CHESTNUT PRODUCTION IN MICHIGAN

Abstract

Chestnut (Castanea spp.) trees representing various species were established in North American orchards prior to and after chestnut blight eliminated the endemic, co-dominant American chestnut tree (C. dentata) from the eastern United States. Complex mixtures of chestnut species can be found in orchards where growers harvest the nuts for market. Before 1997, the nuts were produced on seedling (non-grafted) trees with germplasm mixtures of American, Chinese (C. mollissima), European (C. sativa) and Japanese chestnut (C. crenata). Beginning in the late 1990s and continuing today, grafted trees, including the Japanese/European hybrid cultivar 'Colossal' from California, and others were planted in orchards throughout Michigan. Today, Michigan is one of the few states where both European trees and Asian trees are grown in the same orchards. This mixing of different chestnut species in the same orchards provides opportunities to compare and contrast the many different types of trees and their nuts growing under similar environmental conditions. Unique attributes have been noted for the trees. The cultivar 'Colossal' in Michigan is precocious, produces very large nuts and bears the greatest yield of any cultivar in Michigan. However, 'Colossal' is not very cold tolerant, is chestnut blight susceptible, commonly produces multiple embryos, and can be quick to mold. Chinese chestnut trees in Michigan orchards are primarily represented by non-grafted seedling trees. These Chinese seedlings produce variably sized, good flavored sweet nuts, are chestnut blight resistant, and generally are easy to peel. However, they take many years to become established, can produce variable sizes and qualities of nuts, over half the trees never produce nuts and, except when greater than 15-years-old or more, do not yield well when compared to 'Colossal'. Certain Chinese cultivars have shown good promise under Michigan environmental conditions but they are slow to produce and cold weather susceptible. These and other challenges of chestnut production in Michigan will be discussed.