Understanding bud rot development, caused by Botrytis cinerea, on cannabis (Cannabis sativa L.) plants grown under greenhouse conditions

Botrytis cinerea is a widespread necrotrophic plant pathogen that causes diseases on >1000 plant species, including vegetables and ornamental greenhouse crops. On cannabis ( Cannabis sativ a L.), the pathogen is responsible for causing “bud rot”, a major disease affecting the inflorescences (compound flowers), as well as seedling damping-off and leaf blight under certain conditions. During greenhouse cultivation, Botrytis cinerea can destroy cannabis inflorescences rapidly under optimal relative humidity conditions (>70%) and moderate temperatures (17–24 °C). Little is currently known about the host–pathogen interactions of Botrytis cinerea on cannabis. Information gleaned from other hosts can provide valuable insights for comparative purposes to understand disease development, epidemiology, and pathogenicity of Botrytis cinerea on cannabis crops. This review describes the pathogenesis and host responses to Botrytis infection and assesses potential mechanisms involved in disease resistance. The effects of microclimatic and other environmental conditions on disease development, strategies for early disease detection using prediction models, and the application of biological control agents that can prevent Botrytis cinerea development on cannabis are discussed. Other potential disease management approaches to reduce the impact of Botrytis bud rot are also reviewed. Numerous opportunities for conducting additional research to better understand the cannabis– Botrytis cinerea interaction are identified.