Josh Vander Weide and Paolo Sabbatini*
*Michigan State University, 426 Auditorium Road, East Lansing, MI 48824 (sabbatin@msu.edu)

Winegrape (Vitis vinifera L.) is the most widely cultivated fruit crop in the world. However, climate characteristics in some growing regions are suboptimal for grape production, including short season length and excess precipitation. Grapegrowers can utilize an array of methods to mitigate these issues, including “early leaf removal,” a management practice involving removal of leaves from selected basal nodes along shoots around bloom. This meta-analysis reviews the extensive literature on this prac- tice, with specific regard to application at “prebloom” (PB). One hundred seventy-five publications on the topic of “early leaf removal” were identified using key terms and subsequently narrowed via eight data curation steps. The comparison between treated (PB) and control plants in these studies revealed two important results. First, PB lowered bunch rot disease (-61%), partially through reducing the compactness of clusters. Second, PB promoted a significant increase in fruit total soluble solids (Brix, +5.2%), which was related to the increase in leaf-to-fruit ratio. Furthermore, cultivar and rootstock were found to have a large influence on the success of PB, while the contribution of climate was smaller. PB significantly lowers yield and bunch rot disease and increases Brix, both of which improve grape and wine quality.

Funding Support: AgBio-Research at Michigan State University (Project GREEEN) and the Michigan Craft Beverage Council