Good Fruit Grower

May 15

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24 MAY 15, 2015 GOOD FRUIT GROWER QUALITY O regon State University researchers have found that pre- and postharvest appli- cation of calcium can improve the ocean shipping quality of sweet cherries. As export markets become more import- ant because of the expanding Pacifi c Northwest cherry crop, more cherries will be shipped by ocean, a trip that can take several weeks. Sweet cherries shipped to distant markets are subject to various arrival problems, including fruit softening, flavor loss, skin darkening, pitting, splitting, decay, and stem and pedicel browning. Dr. Yan Wang, post- harvest physiologist at OSU's Mid-Columbia Agricultural Research and Extension Center in Hood River, has found ways to reduce pitting, one of the more important storage issues. Sweet cherries have high respiration rates and are highly susceptible to mechanical damage, Wang said during a winter cherry meeting in the Northwest. Pitting, which can be caused by heat and mechanical damage, results from peel depression that occurs after the fruit's mesocarp cell layers die and dry. Pitting from mechani- cal damage (dropping) has been shown to occur during harvesting, when hauling from fi eld to packing house, and during packing. Additionally, cold fruit are more susceptible to pitting, as are some varieties, like Skeena and Sweetheart. Calcium plays a key role in the fruit's cell wall struc- ture and strength and respiration. However, fruit are often defi cient in calcium due to its low mobility in plants. Acid soils, high growing temperatures, water stress, high humidity, wide fl uctuation in soil moisture, low crop load, and high nitrogen and potassium levels can all contribute to low calcium levels in fruit. Wang sampled Skeena and Sweetheart cherries from four commercial orchards and found fruit calcium levels ranging from 300 to 600 parts per million dry weight. "In the survey, fruit that had higher calcium concentrations were also the firmest and had the least amount of pitting," he said. "Cherries with higher calcium content tend to ship better and have better storage potential than those that have lower calcium levels," Wang said. The diffi culty is fi nding a way to quickly boost calcium levels in the fruit. In trials over the last several years, Wang explored improving cherry shipping quality by increasing fruit tis- sue calcium content through preharvest calcium sprays and adding calcium during postharvest hydro-cooling. Both methods show potential. For the preharvest calcium sprays, he studied Lapins Calcium improves Cherries PHOTOS COURTESY OF YAN WANG Skeena cherries after three weeks of storage on the left are from an orchard with high tissue calcium content of about 600 ppm. Cherries on the right are from an orchard with low tissue calcium content of 400 ppm after three weeks of cold storage. High calcium content Low calcium content Calcium in fi eld sprays and added to cooling water reduced pitting and improved cherry fi rmness. by Melissa Hansen Consider for your next planting: • BRUCE PONDER • SUSAN WILKINSON • ADAM WEIL • DAVE WEIL 503-538-2131 • FAX: 503-538-7616 BENEFITS: • Disease tolerant • Cold hardy • Adapts well to all cherry-growing districts • Forms flower buds and comes into bearing quicker than Mazzard with a better distribution of flower buds Now booking orders for 2016 Call Tree Connection: 800-421-4001 Dwarfing Cherry Rootstock Krymsk ® 5 Krymsk ® 6 [cv. VSL-2, USPP 15,723] [cv. LC-52, USPP 16,114] "Krymsk ® 5 and Krymsk ® 6 cherry rootstocks have proven to be the best rootstock for our orchards. They are yield efficient, grow and adapt well, and are cold hardy." —John Morton The Dalles, Oregon

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