   Chestnuts - January 30, 2008 Jeff Schalau, Associate Agent, Agriculture & Natural Resources University of Arizona Cooperative Extension, Yavapai County The eastern United States once had extensive native forests of American chestnut (Castanea dentata). European chestnuts (C. sativa) were introduced in the early 1700s, Japanese chestnuts (C. crenata) in 1860, and Chinese chestnuts (C. mollissima) in the late 1800s. Unfortunately, chestnut blight, a canker causing fungal disease, was accidentally introduced to the U.S. in 1906. This destroyed almost all the American and most of Japanese and European chestnut trees here. Chinese chestnuts are highly resistant to chestnut blight. Chestnut trees are in the same family as beeches and oak (Fagaceae). The nuts develop inside of a spiny burr. This burr is the equivalent of the cap on an acorn. The tree has gray bark and is deciduous, with leaves that are 5 to 7 inches long, sharply serrated, and oblong in shape. While breeding programs are in place, much of the world’s chestnut production comes from natural stands. Like walnuts and pecans, chestnuts have separate male and female flowers. Flowers appear from mid-June to mid-July so they are not subject to late spring frosts. The pollen has a distinct odor and attracts bees. However, bees are not attracted to the female flowers (they have no nectar) and pollination occurs primarily by wind. The fleshy nut has a starchy texture and low fat content which makes it comparable to a cereal grain. The nut contains about 40% carbohydrate, 40% water, 5 to 10% protein, and less than 5% fat. Chestnuts are receiving recognition as a healthy food, unlike other nuts, which contain well over 50% fat. Chestnuts also contain a high-quality protein. Chestnuts are a traditional food in Europe and Asia where they are consumed fresh, cooked, candied, and as a source of flour for pastries. Chestnut flour is also substituted for wheat flour by people with grain allergies. The chestnut is probably the most important nut crop in the temperate zone (the areas between the tropics and polar circles), ranking behind the coconut and peanut in importance. Since it is indigenous to all three continents of the northern hemisphere, the chestnut has a long history of cultivation. The Japanese chestnut has been cultivated for 1,000 years and the Chinese chestnut for 6,000 years. The ancient Greeks are thought to have first cultivated the European chestnut bring it from Asia Minor, via Turkey, to southern Europe and North Africa. Chestnuts clearly have had a profound influence on past and current civilizations. Their nuts served as a year-round food source for people and animals. The American chestnut was a premier tree providing rot-resistant wood for houses, barns, railroad ties, fences, and fuel. It also provided tannin for leather processing and of course, the nuts as food for humans and wildlife. While some American chestnuts remain in the wild, most have succumbed to chestnut blight. Most of the remaining mature individuals are geographically isolated from areas where major populations once were. Researchers are looking into increased resistance by crossbreeding chestnut species and cultivars and to possibly alter the virulence of the disease itself. Across the country, small acreages are being planted with chestnuts for commercial production. Most growers have planted the blight-tolerant Chinese species or its hybrids. California growers are beginning to plant them there. The most commonly planted variety is called ‘Colossal’: a hybrid of European lineage. For successful pollination, you must plant more than one named variety or a named variety and a seedling. I am not aware of any chestnut trees planted in Yavapai County, but I’m sure they have the potential to grow and produce here. They are available from many mail order and on-line nurseries. For more information about chestnut varieties and culture, visit the Northern Nut Growers Association web site at: www.icserv.com/nnga/faqchest.htm. Speaking of nuts, don’t forget about Camp Verde Pecan, Wine, and Antique Festival in downtown Camp Verde on February 8, 9, and 10. Hope to see you there! The University of Arizona Cooperative Extension has publications and information on gardening and pest control. If you have other gardening questions, call the Master Gardener line in the Cottonwood office at 646-9113 ext. 14 or E-mail us at cottonwoodmg@yahoo.com and be sure to include your address and phone number. Find past Backyard Gardener columns or submit column ideas at the Backyard Gardener web site: http://cals.arizona.edu/yavapai/anr/hort/byg/. |