Notes on Nut Insects
Big bud mite of hazelnut
Identification
Adults of big bud mite (Phytoptus avellanae or Cecidophyopsis vermiformis)
are extremely small, white, cigar-shaped mites.
Period of activity
In spring, female mites leave the buds where they overwinter, to invade
the young leaves and lay eggs. After egg hatch, the nymphs develop on
the leaf surface and change into adults by summer. In late summer and
early fall, adults move inside new buds of the current year's growth.
The adults breed in fall and overwinter inside buds. Feeding occurs inside
the buds in fall and spring. It causes female flower buds to enlarge and
swell larger than normal. Female flower buds suffer more damage than vegetative
buds or male catkin buds. In late spring, damaged buds die and dry up
but remain fixed to the stem.
Monitoring
Monitor for damaged buds, which are easy to spot. Monitoring for adult
activity can be difficult due to the small size of this mite. In mid-May,
place Tanglefoot on twigs that surround damaged, swollen buds. Check for
extremely small adult mites using a 20× hand lens on the surface
of bark near the buds as they emerge for summer.
Management notes
Currently there are no chemical controls registered to manage big bud
mite infestations on hazelnuts. New hazelnut cultivars are being screened
for tolerance to big bud mite.
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