TY - JOUR T1 - Impact of Grape Cluster Division on Cluster Morphology and Bunch Rot Epidemic JF - American Journal of Enology and Viticulture JO - Am. J. Enol. Vitic. DO - 10.5344/ajev.2012.12041 SP - ajev.2012.12041 AU - Daniel Molitor AU - Marc Behr AU - Lucien Hoffmann AU - Danièle Evers Y1 - 2012/08/17 UR - http://www.ajevonline.org/content/early/2012/08/16/ajev.2012.12041.abstract N2 - Manual horizontal cluster division may constitute an efficient tool to optimize wine quality. To test this hypothesis and to determine the optimal timing of this viticultural practice, examinations investigating the impact of cluster division on (i) the cluster morphology, (ii) the bunch rot disease severity, as well as (iii) the harvest parameters such as yield and total soluble solids were conducted on the white Vitis vinifera L. cultivars Pinot gris and Riesling in the Luxembourgish winegrowing region in the years 2010 and 2011. Treatments were applied at five different time points between pre-bloom (BBCH 57) and veraison (BBCH 81). In both varieties, all post-bloom cluster division treatments were able to loosen the cluster structure and to reduce the bunch rot disease severity. The later cluster division took place, the more pronounced were the effects on cluster structure. The density index turned out to be a suitable parameter to describe the cluster structure and the predisposition to bunch rot infestation. Cluster division resulted in yield reductions (up to 30%), which increased with time after flowering. Post-bloom cluster division enabled optimizing wine quality by (i) improving grape maturity due to crop load reduction, (ii) reducing fungal contamination and (iii) improving grape quality through the possibility to elongate the ripening period. Consequently, post-bloom horizontal cluster division can be recommended as an efficient crop cultural tool for premium wine production under cool climate conditions. ER -