Good Fruit Grower

July 1

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Low-chill cherry A new selection has resistance to doubling and better color and size than Brooks. by Geraldine Warner Cherry breeder David Cain checks the fruit of a new cherry variety he has developed that consistently produces high quality fruit even in the hotter growing regions of California. new, high-quality, low-chill sweet cherry variety developed specifically for the hot growing areas of California, could be available for growers to plant within a couple of years. Dr. David Cain, breeder at International Plant Genetics of Bakersfield, California, is applying for a patent on a cherry that requires less chill than the varieties currently produced in the San Joaquin Valley. Trees exposed to insufficient chill hours tend to bloom late and over a longer period of time, and fruit set is poor. One of Cain's objectives, when he established the company in 2001, was to develop early-season, low-chill cherries that produce consistently every year and don't require chemicals to bring them out of dormancy. Typically, growers use Dormex (hydrogen cyanamide) or potassium nitrate to help break dormancy of the varieties they're currently growing. Developing varieties with resistance to doubling was another goal. Cherries tend to produce doubles, beaks, or sutures the following season when they're exposed to high temperatures during flower bud initiation. Brooks, one of the primary cherries grown in that area, is particularly sensitive to doubling. The new cherry that is being patented ripens just ahead of Brooks and has darker flesh and skin than Brooks, which is a paler color than optimal. It's also a little larger than Brooks. Cain said trees could be available in a couple of years. Expanding production The cherry industry has been rapidly expanding in the Bakersfield area, but currently, only a limited number of varieties can be grown there. These include Tulare and Sequoia, as well as Brooks. But even these varieties are not consistently productive in those conditions, Cain said. "We have a very low crop this year because of the lack of chill," he said. For his crosses, Cain has used germplasm from Spain and Greece, and vari- eties from the University of Florida that were developed using several wild species of cherries from Taiwan. Along with the low-chill characteristic, promis- ing new cherries must have high eating quality. Identifying selections that have all those traits takes time, Cain said. "It's a pretty slow process because they take so long to come into production," he said. "It's five to six years before you see fruit on the seedlings." The company has between 30,000 and 40,000 cherry seedlings in the field in Bakersfield, making it one of the largest cherry breeding efforts in the world. Each year, some seedlings are discarded, and more are planted. Dr. Bob Andersen, retired stone fruit breeder at Cornell University, New York, is helping to evaluate the cherry selections, as Cain also breeds grapes. Low-chill is a complex trait for which there is currently no genetic marker that would enable the breeder to eliminate selections that don't have the trait before they're planted out in the field, Cain said. The company has several other promising selections that might be released within the next year or two if they continue to do well in evaluations. They include some blush varieties. Cain said there is some interest in early-market blush cherries, but it is limited because most cherries grown in California are trucked to the Stockton area for packing, and blush cherries would be vulnerable to bruising. Some selections with interesting traits that produce a few too many doubles or have too high a chill require ment for California are being tested in the cooler conditions of Washington State. • Cris Hales Fruit Procurement & Grower Services 14 JULY 2012 GOOD FRUIT GROWER 1-800-548-4691 PHOTO COurTesy OF DaviD Cain

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