Chestnuts have been enjoyed for centuries. Asian chestnuts (Castanea crenata or C. mollissima) are mentioned in poetry as far back as 5,000 years ago and early Europeans arriving in the New World found forests of American chestnuts (Castanea sp.) blanketed the East Coast from Georgia to Maine and as far west as the Mississippi River. But while the Asian cultivars are still going strong, the American chestnut was all but wiped out in the early 1900s in one of the West’s worst botanical disasters. An attempt to import Chinese chestnut trees brought in chestnut blight (Cryphonectria parasitica), to which Asian chestnut trees were mostly immune but American trees were not.
Fifty years and up to 5 billion dead trees later, the American chestnut began a slow process of recovery that continues to this day. Producing less than 1 percent of the world’s chestnut supply, most chestnuts consumed in the United States come from Italy. New varieties, developed at the end of the twentieth century, include a wheat gene resistant to chestnut blight that produces a tree almost identical to the wild American chestnut.
With seeds that look similar to buckeyes, chestnuts belong to the Fagaceae or Beech family. Often roasted, the seed shell must be pierced to prevent it from exploding due to the high moisture content. Chestnuts can also be eaten raw or even ground into flour for baking. Larger nuts are considered preferable for fresh market sale. Depending on cultivar, chestnuts range from the sweetest American varieties to some less sweet European and Chinese nuts. The skin around the seed kernel is bitter and needs to be removed for eating. American and Chinese chestnuts are generally the smoothest and easiest to peel, making them popular for commercial marketing.
References: Agricultural Marketing Resource Center, UC Davis Fruit/Nut Research & Information Center, University of Florida/IFAS Extension, University of Illinois Extension, USDA, Western Growers Association.
TYPES, VARIETIES & CUTS
There are four major species of chestnut tree. The American chestnut (Castanea dentate) has an upright tree form and produces smaller, sweeter nuts. The European chestnut (C. sativa) is native to Western Asia, Europe, and North America. European trees also have an upright form, but tend to produce bitter or bland nuts that are larger though harder to peel. Both American and European trees are susceptible to blight.
Chinese chestnuts (C. mollissima) are native to Northern and Western China and tend to have a low, spreading form with many branches at ground level though some Chinese cultivars have an upright form. These very blight-resistant trees yield medium-sized, sweeter, easy to peel nuts. Japanese chestnuts (C. crenata) are native to Japan and China, are also blight-resistant, and tend to be smaller with a spreading form. Nuts from Japanese trees are large but have an undesirable taste so the trees are used primarily for hybridization. Trees in the Castanea family are very similar and hybridize easily, often making species difficult to distinguish.
Chestnuts are primarily sold fresh in the shell and the USDA classifies them by size as Large, Giant, Jumbo, or Mammoth.
References: Chestnut Growers of America, UC Davis Fruit/Nut Research & Information Center, University of Florida/IFAS Extension, University of Missouri.
PESTS & DISEASE
Chestnut trees are susceptible to a few pests such as the chestnut weevil, oriental chestnut gall wasp, spider mites, shot hole borers, filbert worms, and even deer and squirrels.
Chestnut trees are also susceptible to certain diseases. Cryphonectria parasitica or chestnut blight is the most notable for the damage done to American chestnut trees. Other diseases include alternaria spp, aspergillus niger, botrytis cinerea, fusarium spp, penicillium spp, phomopsis castanea, phytophthora root rot (also known as ink disease), leaf spot, powdery mildew, and armillaria mellea (also known as oak root fungus). Asian chestnuts are particularly susceptible to twig canker.
References: Cornell University, UC Davis Fruit/Nut Research & Information Center, UC Davis Postharvest Technology Center, University of Florida/IFAS Extension.