Carrot cultivar response to foliage side trimming for suppression of Sclerotinia rot

Foliage side trimming opens the carrot canopy, permitting greater sunlight penetration and airflow. This prevents moisture build-up and creates unfavourable conditions for the development of common carrot pathogens such as Sclerotinia sclerotiorum (Lib.) de Bary. This study was carried out at the Agriculture and Agri-Food Canada Harrington Research Farm in the growing seasons of 2007, 2008 and 2009, to examine cultivar yield response to foliage side trimming and suppression of Sclerotinia rot of carrot (SRC). All plots were assessed for disease incidence at the time of trimming and again at harvest. As well, carrots were placed into storage at 10 °C for three months to assess the incidence of infected roots. Cultivars varied in yield and other biological parameters, including susceptibility to SRC. Across cultivars, side foliage trimming significantly reduced total and marketable yield by approximately 7.5 and 9.1%, respectively. Overall, side foliage trimming significantly reduced the number of petioles with SRC at both the September and harvest assessments. The incidence of stored roots with SRC was also significantly reduced by side foliage trimming in one year of the study. Disease management strategies for SRC could include selection of cultivars with low disease susceptibility and use of side foliage trimming to reduce disease incidence in susceptible cultivars that are grown for specific agronomic traits. © 2013 Her Majesty the Queen in Right of Canada.