2478:
The Effect of Foliar Nitrogen Application On Juice Yeast Available Nitrogen In ‘Riesling' Depends On Vine Nitrogen Status
Tuesday, July 28, 2009: 11:00 AM
Jefferson C (Millennium Hotel St. Louis)
Tim Martinson, Department of Horticultural Science, Cornell Univ, Geneva, NY
Insufficient yeast available nitrogen (YAN) is a major cause of sluggish fermentation in wine production, and is also associated with a wine disorder called “atypical aging”. The objective of this study was to determine if foliar application of nitrogen can be used to improve YAN in grape must. Three levels of foliar N (0, 3, 5 times of foliar N sprays) in combination with three levels of soil N (0, 25, or 50 lb actual N/acre) were tested on filed-grown ‘Riesling’/3309 in a factorial design over two years. For soil N treatments, two split applications, 25 lb N at 2 weeks before bloom and 25 lb N one week after bloom, were made for the 50 lb N treatment, whereas all N was applied at 2 weeks before bloom for the 25 lb N treatment. Foliar N sprays (5.5 lb of urea/100 gal water) were centered on veraison at weekly intervals. Foliar N applications significantly increased juice YAN during the 2004 wet season, and 3 times of foliar spray appeared to be as effective as 5 times of foliar spray treatment whereas soil N application didn’t have any effect. In the 2005 warm and dry season, vine background N status and juice YAN were significantly lower than in 2004. Foliar N sprays were more effective in increasing juice YAN compared with 2004. Soil N application also improved vine N status and slightly increased juice YAN. These results indicate that there is a greater need for foliar N application in a dry year and the effect of foliar N spray on juice YAN is larger in a dry year.
