   The Chinese Jujube - December 3, 2003 Jeff Schalau, County Director, Agent, Agriculture & Natural Resources Arizona Cooperative Extension, Yavapai County Several years ago while walking across the University of Arizona campus, I saw a unique tree that did not recognize. The tree was about 25 feet tall, had shiny foliage, flaky, light gray bark, an upright trunk with pendulous branches, and was covered with small shiny fruits. Luckily, the tree had a small sign next to it: Chinese Jujube (Ziziphus jujuba). I wondered if this tree could be grown in northern Arizona. The answer is yes - that is, if you can find one. The Chinese jujube (also known as the Chinese date) is a member of the Buckthorn family (Rhamnaceae) and has been cultivated fro over 4,000 years in China. Over 400 cultivars have been selected. Seedlings were introduced to the U.S. in 1837 but cultivars were not introduced until 1908. Eighty three varieties were introduced by 1914. They were never widely planted in orchards but mature specimens can be found in collections and in residential landscapes here and there. Chinese jujubes are deciduous and can tolerate cold winters to -28 degrees F. The have a low chilling requirement allowing them to produce fruit in areas having mild winters. Long, hot summers are necessary to ripen good fruit crops. Flowers are small, approximately, 1/5 inch diameter, white, somewhat fragrant, and produced in large numbers in leaf axils. Flowering period extends over several months from late spring into summer. Most jujube cultivars produce some fruit without cross pollination, but reports from California indicate that yields are much higher when two or more different cultivars are planted together. Pollination is done by bees and flies. The fruit varies from round to elongate and from cherry-size to plum-size depending on cultivar. It has a thin, edible skin surrounding whitish sweet flesh. The single hard stone contains two seeds. The immature fruit is green in color, but mahogany-colored spots appear on the skin as the fruit ripens, and the fully mature fruit is entirely brown. Shortly after becoming fully brown, the crisp fruit begins to soften and wrinkle. The fruit can be eaten after it becomes wrinkled, but most people prefer them during the 3-5 day interval between the first appearance of the brown color and the time when wrinkling begins. The crop ripens non-simultaneously, and fruit can be picked for several weeks from a single tree. Jujubes tolerate many types of soils, but prefer sandy, well-drained soils. They are also able to grow in soils with high salinity or high alkalinity. Although the Chinese jujube will tolerate drought, regular irrigation is necessary to assure a quality fruit crop. Fertilizer requirements have not been studied, but jujubes appear to do well with little or no fertilization. The Chinese jujube appears to have no serious disease, insect, or nematode pests in the U.S. The University of California at Davis has indicated that they are susceptible to decay causing fungi if physically damaged. As mentioned previously, Chinese jujube trees are not widely available. Seedlings will have varying fruit qualities and should be grafted for fruit production. Varieties “Li” and “Lang” may be the most readily available, but interest is increasing and more varieties should become commercially available. Unfortunately, I am not aware of any local growers or nurseries that stock Chinese jujubes. I did find several references on the Internet, but this would require out of state shipping and could involve quarantine issues. If any readers are aware of a local or in-state source of Chinese jujubes, please let me know. 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 mgardener@verdeonline.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://ag.arizona.edu/yavapai/anr/hort/byg/. |