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Cranking up the cranberry, can cranberries defend themselves?

Cranking Up the Cranberry

Can Cranberries Defend Themselves?

It sits there on the Thanksgiving plate--a quivering, ruby-red jelled mold or a juicy, berried sauce. Just a couple of spoonfuls may be enough.

Cranberries are as traditional as the golden brown turkey or the kids dressed up like pilgrims for the Thanksgiving play.

No one seems to be able to determine whether or not the pilgrims served the little red berries at that first Thanksgiving dinner in 1621, but for sure the cranberry has since become part of the American heritage.

And ARS is helping to keep the tradition alive. In a joint research venture with Rutgers University's Blueberry and Cranberry Research Center, Allan W. Stretch is trying to find ways to help cranberry growers.

Stretch, a plant pathologist, heads the ARS part of the cooperative cranberry research effort with Rutgers at Chatsworth, New Jersey.

"Since Rutgers University breeds for new varieties here at Chatsworth, ARS concentrates its research effort on controlling diseases," Stretch says.

"Fruit-rotting fungi are cranberries' most serious disease problem," he says.

One of the fruit-rot problems targeted for research is black rot caused by the fungus Allantophomopsis lycopodina. Black rot can also be caused by two other fungi, A. cytisporea and Strasseria geniculata.

"Black rot infects fruit and spreads during water harvest, which is about 2 months after the last application of fungicide," Stretch explains. "This leaves the cranberries unprotected."

He is seeking alternatives--specifically, naturally occurring biocontrol agents.

"We've looked at the success others have had with natural bacterial, yeast, and fungal antagonists to control disease organisms on other fruit. We know there are similar biocontrol agents present in cranberries," Stretch says.

And he has started work to find them. As in the case of stone fruit, Stretch hopes to find an agent that may trigger a defense reaction in the cranberry to fight the rot or one that might produce an antibiotic effective against fungal growth.

Cranberries are one of the specialty crops that will be affected if certain "minor-use pesticides" are lost to growers because manufacturers choose not to retain registration.

This situation stems from a 1988 law giving the Environmental Protection Agency authority to reassess the safety of thousands of chemicals already in use. These chemicals need to be registered, and manufacturers must bear part of the registration fees and pay for studies to ascertain safety. This could prove too costly for the minor-use pesticides.

These are pesticides that are applied on small acreage crops--any crop other than wheat, corn, soybeans, sorghum, or cotton. Prospective loss of these pesticides makes Allan Stretch's research even more important to cranberry growers.

Potential loss of certain pesticides greatly concerns Nicholi Vorsa, too. Vorsa, a plant breeder/geneticist at Rutgers University, is trying to broaden the genetic base for cranberries in hopes of developing disease-resistant varieties.

"Six of the seven cranberry varities released since the late 1800's were developed under USDA leadership. However, our genetic base is still too narrow," he says.

The industry is still largely based on selections from the wild. "ARS' search for biocontrol is one approach, but we also need a disease-resistant variety. Ideally, we'll couple that resistance with reliable productivity."

But crop breeding takes time. From cranberry seed to flower takes about 2 to 3 years. And selecting for yield can take up to 10 years or more.

Cranberries, says Vorsa, are a wetlands species. Because of legal restrictions on wetlands, it's difficult for cranberry growers to expand their acreage. One way to meet increased demand--now that the red berries are no longer just a seasonal crop--is to plant more productive varieties.

"There's also an ever-growing market for cranberry juice," says Jack Crooks. Crooks, manager for agricultural research at Ocean Spray, says that about 90 percent of the cranberry crop goes for processing.

"We're supportive of the ARS and Rutgers University research. In fact, we'd really like to see ARS also involved in breeding."

Because cranberries are a specialty crop, there are only a few people doing genetics research. Vorsa, one of the few cranberry breeder/geneticist in the country, agrees that there is plenty of room for others to share in this work. "Since cranberries are grown in states having varied climates and problems, there is a need for additional breeding efforts."

"A new variety needs grower confidence," Crook says. "That can only be gained through proven research, field tests, and having the proven varieties available to growers."

Headquartered in Lakeville-Middelboro, Massachusetts, Ocean Spray is a cooperative of grower-owners from five states and two Canadian provinces that produce cranberries, plus Florida grapefruit growers.

The cranberry, which got its name from its droopy blossom that looks like the head and beak of a crane, and the blueberry and Concord grape make up the three economically important fruits native to North America.

From 27,700 acres of cranberries grown in 1990, growers harvested about 169,000 tons of fruit, valued at over $147 million. Massachusetts is the largest producer, followed by Wisconsin.

"Cranberries are remarkable because they grow in areas considered wastelands for other agricultural crops," Stretch says. "Unlike rich topsoil, a cranberry bog never wears out."

Most other agriculturally important plants can't exist in the acid soil of marshy bogs that are ideal for cranberry culture.

Planting a new crop of cranberries--perennial plants that produce an annual crop--is unlike planting any other crop. Growers simply cut the vines and spread them, a ton per acre, on land that has been leveled and covered with about 3 inches of coarse sand. Vines can then be hand-planted or disked into the sand where roots and top growth develop within about 2 weeks. The plant spreads by runners and then in the second year produces uprights--shoots that grow up from the runners. Fruitbearing vines completely cover the ground by year 3.

Water is essential for a good cranberry crop. Cranberries need more water than any other agricultural crop.

In northern temperate regions, growers flood their crop in winter; an ice blanket keeps the vines from drying out and maintains a steadier temperature for the dormant crop. The flood, which also protects against frost, is removed in spring but is reapplied to a depth of about 4 to 8 inches for harvest around October.

A harvesting machine that looks like an eggbeater dislodges the fruit from their stems. As the berries float on top of the water, a simple wooden boom pushes them to a loading area where conveyor belts carry them into waiting trucks. Within 24 hours, the fruit is cleaned and on its way to freezer storage.

Some growers dry-harvest with a piece of equipment that has what looks like a giant steel comb attached. The vines pass through the teeth which snaps the berries off. The berries are then transferred to burlap sacks for removal from the field.

Dry-harvested cranberries store better than wet-harvested ones. Refrigeration will keep berries for several months. In a fairly cool autumn, berries keep in common storage about 2 or 3 months. Not much storage time is needed for a crop that is processed in so many ways: sauce; juice cocktail; blended with apple, raspberry, blueberry, grape, and apricot juice; cranberry-orange relish; candied and spiced cranberries; and liqueurs.

PHOTO : ARS plant pathologist Allan Stretch (left) and associate professor Nicholi Vorsa of Rutgers' Blueberry and Cranberry Research Center examine the fruit resulting from crosses of Pilgrim and McFarlin cranberries. (K-4421-1)

PHOTO : Cranberry half at right has black rot caused by a fungus. (K-4420-11)

PHOTO : Damaged cranberries are dipped in a bacterial solution to see if it will inhibit fungi that cause black rot. (K-4420-2)

Allan W. Stretch can be reached at USDA-ARS, Blueverry and Cranberry Research Center, Rutgers University, Penn State Forest Rd., Chatsworth, NJ 08019. Phone (609) 726-1950.
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Title Annotation:includes related article on cranberry bog
Author:Stanley, Doris
Publication:Agricultural Research
Date:Jan 1, 1992
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