Tjosvold S A, Chambers D L, Fichtner E J, Koike S T, Mori S R
University of California Cooperative Extension, Watsonville.
Department of Plant Pathology, University of California, Davis.
Plant Dis. 2009 Apr;93(4):371-376. doi: 10.1094/PDIS-93-4-0371.
Phytophthora ramorum has been found in potting media of containerized plants; however, the role of infested media on disease development under nursery conditions is unknown. This study assesses pathogen survival, sporulation, and infectivity to rhododendron plants in nursery pots with infected leaf litter that were maintained under greenhouse and field conditions. The influence of environmental conditions and irrigation method on disease incidence was also assessed. Infected leaf disks were buried below the soil surface of potted rhododendrons and retrieved at approximately 10-week intervals for up to 66 weeks. Pathogen survival was assessed by either isolation or induction of sporulation in water over three experimental periods. P. ramorum was recovered from infected leaf disks incubated in planted pots for longer than 1 year. Chlamydospores and sporangia formed on hydrated leaf disks but relative production of each spore type varied with the duration of incubation in soil. Root infections were detected after 40 weeks in infested soil. Foliar infections developed on lower leaves but only after spring rain events. Sprinkler irrigation promoted the development of foliar infections; no disease incidence was observed in drip-irrigated plants unless foliage was in direct contact with infested soil. Management implications are discussed.
在容器栽培植物的盆栽介质中发现了栎叶疫霉；然而，受侵染的介质在苗圃条件下对病害发展的作用尚不清楚。本研究评估了在温室和田间条件下，带有感染性落叶的苗圃花盆中，病原体对杜鹃花植株的存活、产孢和侵染力。还评估了环境条件和灌溉方式对发病率的影响。将感染的叶盘埋在盆栽杜鹃花的土壤表面以下，每隔约10周取回一次，最长持续66周。在三个实验阶段，通过分离或在水中诱导产孢来评估病原体的存活情况。从种植花盆中培养超过1年的感染叶盘中分离出了栎叶疫霉。在水合叶盘上形成了厚垣孢子和孢子囊，但每种孢子类型的相对产量随在土壤中的培养时间而变化。在受侵染的土壤中40周后检测到根部感染。较低叶片上出现叶部感染，但仅在春雨过后。喷灌促进了叶部感染的发展；滴灌植物未观察到发病率，除非叶片直接接触受侵染的土壤。讨论了管理方面的意义。
