Nitzan Nadav, Cummings Tom F, Johnson Dennis A
Department of Plant Pathology, Washington State University, Pullman 646430.
Plant Dis. 2008 Nov;92(11):1497-1502. doi: 10.1094/PDIS-92-11-1497.
Inoculum of Colletotrichum coccodes, the cause of potato black dot, is soil- or tuberborne. Understanding the disease potential of sources of inocula is crucial for developing disease management strategies and resistance screening techniques. Two hypotheses were tested in this study: (i) soilborne inoculum causes more disease than tuberborne inoculum and (ii) black dot severity is related to the concentration of soilborne inoculum. Trials were conducted in the greenhouse with standardized inoculum. Plants grown in infested soil had more sclerotia on roots than plants grown from infected tubers in three of four trials. In general, plants grown in infested soil produced fewer tubers and lower yields than the noninoculated plants. Plants grown from infected tubers produced similar numbers of tubers as the noninoculated plants in all trials, and had reduced yields in one of the four trials. Increasing concentrations of soilborne inoculum had a nonlinear association with disease development. Foliar symptoms, sclerotial density on roots, and sclerotial development on stems did not increase when soil inoculum exceeded 0.5 or 1.7 g/liters of soil. In this study, soilborne inoculum caused more disease than tuberborne inoculum and disease severity remained constant above a threshold of soilborne inoculum.
引起马铃薯黑点病的围小丛壳菌接种体可通过土壤或块茎传播。了解接种体来源的致病潜力对于制定病害管理策略和抗性筛选技术至关重要。本研究检验了两个假设：（i）土壤传播的接种体比块茎传播的接种体导致更多病害；（ii）黑点病严重程度与土壤传播接种体的浓度有关。在温室中使用标准化接种体进行试验。在四项试验中的三项试验中，生长在受侵染土壤中的植株根系上的菌核比由感染块茎生长而来的植株更多。总体而言，生长在受侵染土壤中的植株比未接种的植株产生的块茎更少，产量更低。在所有试验中，由感染块茎生长而来的植株产生的块茎数量与未接种的植株相似，并且在四项试验中的一项试验中产量降低。土壤传播接种体浓度的增加与病害发展呈非线性关系。当土壤接种体超过0.5或1.7克/升土壤时，叶片症状、根系上的菌核密度和茎上的菌核发育并未增加。在本研究中，土壤传播的接种体比块茎传播的接种体导致更多病害，并且在土壤传播接种体的阈值以上病害严重程度保持不变。
