RT Journal Article SR Electronic T1 Impact of Severity and Timing of Basal Leaf Removal on 3-Isobutyl-2-Methoxypyrazine Concentrations in Red Winegrapes JF American Journal of Enology and Viticulture JO Am J Enol Vitic. FD American Society for Enology and Viticulture SP 358 OP 364 DO 10.5344/ajev.2010.61.3.358 VO 61 IS 3 A1 Scheiner, Justin J. A1 Sacks, Gavin L. A1 Pan, Bruce A1 Ennahli, Said A1 Tarlton, Libby A1 Wise, Alice A1 Lerch, Steven D. A1 Vanden Heuvel, Justine E. YR 2010 UL http://www.ajevonline.org/content/61/3/358.abstract AB Field studies were conducted on Vitis vinifera L. cvs. Cabernet franc and Merlot to evaluate the effects of basal leaf removal timing and severity on 3-isobutyl-2-methoxypyrazine (IBMP) concentration in grape berries. Treatments consisted of removing either 50% or 100% of leaves from the fruiting zone at either 10 days after anthesis, 40 days after anthesis, or 60 days after anthesis. In the second year of the Cabernet franc study, a 15-day postveraison leaf removal treatment was also included. In both years of the Cabernet franc study, significant reductions in IBMP (range = 28 to 53%) were observed before veraison compared with the control in both 10 days after anthesis treatments (50% and 100% leaf removal). In 2007, all leaf removal treatments significantly reduced IBMP concentrations compared with the control (46 to 88%) in Cabernet franc berries at harvest, with the greatest reduction observed in the 100% leaf removal treatments at 10 days after anthesis and 40 days after anthesis. In 2008, the 100% leaf removal treatment at 10 days after anthesis and the 50 and 100% leaf removal treatments at 40 days after anthesis significantly reduced IBMP concentrations (34 to 60%) in mature Cabernet franc berries. In the Merlot trial, all leaf removal treatments significantly reduced IBMP concentrations (38 to 52%) at harvest. In summary, early season (10 to 40 day after anthesis) basal leaf removal reduced IBMP accumulation preveraison compared with the control in both studies, suggesting that early leaf removal is a more effective management strategy to reduce IBMP accumulation in grape berries than leaf removal later in the season.