Good Fruit Grower

October 2016

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Page 20 of 47 Good Fruit Grower OCTOBER 2016 21 nitrogen (YAN) and potassium influences juice pH. The research group has finished its number crunch- ing and will soon be able to provide growers with nutri- ent sufficiency ranges for Frontenac, Marquette and La Crescent. While this type of information is critical for under- standing these northern varieties, Rosen said growers should keep in mind that nutrition level is just one part of a bigger picture. "There are many factors beyond nutri- tion that affect juice quality, but this study will give us a little more data to help grow cold-hardy cultivars." Both Rosen and McManus lauded the Northern Grapes Project and its focus on cold-hardy varieties. Rosen remarked, "There just hasn't been any work done on these cold-hardy cultivars, so we are having to rely mostly on nutrition studies that had been done on Vitis vinifera or Vitis labrusca types. The Northern Grapes Project gives us the opportunity to see if there are actu- ally any differences and determine whether we need to change any of the diagnostic tools that are being used for cold-hardy grape nutrition." McManus describes the Northern Grapes Project as "hugely important," particularly in providing base infor- mation to the growing number of people just entering the grape industry in cool climates. "The timing has been really good." The end of the Northern Grapes Project later this year, however, does not mean the end of research on cold- hardy grapes, she said. Her research group, for instance, is now trying to fill another major knowledge gap related to these varieties: One of her graduate students, David Jones, is conducting replicated trials to do an analysis of their disease resistance and provide susceptibility ratings. This will be another step toward providing growers with information that is based on careful studies of these cold-hardy cultivars. She added, "One of our main goals is to remove some of those question marks in the exten- sion literature and replace anecdotal observations with real scientific data." • The variety Brianna was the most sensitive to copper of the 15 cold-hardy varieties in McManus' trials. Just one or two sprays of the copper fungicide caused a reaction. PHOTOS BY PATRICIA MCMANUS This Maréchal Foch shows severe sulfur injury/defoliation in the left cordon. The right cordon, which was treated with copper, is fine. Swiss Precision. Made to Last New Curved Blade Pull-stroke Saws Felco 640 & 630 Saw locks securely in leg sheath Reinforced tooth tips Leg sheath suits either side of body Ergonomic handle fits right or left hands Blade stop prevents saw escape High efficiency curved blade 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 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 2017 ROOTS AVAILABLE NOW Call Tree Connection: 800-421-4001

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