Choke disease, which is caused by Epichloë typhina, was first reported in orchardgrass seed production fields in the Willamette Valley, Oregon in 1997 and has continued to persist in the system. The disease can cause up to 30% losses in seed yield. Unlike many Epichloë species that are seed transmitted, it is unclear how infection of orchardgrass by E. typhina occurs in the field, or how the disease spreads within plants. In this study, the overall incidence of choke on trap plants placed in a choke-infested field was 41% in 2018 and 9% in 2019. Similar incidence of infection occurred when exposed before (39%) or after (43%) swathing in 2018. Contrary to our hypothesis, plants sprayed with an artificial honeydew had a significantly lower incidence of infection (32%) when compared to the controls (48%). An examination of the spread of E. typhina within tillering plants revealed that development of infected tillers was greater than development of uninfected tillers, which could contribute to the gradual increase in choke in fields over time. These studies contribute to a better understanding of how choke is spread within plants and in orchardgrass seed production fields, which is an important step towards developing control methods to reduce choke in orchardgrass seed production fields.

1997 年在俄勒冈州威拉米特谷的果园种子生产田首次报道了由伤寒杆菌引起的窒息病，并在该系统中持续存在。该病害可导致种子产量损失高达 30%。与许多通过种子传播的Epichloë物种不同，尚不清楚E. typhina 如何感染果园草发生在田间，或疾病如何在植物内传播。在这项研究中，2018 年和 2019 年，放置在受窒息影响的田地中的诱捕植物的总体窒息发生率分别为 41% 和 9%。类似的感染发生率在暴露之前 (39%) 或之后 (43%) 2018. 与我们的假设相反，与对照组 (48%) 相比，喷洒人造蜜露的植物的感染率 (32%) 显着降低。检查E. typhina的传播在分蘖植物内显示，受感染分蘖的发育大于未受感染分蘖的发育，这可能导致随着时间的推移田间阻塞逐渐增加。这些研究有助于更好地了解窒息如何在植物和果园种子生产领域传播，这是开发控制方法以减少果园种子生产领域窒息的重要一步。