Oregon State University, Department of Botany and Plant Pathology, Corvallis 97331, USA.
Phytopathology. 2010 Dec;100(12):1330-9. doi: 10.1094/PHYTO-03-10-0097.
The biological control agents Pseudomonas fluorescens A506 and Pantoea vagans C9-1 were evaluated individually and in combination for the suppression of fire blight of pear or apple in 10 field trials inoculated with the pathogen Erwinia amylovora. The formulation of pathogen inoculum applied to blossoms influenced establishment of the pathogen and the efficacy of biological control. Pantoea vagans C9-1 suppressed fire blight in all five trials in which the pathogen was applied as lyophilized cells but in none of the trials in which the pathogen was applied as freshly harvested cells. In contrast, Pseudomonas fluorescens A506 reduced disease significantly in only one trial. A mixture of the two strains also suppressed fire blight, but the magnitude of disease suppression over all field trials (averaging 32%) was less than that attained by C9-1 alone (42%). The two biological control agents did not antagonize one another on blossom surfaces, and application of the mixture of A506 and C9-1 to blossoms resulted in a greater proportion of flowers having detectable populations of at least one bacterial antagonist than the application of individual strains. Therefore, the mixture of A506 and C9-1 provided less disease control than expected based upon the epiphytic population sizes of the antagonists on blossom surfaces. We speculate that the biocontrol mixture was less effective than anticipated due to incompatibility between the mechanisms by which A506 and C9-1 suppress disease.
荧光假单胞菌 A506 和 Pantoea vagans C9-1 这两种生物防治剂分别在 10 个田间试验中，与病原菌欧文氏菌（Erwinia amylovora）一起进行接种，评估它们对梨或苹果火疫病的抑制效果。应用于花朵的病原菌接种剂的配方会影响病原菌的建立和生物防治的效果。Pantoea vagans C9-1 在病原菌以冻干细胞形式应用的所有 5 个试验中都抑制了火疫病，但在病原菌以新鲜收获的细胞形式应用的试验中都没有抑制。相比之下，荧光假单胞菌 A506 仅在一个试验中显著降低了疾病。两种菌株的混合物也抑制了火疫病，但在所有田间试验中的疾病抑制程度（平均为 32%）低于 C9-1 单独使用时的程度（42%）。这两种生物防治剂在花朵表面上不会相互拮抗，并且将 A506 和 C9-1 的混合物应用于花朵会导致有检测到至少一种细菌拮抗剂的花朵比例大于单独使用单个菌株的比例。因此，混合物 A506 和 C9-1 提供的疾病控制效果低于预期，这是基于拮抗剂在花朵表面的定殖种群大小。我们推测，由于 A506 和 C9-1 抑制疾病的机制之间不兼容，生物防治混合物的效果不如预期。
