A Modified Delphi Study on Boxwood Blight Disease Management in the US Nursery Industry

Boxwood is one of the most popular evergreen shrubs in the United States, the production of which is currently challenged by boxwood blight, an emerging threat that has spread across 30 states. A thorough understanding of boxwood production, plant health, management practices and economic impact could aid in answering the needs of the nursery industry in managing this disease. An online modified Delphi survey was conducted to identify grower perceptions on processes, programs, and practices to limit or prevent the entry and spread of boxwood blight disease. The expert panel consisted of 29 nursery producers who represented a significant portion of boxwood production nationally. The panel members rated boxwood blight as the third most problematic disease with a potential to be number one in the future. Boxwood transplants were perceived as the main source of boxwood blight outbreak, followed by cutting tools, nursery equipment, containers, plant debris, irrigation water, worker hygiene, and other crops. According to the panel responses, cultural control methods, inspection, and quarantine of incoming plant material, scouting, and sanitization were the most important practices that can limit or prevent plant diseases during boxwood production. The panel members did not agree that the composted manure could influence the spread of plant disease in boxwood production, although this has been verified by the findings of various previous research experiments. Panel members were very familiar with scouting and employee training, best management practices, and the boxwood blight cleanliness program. This study documents the key components, practices, and procedures in boxwood production that could influence the spread of boxwood blight in nurseries and could be further verified by sampling and laboratory assays to specify the critical control points in the production process