ABSTRACT Potato common scab (CS) is caused by several saprophytic bacteria of the genus Streptomyces, including Streptomyces scabies. Various methods have been investigated to control CS, but their efficiency is usually low. Biopesticide formulations, including bacteria from the Bacillus spp., are increasingly used to control soil pathogens. Two Bacillus-based products, Double Nickel 55TM and Microflora PROTM, and the phosphite-based fungicide PhostrolTM, alone or in combination, were examined to determine their effects on CS development on tubers of the potato cultivars Red Pontiac, Prospect, Green Mountain, and Goldrush. CS disease incidence and severity were assessed using 4 parameters: percentage of tuber area covered by CS, necrotic areas, the number of deep pits and of shallow pits. The effects of treatments on tuber periderm morphology were assessed by determining the number of suberised cell layers and the thickness of suberised cell layers. Cultivar Goldrush performed much better than the other three cultivars, in all parameters scored. Among the six treatments, only Double Nickel 55TM + PhostrolTM reduced CS more consistently. Suberised cell size, shape, arrangement, number of layers, and phellem thickness, were found to vary largely across cultivars. A thicker phellem, but not the number of cells in the phellem, was found to be associated with improved resistance to CS. Treatments had limited effect on the number of layers of suberised cells and phellem thickness and these effects seemed to be cultivar specific. Overall, Double Nickel 55TM and Microflora PROTM were found to augment the number of suberised cell layers.

中文翻译：

---

评估生物农药和亚磷酸盐对马铃薯常见痂病发展的抑制作用

摘要 马铃薯常见疮痂病 (CS) 是由链霉菌属的几种腐生细菌引起的，包括链霉菌疥疮。已经研究了各种方法来控制 CS，但它们的效率通常很低。生物农药制剂，包括来自芽孢杆菌属的细菌，越来越多地用于控制土壤病原体。研究了两种基于芽孢杆菌的产品，Double Nickel 55TM 和 Microflora PROTM，以及基于亚磷酸盐的杀菌剂 PhostrolTM，单独或组合使用，以确定它们对马铃薯栽培品种 Red Pontiac、Prospect、Green Mountain 和淘金热。使用 4 个参数评估 CS 疾病的发生率和严重程度：CS 覆盖的块茎面积百分比、坏死区域、深坑和浅坑的数量。通过确定枯萎细胞层的数量和枯萎细胞层的厚度来评估处理对块茎周皮形态的影响。在所有参数评分中，Goldrush 品种的表现比其他三个品种要好得多。在六种处理中，只有双镍 55TM + PhostrolTM 更一致地降低 CS。发现栓化细胞的大小、形状、排列、层数和木栓厚度在不同品种之间差异很大。发现较厚的木栓与提高对 CS 的抗性有关，但与木栓中的细胞数量无关。处理对木栓化细胞层数和木栓厚度的影响有限，这些影响似乎是栽培品种特异性的。总体而言，发现双镍 55TM 和 Microflora PROTM 增加了木栓化细胞层的数量。