不幸的是, 引起疾病的病原仍不明了.Unfortunately, the responsible pathogens were still unknown.感病的植物群体不暴露在它们的病原之下,这是相当普遍的.Nonexposure of susceptible plant populations to their pathogens is fairly common.在此情况下,需要特异性实验来确定病原.In such situati...

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“病原”的拼音为：bìng yuán...