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Bulletin E3457
Asian Chestnut Gall Wasp: An invasive pest of concern for Michigan chestnut growers


February 2, 2022 - <> and <>

Chestnuts (Castanea spp.) are grown and consumed by people around the world. While many people in the United States enjoy freshly roasted chestnuts in the winter, chestnuts are also used in a variety of products, from gluten-free flour to beer, liquors, and candy. The United States imports the vast majority of its chestnuts, but domestic production is steadily expanding. Michigan is the largest commercial producer of chestnuts in North America.

Unfortunately, the Asian chestnut gall wasp (ACGW) (Dryokosmus kuriphilus Yasumatsu) was discovered in Michigan in 2015. This tiny insect, a native of China, is a major invasive pest of chestnut trees in Japan, Korea, much of Europe, and the United States. At high densities, the spherical galls caused by the ACGW (Figure 1) can reduce tree growth and nut production. This invasive pest will continue to spread and could become a serious problem for commercial chestnut producers across the state. In this bulletin, we provide information on the ACGW, including its biology and impact. We also provide management options for dealing with the pest.



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