Strategies for Limiting the Spread of Asian Chestnut Gall Wasp in North America

Asian gall wasp (Dryocosumus kuriphilus Yasumatsu) is a major pest of chestnut trees in China, Japan, and Korea and was introduced into Georgia in 1974. Species affected by the gall wasp include Castanea dentata (American chestnut), C. mollissima (Chinese chestnut), C. crenata (Japanese chestnut), C. sativa (European chestnut), and C. pumila (chinquapin). Since the gall wasp was introduced into North America, it has become established in eleven states in the eastern United States. Gall wasps are distributed by the transport of infested chestnut seedlings to new areas and by the exchange of infested scion wood used to graft new trees.  Gall formation on trees adversely affects foliar and terminal shoot growth and chestnut production. Some of the strategies for limiting further infestations of this pest have been the implementation of plant quarantines by some states, planting resistant chestnut cultivars, and using sources of clean scion wood from gall wasp-free sites. Hot water submersion and heat treatments using a magnetic field have been tested as methods to eliminate overwintering larvae in dormant scion buds. Both techniques have limitations and grafted trees must remain in quarantine to determine the efficacy of disinfestation treatments because larvae are not easily detectable before bud break.