Cherries

Background

Cherries may be either deliciously sweet and deep brown-red, or quite tart and bright red. The two most common are the sweet cherry, Prunus avium L., and the sour (often referred to by growers as the pie or tart) cherry Prunus cerasus L.. Sour cherries have a lower sugar content and a higher acid content than its sweet counterpart. Not surprisingly, sour cherries are slightly less caloric than sweet cherries, containing about 60 calories per 3.5 oz (100 g) portion compared to 80 calories for sweet. Cherries are high in vitamin C, carbohydrates, and water, and include trace amounts of fiber, protein, vitamin A, vitamin B1 (thiamin), vitamin B2 (riboflavin), niacin, calcium, phosphorus, iron, and potassium.

Cherries are found in the wild and have been domesticated for centuries. There is a myriad of cherry types, resulting from new varieties and hybrids developed for hardiness and flavor. This fruit is found in Asia, Europe, and North America, with Iran, Turkey, United States, Germany, and Italy leading in the production of cherries. Together, 10 countries produce over 1.1 million short tons (over one million metric tons) of cherries annually.

Cherry trees offer products other than the fruit itself. The lovely, fragrant cherry blossoms are a rite of spring and are actually a tourist draw in places such as Washington, DC, and Door County, Wisconsin. In addition, parts of the tree itself have long been used for medicinal purposes. The bark, leaves, and seeds of the cherry trees contain cyanogenic glycosides—poisons that are lethal if ingested by children or animals. Native Americans and others use the leaves and carefully prepare teas with them for the treatment of colds or coughs. Others have experimented with cherry stalk tea in the treatment of kidney diseases. The cherry has also been associated with virginity from ancient times to the present day. The association may be derived from the fact that the red colored fruit that encircles a small seed symbolizes the uterus of Maya, the virgin mother of Buddha, who was offered fruit and succor by a holy cherry tree while she was pregnant.

History

The sweet cherry originated in the area between the Black and Caspian Seas in Asia Minor. It is likely that bird feces carried it to Europe prior to human civilization. Greeks probably cultivated the fruit first. Romans cultivated the fruit as it was essential to the diet of the Roman Legionnaires (their use likely spread the fruit throughout Western Europe). It is believed that English Colonists brought the fruit to the New World prior to 1630, but they do not seem to have flourished in the eastern United States. Spanish Missionaries brought sweet cherries to California, and varieties were brought west by pioneers and fur traders as well. Sour cherries also are native to Asia Minor, and were brought over to the New World by settlers rather early as well.

Today, the United States probably produces more tart cherries than sweet because the former are easier to grow. They are simply less fussy and are affected less by bad weather. Thus, they flourish in greater numbers. Now, cherry growers are able to purchase a variety of cherry types that best suit the soil and climate in which they operate.

Cherries are mechanically harvested using a tree shaker that knocks the fruit from the tree. Once picked, cherries are quickly processed and sent to market or to be frozen, canned, or used in other products.

Raw Materials

Generally, cherries flourish in deep, well-drained, loamy soils. Cherries require cooler climes rather than hot ones because they must be chilled for about 1,000 hours annually. The cherry trees bloom relatively late in spring, so frost is less of a hazard for this stone fruit than others such as peaches or apricots. However, too much frost late in the spring may adversely affect cherry production. The clime must be one that does not have excessive rain during harvest since too much rain at that time can cause the fruit (particularly sweet cherries) to crack. Tart cherries are a bit easier to cultivate and are more tolerant of frost as well as humid, rainy weather. The relative ease with which tart cherries are grown may be one reason why so many are grown in the United States.

Trees of good stock are also necessary for successful cultivation of cherries. It is imperative to acquire stock through tree nurseries that are suited for the soil and climate of the grower's region. Bees, however, ensure that the cherry trees flower and ultimately produce fruit, and are an extremely important ingredient in the cultivation of cherries. Bees are usually brought into the tree orchard in the spring as the flowers first bloom in order to distribute pollen so that the fruit blossoms. Bee hives are generally rented by cherry growers each year. It remains imperative that fertilizers are applied to domesticated cherry trees via foliar (leaf-applied) feedings. Pesticides and fungicides are applied before harvest to deter diseases and pests.

The Production Process

Soil preparation

Different varieties of cherry trees flourish in slightly different soils. Generally, cherries prefer a moderate pH of 6 or 7. Most orchard owners periodically test the soil to ensure the pH is near that mark and may add special fertilizers to treat the soil. Extensive use of fertilizers may encourage vigorous growth but may retard blooming and fruit bearing, so cultivators must carefully assess their use of fertilizers.

• 1 Root stocks are carefully chosen by cherry growers for their lineage and compatibility with the soil and climate of the orchard. Lineage, as one grower puts it, means that the stock is from healthy, dependable trees from reputable fruit nurseries. There is much contention about the most dependable root stocks for both sweet and tart cherries. A new root stock from Germany (a significant source for cherries) named Gisela allows production from dwarf trees with high yield efficiency and fairly early production.
• 2 Some varieties of cherry trees, particularly those of the Pacific Northwest, do not naturally produce many branches. Thus, the center of the tree may be dense with a central limb. It is therefore essential for growers to prune the trees regularly so that all the flowers (and ultimately, fruits) receive the amount of sunlight and air circulation required for fruit production. This pruning may be done prior to harvest, after harvest, or at both times. Some growers are experimenting with ways to encourage branching (which still may require pruning). These trees must be carefully maintained. It takes five or six years for sweet cherry trees to produce fruit, with maximum yields obtained at about that time. Sweet cherry trees produce fruit for up to 30 years. Tart cherry trees produce fruit after about three years, and produce fruit for 20 to 25 years.

