Issue link: http://read.dmtmag.com/i/728583
20 OCTOBER 2016 Good Fruit Grower www.goodfruit.com on many difenoconazole-containing products include warnings about their use on hybrid varieties, such as cold-hardy cultivars. Overall, she was pleased — and somewhat surprised — that the cold-hardy varieties performed so well. "I was expecting to see more of the cultivars react to the fungi- cides, because we were using high rates of copper and sulfur that were right at the upper limit of what's recom- mended on the label," McManus said. While they were spraying about every two weeks, she explained that most growers would probably restrict the spraying to a couple of times a year for fungicide resistance management and perhaps one extra spray of sulfur later in the season to control powdery mildew. Tracking leaf nutrients Rosen's project on nutrition involves researchers from five universities and includes 16 sites, mainly in the upper Midwest. "We concentrated on the cold- hardy cultivars Frontenac, Marquette and La Crescent, collected tissue samples either at bloom or at veraison, which are the recommended times for grape production, plus one additional time in between, and developed a background database," he said. They also gathered data on grape yields and juice quality. The tissue samples provide insight that soil testing alone cannot, he said. "The problem with soil tests for established vineyards is that grape roots are prolific and explore large amounts of soil, so while soil tests provide initial information about the site for planting, we think that the tissue tests integrate what is going on in fruiting vines a little bit better." By analyzing all of the collected tissue-testing data, he said, they hope to come up with average nutrient values for the three varieties, as well as sufficiency ranges, which would give growers target nutrient ranges for good vine growth and juice quality. "For instance, if your potassium is low in the leaf tissue, you would need to look at perhaps amending the soil to increase that nutrient," he said. Preliminary results suggest that whole-leaf sampling may be a better gauge of tissue-nutrient level than the common technique of sampling only the petiole (the leaf stem). "We're still looking at the data so we don't want to draw definite conclusions quite yet, but we're finding that sampling the whole leaf or blade tissue at bloom seems to be a relatively good indicator of yeast-assim- ilable nitrogen," he said. In addition, their early analy- ses suggest that vine nitrogen affects yeast-assimilable PHOTO BY JAMES CRANTS/UNIVERSITY OF MINNESOTA Field researchers harvest grapes at one of the locations in the nutrition study. The research group hopes to provide growers with nutrient sufficiency ranges for Frontenac, Marquette and La Crescent. TRACTORS HARVEST RENTAL RETURNS AGROPLUS V/S/F SERIES – Engine power from 82 to 106hp – Transmission speeds 30+15 or 45+45 – ROPS & Cabs, either standard or low profile – Standard front and rear brakes for maximum safety – Standard front and rear diff locks for full four wheel drive engagement – 3 hydraulic remotes w/ flow control – As narrow as 44" overall width – Ecoline series for superior value 4857 Contractors Dr. East Wenatchee (509) 886-1566 • (800) 461-5539 www.valleytractor.com Model 420f $39,999 * 4WD, 89hp PTO #3002 - 369 hours *Price does not include 3 pt. hitch