RT Journal Article SR Electronic T1 Modeling Impacts of Viticultural and Environmental Factors on 3-Isobutyl-2-methoxypyrazine in Cabernet franc Grapes JF American Journal of Enology and Viticulture JO Am. J. Enol. Vitic. FD American Society for Enology and Viticulture SP ajev.2011.11002 DO 10.5344/ajev.2011.11002 A1 Justin J. Scheiner A1 Justine E. Vanden Heuvel A1 Bruce Pan A1 Gavin L. Sacks YR 2011 UL http://www.ajevonline.org/content/early/2011/10/11/ajev.2011.11002.abstract AB A study was conducted to determine the key environmental and viticultural variables affecting the concentration of 3-isobutyl-2-methoxypyrazine (IBMP) in Cabernet franc grapes. Berries were sampled from individual vines at 30 days after anthesis (DAA), 50 DAA, and harvest from ten and eight commercial New York State vineyards in 2008 and 2009, respectively. IBMP concentrations at 50 DAA were significantly higher in the warmer 2008 growing season (2008 range = 103 to 239 pg/g; 2009 range = 12 to 87 pg/g). However, in the cooler 2009 growing season a smaller percent decrease in IBMP during the period from 50 DAA to harvest was observed, so that IBMP at harvest was not significantly different between years (2008 range = 1 to 13 pg/g; 2009 range = 5 to 14 pg/g). IBMP accumulation up to 50 DAA and log-fold decrease of IBMP from 50 DAA to harvest was modeled as a function of >120 viticultural and environmental variables (122 in 2008 and 140 in 2009). Important variables identified for modeling IBMP at 50 DAA were those associated with vine vigor, which was positively correlated with IBMP accumulation. Cluster light exposure did not explain differences in IBMP accumulation across sites, but it was important for modeling smaller differences within some sites. IBMP decrease could not be satisfactorily modeled across multiple sites, but within sites, the decrease was most consistently correlated with classic fruit maturity indices (total soluble solids (TSS), TSS*pH2). The intensity of herbaceous aromas in wines produced from each site was not correlated with IBMP concentration, but multivariate models indicated that lower vine water status was the best predictor of increased herbaceousness.