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College of Food, Agricultural, and Environmental Sciences


Unusual Weather Yields Variable Berry Production

August 12, 2002

COLUMBUS, Ohio - An unseasonably warm winter may have contributed to what's turning out to be a record season for Ohio blackberry growers.

Ohio State University horticulturist Dick Funt said that berry growers are reporting exceptional yields of eastern thornless blackberries, the best production in as many as 40 years.

"If during the last several years producers were averaging 100 percent yields, then this year is well over 110 percent," said Funt. "There are more berries than leaf surface - berries breaking out on the lower parts of the stem the likes which we have never seen."

Ohio State researchers have been plotting weather data for over 15 years, which indicates that when average daily winter temperatures remain above zero degrees Fahrenheit between December 15 and January 15, the likelihood of high berry yields increases.

"Long-term records for thornless blackberry production indicate that early warm winter 2002 temperatures may have resulted in the tremendous yields growers are experiencing now," said Funt. Blackberry production extends through Labor Day.

While blackberry growers are seeing a bumper crop, other berry producers this year have not been so lucky. A freak hailstorm in parts of southern Ohio, followed by a spell of record low temperatures in May, damaged the strawberry crop, resulting in at least a 50 percent drop in yields compared to last year.

"The strawberry crop went through winter very nicely. We were seeing an excellent crop until May, then we had that freeze and hailstorm so close to harvest," said Funt. "That combined with the saturated soils from an overly wet spring just devastated a lot of the plantings."

The low temperatures, which broke a 100-year record, froze 80 percent of the strawberry blooms.

Summer red and black raspberries were also affected by the cool, wet spring and the freezing temperatures that followed. Funt said yields were down by as much as 25 percent.

"Yields were lower in some cultivars due to cold temperatures that damaged the plants after they came out of dormancy," he said. "Frozen black raspberry blossoms were observed for the very first time in over 50 years."

The summer raspberry season ended in mid-July. The season for fall red, black and yellow raspberries, which escaped frost damage, began the end of July and will continue until the beginning of October. "We are predicting a good-to-average fall raspberry crop," said Funt.

Berry growers not only had to deal with unusual winter and spring temperatures, but now must wisely manage their crop in the face of dry conditions that have been gripping much of Ohio since June.

"Growers should consider irrigation for all berry types, and particularly where raised beds are used," said Funt. "They should design a system that can irrigate the crop over a period of several weeks."

August is one of the most important months for plant development and fruit size for the following season.

"Lack of adequate water can reduce vigor of new growth for the following year. Some new plantings may stress so much in the face of inadequate moisture that they may not grow at all," said Funt. "A smaller leaf surface means poor flower development, resulting in poor fruit size."

Funt said a trickle irrigation system is important for raised bed systems, since the plants sit higher in the ground and may not have access to sufficient soil moisture. Also, applying compost to the plants helps retain soil moisture during times of dry weather.

Water management not only impacts a grower's investment, but may also play a part in the health of the person eating the berry, said Funt.

"Good, healthy soils lead to good, healthy plants, which lead to a healthy person," he said. Researchers speculate that berries pack the most nutrient punch when harvested from the plant and immediately consumed or preserved through freeze-dried techniques.

Freeze-dried raspberries are the center of Ohio State cancer researcher Gary Stoner's work. Stoner has demonstrated that a 5 percent to 10 percent concentration of freeze-dried raspberries mixed in the diet can cut esophageal cancer in rats 40 percent to 60 percent and colon cancer by 80 percent. Stoner plans to conduct the same tests in humans later this year.

Preliminary toxicity tests have shown that the berries are not toxic to humans when consumed in large quantities, prompting Stoner to proceed with his clinical trials. "Two bowls of raspberries, equal to 90 grams, eaten every day for 14 days, were tolerated very well," said Stoner, a researcher with the Arthur G. James Cancer Hospital and Richard J. Solove Research Institute in Columbus, Ohio.

Stoner plans to study the effects of human berry consumption on three types of conditions that can lead to cancer: Familial Adenomateous Polyposis (FAP), a rare genetic disease characterized by the development of polyps on the colon; Barrett's Esophagus, a disorder caused by acid reflux; and squamous carcinoma of the esophagus, caused mainly from smoking.

"The goal is to see if berries can inhibit cancer development by reducing the growth rate of precancerous cells," said Stoner. "If this works in humans, there will be a tremendous demand for berries. This will be just the beginning."

Candace Pollock
Dick Funt