broad-spectrum pesticides that kill predatory mites; apply horticultural oil or insecticidal soap when mite populations are building; ensure trees are well watered during drought.
Keep chinese chestnut pest-free
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Chinese Chestnut pests — FAQ
What is eating my chinese chestnut?
Chinese chestnut is the backbone of blight-resistant breeding and has natural resistance to Cryphonectria parasitica. Its main nut pests are the chestnut weevil and oriental chestnut gall wasp (an invasive threat in North America). Squirrels are extremely aggressive competitors. Chestnut mites can cause stippled foliage in summer. Good orchard hygiene protects nut quality.
How do I get rid of chestnut weevil (curculio sayi / c. elephas) on chinese chestnut?
Larvae consume the kernel, leaving a round exit hole and hollow, inedible nut; a single infested nut can harbour multiple larvae. Collect and destroy fallen nuts daily; hot-water treatment (50°C/122°F for 45 minutes) kills larvae before storage; cultivate soil under trees to expose pupae.
How do I get rid of oriental chestnut gall wasp (dryocosmus kuriphilus) on chinese chestnut?
Galls form on new buds, shoots, and leaves, reducing growth and eliminating nut production on affected branches; a serious quarantine pest now established in parts of North America and Europe. No effective chemical control; biological control using parasitic wasp Torymus sinensis is deployed in Europe and is under study in North America; notify your state/county extension service if suspected.
How do I get rid of squirrels on chinese chestnut?
Burrs opened and nuts cached starting in September before full ripening; losses in un-netted gardens can be near-total. Harvest as soon as burrs begin to open; pick up all windfalls daily; trunk baffles where feasible.
How do I get rid of chestnut mite (eotetranychus hicoriae and related species) on chinese chestnut?
Fine stippling and bronzing on leaf upper surfaces in mid to late summer; heavy infestations cause early defoliation. Avoid broad-spectrum pesticides that kill predatory mites; apply horticultural oil or insecticidal soap when mite populations are building; ensure trees are well watered during drought.