Knowledge-Based Integrated Management of Botrytis Bunch Rot of Grapevine Caused by <i>Botrytis cinerea</i> in a Northern Climate

In this study, we evaluated the efficacy of control methods against Botrytis bunch rot (BBR) and explored the integration of several control methods. Among the biological control agents, Aureobasidium pullulans (Botector) demonstrated the best efficacy, with an average reduction in BBR of 57% (86% reduction in BBR for the synthetic fungicides). With the exception of leaf removal at the fruit set stage (71 on the BBCH scale) on one row side only, leaf removal on both row sides at stage 71 and on one and two row sides at the early flowering stage (63 on the BBCH scale) significantly reduced the percent BBR at harvest (23.6, 21.8, and 15.1%, respectively) compared with the control without leaf removal (48.2%). Of the 10 BBR management programs, the programs that kept the BBR below the economic threshold of 5% bunch area diseased at harvest were, for the susceptible cultivar Seyval Blanc, trash management combined with leaf removal at stage 63 on both row sides combined with application of synthetic fungicides at fixed intervals (3.9%), synthetic fungicides applied based on risk of BBR (4.3%), or application of Botector according to the risks of BBR (4.5%). With respect to Vidal Blanc, a moderately susceptible cultivar, for these management programs, the severity of BBR at harvest was 4.5, 4.7, and 4.9%, respectively. The results showed that by using integrated BBR management it is possible to maintain the disease below 5% without synthetic fungicides or with a reduced number of applications. [Formula: see text] Copyright © 2025 His Majesty the King in Right of Canada, as represented by the Minister of Agriculture and Agri-Food Canada. This is an open access article distributed under the CC BY-NC-ND 4.0 International license .