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56 p r a c t i c a l w i n e r y & v i n e ya r d J U n e 2 0 1 4 g r a p e g r o w i n g stages such as bloom. To address this concern, we quantified the number of damaged clusters following each leaf removal pass. The type of damage caused by the mechanical leaf puller var- ied with when leaf removal was performed. Bloom leaf removal resulted in removal of tips of some clusters, and leaf removal at pea-size or bunch closure resulted in berry splitting on only the smallest clusters. No clusters were completely removed by the mechanical leaf puller. Damage to clusters appeared to be less when leaf removal was initiated at later stages of development, but this was not statisti- cally significant (p=0.1607). Physical damage was greater in the mechanical leaf removal treatments (with 6.9% of clusters per vine damaged, on average) than in hand-removal treatments, which had only 0.5% of clusters damaged (p<0.0001). At most, only two clusters per vine were damaged in the mechanical treatments that were considered to be of little practical concern. When visually comparing vineyards that are mechanically and manually leaf removed, the two often appear quite different with respect to the openness of the cluster zone, particularly when trying to clear both sides of the canopy. However, when the amount of leaf area remaining on vines after each time point of leaf removal was quantified in the study, there was no difference in hand and mechanical leaf removal except during the earliest phenological stage (bloom). Hand leaf removal vines had 28% lower leaf area per shoot (p=0.0109) than vines receiving mechanical leaf removal at bloom (Figure 1). This is likely due to the smaller canopy size as compared to later stages. Later in the summer, shoot leaf area at bunch closure was quantified, and there were no differences between the leaf area remaining by timing or method of leaf removal. As expected, there were no differences in vine pruning weight at the end of the growing season. Adequate canopy was maintained in all treatments, and vine vigor was not impacted by the amount of leaf removal performed. The leaf removal method and timing did not influence berry ripening in 2011. There were no differences in basic maturity indices (TSS, pH or TA) or in berry anthocyanin, phenolic or tannin concentrations at harvest. Other leaf removal studies conducted in the Willamette Valley of Oregon from 2008 to 2012 found similar results with respect to fruit maturity. Results of the 2011 trial did not show differ- ences in anthocyanins (color) with earlier leaf removal. Research conducted by J. Lee and P. Skinkis where leaf removal was conducted at different phenological stages on both sides of the canopy showed greater anthocyanins with bloom time leaf removal when compared to removal at bunch closure. 2 Differ- ences may be due to vine canopy differences, season or clone. Considerations Leaf removal is an important practice in vineyard management. However, the best use of this technique depends on production goals and site-specific characteristics of the vineyard. Based on four years of leaf-removal research conducted in the Willamette Valley, it is apparent that conducting leaf removal earlier in the season can keep fungal pathogens at minimum (Skinkis and Mahaffee, unpublished). The greatest impact on fungal diseases was found in years with high disease pressure (2010–11). In years such as 2013, which started out dry and warm, less aggressive leaf removal was gen- erally applied to avoid berry sunburn or heat exposure. This may have made conditions for Botrytis worse later in the season with