Abstract Lily leaf spot is an emerging disease of the globally rare Lilium grayi S. Wats., a species endemic to the southern Appalachian Blue Ridge, USA. The species is considered Threatened or Endangered in the three states where it naturally occurs (North Carolina, Tennessee, Virginia). Disease leads to premature senescence of aboveground tissues and curtailment of sexual reproduction. Spore morphology, completion of Koch’s postulates, and DNA sequence data showed the causative agent of lily leaf spot to be Pseudocercosporella inconspicua (G. Winter) U. Braun, a Lilium-specific basidiomycete. Diagnostic disease symptomatology includes amphigenous necrotic lesions with tan to green margins encircling a white to grey powdery mass of conidia. Studies conducted in the field at Roan Mountain, NC/TN, in the largest known population, showed that a visual disease diagnosis based on morphology can be highly accurate in predicting P. inconspicua infection, and that high concentrations of conidia of P. inconspicua are strongly associated with infected L. grayi, but are largely absent or few on uninfected L. grayi and other species. Field inoculation trials using infected L. grayi leaf tissue as inocula resulted in transmission of disease and induction of premature senescence under natural conditions.

中文翻译：

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一种新描述的灰百合（Lilium grayi）百合叶斑病（Pseudocercosporella inconspicua）的特征和症状

摘要 百合叶斑病是全球罕见的灰色百合 S. Wats.（美国阿巴拉契亚蓝岭南部特有种）的一种新出现的病害。该物种在它自然发生的三个州（北卡罗来纳州、田纳西州、弗吉尼亚州）被认为是受威胁或濒危物种。疾病导致地上组织的过早衰老和有性生殖的减少。孢子形态、科赫假设的完成和 DNA 序列数据显示百合叶斑病的病原体是 Pseudocercosporella inconspicua (G. Winter) U. Braun，一种百合特异性担子菌。诊断疾病的症状包括两性坏死病变，边缘呈棕褐色至绿色，周围环绕着白色至灰色粉状分生孢子团。在北卡罗来纳州/田纳西州罗恩山的实地研究中，在已知最大的人群中，表明基于形态学的视觉疾病诊断可以高度准确地预测 P. inconspicua 感染，并且 P. inconspicua 的高浓度分生孢子与受感染的 L. grayi 密切相关，但在未感染的 L. grayi 中基本上不存在或很少和其他物种。使用受感染的 L. grayi 叶组织作为接种物的田间接种试验导致疾病的传播和自然条件下过早衰老的诱导。