What's eating my english walnut 'tulare'?

English walnut 'Tulare' shares all the key pest pressures of Juglans regia. Codling moth and walnut husk fly are the two most damaging nut pests. Walnut aphids cause honeydew and sooty mould. Squirrels harvest nuts before maturity. UC IPM identifies these as the major pests requiring management in all commercial and garden walnut plantings.

Maggots tunnel through the husk, causing black, decayed tissue and severely stained shells; kernels may be shrunken and discoloured. Yellow sticky traps with ammonium acetate lure monitor adult emergence (July–August). Permitted insecticides (spinosad) applied at first adult catch and repeated every 7–10 days protect the crop.

Larvae tunnel directly into the nut and consume the kernel; infested nuts drop early with a sawdust-like frass entry hole. Use pheromone traps to monitor flight; time insecticide sprays (codling moth granulosis virus or spinosad) to egg hatch. Mating disruption dispensers are effective for whole-orchard use.

Yellow aphid colonies on leaf undersides; heavy infestations produce copious honeydew, ants, and black sooty mould reducing photosynthesis. Encourage natural enemies (parasitoid wasps, syrphid flies). Insecticidal soap or a strong water jet controls flare-ups. Avoid broad-spectrum insecticides that destroy beneficial insects.

Remove and cache nuts weeks before maturity, stripping the entire crop on small trees. Tree-trunk guards prevent climbing. Harvest promptly as husks begin to split. Netting small trees is practical.