Fungicides and insecticides

The schedule for applying fungicides and insecticides may vary from orchard to orchard. Some growers apply the first fungicides at floral bloom in spring to prevents leaf spot. Insecticides to keep off bore worms and/or other insecticides may be applied every two weeks or so until harvest.

• 3 Bees must pollinate the flowers. Just as the trees begin to blossom, cherry growers let bees loose in order to distribute the pollen so that fruit will blossom. The flower must be pollinated in order for the tree to bear fruit. Bees may be set in alternate rows to ensure pollination. Generally, 25-50% of flowers must set fruit each year in order for the crop to be commercially viable.
• 4 It is approximately two months from flower to fruit. As the fruit ripens, growers hope for no frost and just the right amount of rain—too much rain will crack and damage the sweet cherries. Maturity is gauged by a variety of means, and may vary by grower. Traditionally, color has been a key indicator. Growers are increasingly moving toward determining fruit removal force—the easier it is to remove the fruit, the more mature it is. This maturity is measured by a pull gauge that pulls the fruit from its pedicel. Just before harvest, some growers who use tree-shakers to shake the cherries off their stems apply a spray that makes it easier for the cherries to drop off the tree.
• 5 Both sweet and tart cherries intended for processing are shaken from trees when ripe. Tree trunks are shaken by a machine that forces the cherries from the tree; it takes just five seconds to drop the fruit from the tree using a shaker. The fruit drops onto a cloth or plastic cover so that it can be easily gathered. (Tree shaking is an ordeal for the grower as well as the tree—the machines are very expensive and if the shaking is done incorrectly, the machine vibrations may damage trees, particularly young trees.) However, sweet cherries that are to be consumed fresh are laboriously hand-picked and carefully boxed for prompt sale.
• 6 Cherries are now ready to be processed into consumer or retail produce items. Cherries that are to be processed (canned, dried, or frozen) are quite delicate and are easily bruised. They also have a short shelf life, so they must be processed immediately. Tart cherries shaken from trees are immediately plunged into cold water and conveyed to processing plants, where they are washed, de-stemmed, pitted, and packed for freezing within hours of harvesting. Sweet cherries picked for fresh consumption may be hydro-cooled or dumped into cold water by pickers, then packed in shallow flats after being sorted based upon their size and color. Sweet cherries are then immediately shipped out, since their shelf life is just two weeks. They are still prone to brown rot and a variety of molds during this time.
• 7 For many growers, there is little preparation of the trees for the winter. After harvesting, another spray is applied to foliage to prevent harmful leaf spot. Pruning of limbs and branches often happens after harvesting as well. Other than that, the trees are left unprotected. Cherry trees, like most trees, prefer a fall that gradually gets colder rather than one that is very warm and then very cold suddenly. The gradual cooling of the tree is called "hardening off" so that the tree is eased into the cold weather.

Quality Control

Cultivating a commercially viable cherry crop has many components. First, the soil pH and nutrients must be tested frequently (generally by a state university extension service) so that foliar fertilizers meet the requirements of the trees. Generally, growers keep a record of these soil tests. Second, the grower must understand the climate and soil types well enough to choose root stock that will flourish in that area. Third, pesticides or insecticides must be very carefully mixed and applied according to U.S. Environmental Protection Agency (EPA) standards, recommendations of state university extension services, and the product label. Fourth, pollination of the cherry blossoms is absolutely imperative; if there are few bees in the area, growers must rent bees for this purpose. Fifth, the trees must be carefully shaken during harvesting (if the cherries are to be harvested) so that the tree is not irreparably damaged. Finally, vigilant pruning and assessing the amount of air and sunlight densely packed trees receive is imperative for large yields.

The Future

Perhaps the biggest issue looming for the cherry industry, which is fiercely independent and highly competitive, will be federal regulation of the crop (as other crop-growers are weaning themselves from these regulations). Tart cherry crops have been particularly problematic in the last several years. A bumper crop of tart cherries has resulted in exceedingly low crop prices (tart cherries are less affected by the vagaries of weather than sweet cherries and can be harvested in huge quantities). Several years ago the market was so saturated with tart cherries in Michigan that some growers were receiving five cents a pound for the crop, far below the twenty-cents per pound needed to break even. Federal regulations could establish the amount of cherries that may be offered for sale at market. Excess cherries may be frozen or stored, or given to charity. Some growers are trying to find ways to utilize these tart cherries in ingenious ways. A Michigan cherry grower recently combined lean ground meat with tart cherry pulp, resulting in a lean and tasty meat that appealed to the health-conscious. Others have turned to gourmet foods such as dried cherries, yogurt-covered cherries, or have developed specialty cereals in order to utilize the abundance of tart cherries.

Other issues involve the land upon which the cherries are grown. The cultivation of cherries is very labor-intensive and subject to the weather. Equipment is expensive, too; a cherry shaker alone may cost $175,000. Younger generations increasingly are un-willing to manage the family cherry orchard, realizing that much hard work may not even pay off in profits. Even established cherry growers are wondering if the work is worth the prices and uncertainty. In addition, many of these orchards are located in lush, lovely areas, and taxes on the prime parcels of land are putting some of the growers out of business. Families are deciding that it is not worth running the business, and are selling orchards that will be plowed under to make way for new housing.