Abstract Boxwood (Buxus spp.) blight is a devastating disease caused by the Ascomycete fungus Calonectria pseudonaviculata in the U.S. and Europe. A second Calonectria species, C. henricotiae, is also pathogenic on boxwood in Europe, but is not present in the U.S. where it is classified as a quarantine pathogen. Composting can eradicate various plant pathogens and high temperature is likely the most important factor influencing pathogen eradication. We previously reported that C. pseudonaviculata microsclerotia survived exposure to 40 °C in an incubator without compost, whereas exposure to the same temperature and time, but with compost added, greatly decreased survival. That is, the decrease in Calonectria growth and survival in compost was greater than could be accounted for by high temperature alone. We hypothesized that the enhanced decrease in Calonectria growth and survival might be due to ammonia, a fungitoxic gas produced during composting. In this laboratory study, we determined that ammonia within agar in Petri plates reduced radial growth of both C. pseudonaviculata and C. henricotiae. In studies with C. pseudonaviculata, gaseous ammonia reduced microsclerotia survival. Our findings suggest that composting dead or dying blighted boxwoods in the presence of ammonia could reduce dissemination of both Calonectria species from blighted to healthy boxwoods.

中文翻译：

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堆肥过程中氨对黄杨枯萎病病原体 Calonectria pseudonaviculata 和 C. henricotiae 的影响

摘要 黄杨（Buxus spp.）疫病是由子囊菌Calonectria pseudonaviculata 在美国和欧洲引起的一种破坏性疾病。第二种 Calonectria 物种 C. henricotiae 在欧洲也对黄杨木具有致病性，但在美国不存在，在那里它被归类为检疫病原体。堆肥可以根除各种植物病原体，高温可能是影响病原体根除的最重要因素。我们之前曾报道过，在没有堆肥的情况下，C. pseudonaviculata microsclerotia 在 40 °C 的孵化器中存活下来，而暴露于相同的温度和时间，但添加了堆肥，大大降低了存活率。也就是说，堆肥中 Calonectria 生长和存活率的下降大于单独高温所能解释的。我们假设 Calonectria 生长和存活率的下降可能是由于氨，一种在堆肥过程中产生的真菌毒性气体。在这项实验室研究中，我们确定培养皿中琼脂中的氨减少了 C. pseudonaviculata 和 C. henricotiae 的径向生长。在对 C. pseudonaviculata 的研究中，气态氨降低了微菌核的存活率。我们的研究结果表明，在氨存在的情况下对死亡或垂死的枯萎黄杨木进行堆肥可以减少两种 Calonectria 物种从枯萎黄杨木到健康黄杨木的传播。假舟状，气态氨降低了微菌核的存活率。我们的研究结果表明，在氨存在的情况下对死亡或垂死的枯萎黄杨木进行堆肥可以减少两种 Calonectria 物种从枯萎黄杨木到健康黄杨木的传播。假舟状，气态氨降低了微菌核的存活率。我们的研究结果表明，在氨存在的情况下对死亡或垂死的枯萎黄杨木进行堆肥可以减少两种 Calonectria 物种从枯萎黄杨木到健康黄杨木的传播。