Abstract

Bud rot pathogens cause diseases on Cannabis sativa L. (cannabis, hemp) worldwide through pre- and post-harvest infections of the inflorescence. Seven indoor or outdoor cannabis production sites and three hemp fields were sampled for bud rot and stem canker presence during 2019–2020. Among 178 isolates recovered from diseased tissues, sequences of the ITS1-5.8S-ITS2 region of rDNA, the glyceraldehyde-3-phosphate dehydrogenase (G3PDH) gene and the heat shock 60 (HSP) gene identified the following: Botrytis cinerea (162 isolates), B. pseudocinerea (2), B. porri (1), Sclerotinia sclerotiorum (5), Diaporthe eres (3) and Fusarium graminearum (5). Pathogenicity studies conducted on fresh detached cannabis buds inoculated with spore suspensions or mycelial plugs showed that B. cinerea, S. sclerotiorum and F. graminearum were the most virulent, while B. pseudocinerea, B. porri and D. eres caused significantly less bud rot. Optimal growth of Botrytis species occurred at 15–25°C. In vitro antagonism tests showed that Bacillus spp., Trichoderma asperellum and Gliocladium catenulatum inhibited B. cinerea and S. sclerotiorum colony growth. When applied as a spray 48 h prior to B. cinerea inoculation, all biocontrol agents significantly (P < 0.01) reduced disease development on detached inflorescences. Prolific growth and sporulation of T. asperellum and G. catenulatum were observed on bud tissues. The pathogens B. porri, S. sclerotiorum, D. eres and F. graminearum are described for the first time as cannabis bud rot pathogens. Inoculum from neighbouring fields of diseased garlic, cabbage, blueberry and hay pasture, respectively, likely initiated infection of inflorescences. Several biological control agents show potential for disease reduction through competitive exclusion.

摘要

芽腐病病原体通过花序的收获前和收获后感染在全球范围内引起Cannabis sativa L.（大麻、大麻）疾病。2019 年至 2020 年期间，对七个室内或室外大麻生产场地和三个大麻田进行了采样，以检测是否存在芽腐病和茎溃疡病。在从患病组织中回收的 178 个分离株中，rDNA 的 ITS1-5.8S-ITS2 区域、3-磷酸甘油醛脱氢酶 (G3PDH) 基因和热休克 60 (HSP) 基因的序列确定了以下内容：Botrytis cinerea（162 个分离株） ), B. pseudocinerea (2), B. porri (1), Sclerotinia sclerotiorum (5), Diaporthe eres (3) 和Fusarium graminearum(5). 对接种孢子悬液或菌丝栓的新鲜分离的大麻芽进行的致病性研究表明，B. cinerea、S. sclerotiorum和F. graminearum的毒力最强，而B. pseudocinerea、B. porri和D. eres引起的芽腐病明显较少. Botrytis物种的最佳生长发生在 15–25°C。体外拮抗作用试验表明，芽孢杆菌属，棘孢木霉和粘帚catenulatum抑制灰霉病和菌核病菌落生长。在B. cinerea前 48 小时喷洒接种后，所有生物防治剂都显着（P < 0.01）减少了分离花序的疾病发展。在芽组织上观察到T. asperellum和G. catenulatum 的多产生长和孢子形成。病原体B. porri、S. sclerotiorum、D. eres和F. graminearum首次被描述为大麻芽腐病病原体。分别来自患病大蒜、卷心菜、蓝莓和干草牧场的相邻田地的接种物可能引发了花序的感染。几种生物控制剂显示出通过竞争性排除减少疾病的潜力。