Abstract Xanthomonas gardneri is the common causal agent of bacterial spot affecting field tomatoes in Ontario, Canada but spread during seedling transportation and transplanting is poorly understood. Spread during transportation and irrigation was determined by placing symptomatic seedlings at the top of a simulated plug trailer with healthy seedlings 30.5, 61.0, 91.5, and 122 cm below to assess pathogen movement with different irrigation treatments. The incidence of seedlings with symptoms 14 days after irrigation in the top to bottom (3.9%) and bottom to top (5.4%) treatments was greater than the dip treatment (0.4%). Symptoms were found at all distances below the inoculation point. A second set of experiments looked at spread in a transplanter by placing wet or dry symptomatic seedlings through the transplanter prior to healthy seedlings. Epiphytic X. gardneri was found on healthy seedlings from all diseased treatments 14 days after treatment, indicating transmission of X. gardneri during transplanting. A third set of experiments assessed the impact of transplanter transmission in the field by monitoring symptom appearance in initially healthy seedlings planted in rows with either machine-transplanted diseased plants or hand-planted diseased plants. There was no difference in the time to symptom appearance, except for one plant position which was not in the direction of transplanting. Thus, factors other than contaminated transplanters may be more important in X. gardneri transmission under field conditions. Best management practices for bacterial spot in field tomatoes should consider irrigation practices in plug trailers, while the contribution of contaminated transplanters to epidemics is likely limited.

中文翻译：

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加德氏黄单胞菌在运输和移栽过程中对番茄幼苗的传播

摘要 Xanthomonas gardneri 是加拿大安大略省田间番茄细菌性斑点病的常见病原体，但在幼苗运输和移栽过程中传播的情况知之甚少。运输和灌溉过程中的传播是通过将有症状的幼苗放置在模拟插塞拖车的顶部，健康幼苗低于 30.5、61.0、91.5 和 122 厘米，以评估不同灌溉处理下的病原体移动。自上而下（3.9%）和自下而上（5.4%）处理灌溉后14天出现症状的幼苗发生率高于浸渍处理（0.4%）。在接种点以下的所有距离处都发现了症状。第二组实验通过在健康幼苗之前通过移栽机放置湿或干的有症状的幼苗来观察在移栽机中的传播。处理后 14 天，在所有患病处理的健康幼苗上都发现了附生 X. gardneri，表明在移栽过程中传播了 X. gardneri。第三组实验通过监测与机器移植的病株或手工种植的病株成行种植的最初健康幼苗的症状外观来评估移栽机在田间传播的影响。出现症状的时间没有差异，除了一个植物位置不在移栽方向上。因此，在田间条件下，受污染的移栽机以外的因素可能对加德氏线虫传播更为重要。田间番茄细菌斑病的最佳管理实践应考虑插拔式拖车的灌溉实践，