Abstract

Powdery mildew on cannabis (Cannabis sativa L., marijuana), caused by Golovinomyces cichoracearum, reduces plant growth and overall quality. To investigate disease management options, biological, chemical and physical approaches were assessed. A mildew-susceptible strain, ‘Copenhagen Kush’, was grown indoors with continual exposure to mildew inoculum. Treatments were applied weekly over a four-week period to groups of four plants once mildew infection had established itself. Trials were repeated thrice under varying initial disease pressures. Disease assessments were made weekly and the percentage of area infected on 30 leaflets per plant was used to calculate a disease rating score for treated and control plants. Disease progress curves were plotted and AUDPC values were determined for each treatment. To test the effect of UV-C light on mildew development, plants were exposed daily for 3–5 s over 28 days to UV-C light. The response of 12 cannabis strains to powdery mildew infection was assessed after exposing them to inoculum over a period of two weeks. The most effective treatments that significantly (P < 0.05) reduced disease in three trials were Luna Privilege SC (fluopyram), Regalia^® Maxx, MilStop^®, Rhapsody ASO^TM, neem oil, and Stargus^®. Treatments that were less effective included ZeroTol^®, boric acid, and Actinovate^® SP. Daily exposure of plants to UV-C light significantly reduced disease (by 45.2%, P < 0.05). Seven of 12 cannabis strains had significantly lower disease severity compared with the other five strains. The disease management strategies evaluated in this study have potential for reducing powdery mildew development on cannabis.

摘要

由Golovinomyces cichoracearum引起的大麻上的白粉病（Cannabis sativa L., 大麻），降低植物生长和整体质量。为了研究疾病管理选项，评估了生物、化学和物理方法。一种易受霉菌影响的菌株“哥本哈根库什”在室内生长，并持续接触霉菌接种物。一旦霉菌感染已经建立，在四个星期的时间内每周对四株植物进行处理。试验在不同的初始疾病压力下重复三次。每周进行一次病害评估，并使用每株植物 30 片传单上感染的面积百分比来计算处理植物和对照植物的病害评分。绘制疾病进展曲线并确定每次治疗的 AUDPC 值。为了测试 UV-C 光对霉菌发展的影响，植物在 28 天内每天暴露于 UV-C 光下 3-5 秒。在将 12 种大麻菌株暴露于接种物两周后，评估了它们对白粉病感染的反应。最有效的治疗方法显着（P < 0.05) 在三个试验中减少了疾病，包括 Luna Privilege SC（氟吡菌酰胺）、Regalia ^® Maxx、MilStop ^®、Rhapsody ASO ^TM、印楝油和 Stargus ^®。效果较差的治疗包括 ZeroTol ^®、硼酸和 Actinovate ^® SP。植物每天暴露在 UV-C 光下可显着减少疾病（降低 45.2%，P < 0.05）。与其他 5 种大麻菌株相比，12 种大麻菌株中有 7 种的疾病严重程度显着降低。本研究中评估的疾病管理策略具有减少大麻白粉病发展的潜力。