Spongospora subterranea is a soilborne plasmodiophorid that causes powdery scab in potato. It also transmits potato mop-top virus (PMTV), which causes necrotic arcs (spraing) in potato tubers. Three field experiments were conducted in naturally S. subterranea-infested soil to investigate the effects of two chemicals, Omega 500F (fluazinam) and FOLI-R-PLUS RIDEZ (biological extract), on powdery scab, PMTV, and changes in S. subterranea inoculum with six different potato cultivars. The efficacy of soil treatment with these two chemicals on tuber lesions, root galling, and pathogen population was also assessed in greenhouse trials. The chemical treatments did not reduce powdery scab, root gall formation, or S. subterranea inoculum in the field or greenhouse trials. Postharvest S. subterranea soil inoculum in fields varied across farms and among potato cultivars but the pathogen population consistently increased by the end of the growing season. The evaluated russet cultivars were more tolerant to powdery scab than the yellow- or red-skinned cultivars but all were susceptible to PMTV. In the field, powdery scab indices and soil inoculum changes were positively correlated, while postharvest S. subterranea inoculum was positively correlated with root galling in both greenhouse trials. Powdery scab and PMTV occurred in noninoculated potting mix, indicating that peat-based potting mix is a source for both pathogens. These results demonstrate that chemical management methods currently used by farmers are ineffective, that S. subterranea and PMTV in potting mix can cause severe epidemics in greenhouses, and that potato cultivar choices impact inoculum increases in soil.

海绵状地下孢子虫是一种土壤传播的疟原虫，在马铃薯中引起粉状结ab。它还传播马铃薯拖布顶病毒（PMTV），该病毒在马铃薯块茎中引起坏死弧（散裂）。三个场实验在自然进行S. subterranea -infested土壤调查的两种化学物质的影响，欧米茄500F（氟啶胺）和佛力-R-PLUS RIDEZ（生物提取物），在粉状疮痂病，PMTV，和改变在S. subterranea有六个不同马铃薯品种的接种物。在温室试验中也评估了用这两种化学物质对块茎病害，根root和病原菌种群进行土壤处理的效果。化学处理并没有减少粉状结ab，根gall形成或地下链球菌。田间或温室试验中接种。田间收获后地下土壤接种物随农场和马铃薯品种的不同而变化，但病原菌种群在生长季节末期持续增加。经过评估的赤褐色品种比黄皮或红皮品种对粉sc的耐受性更高，但所有品种均易患PMTV。在田间，粉状结ab指数与土壤接种物变化呈正相关，而收获后的地下链球菌则呈正相关。在两个温室试验中，接种量与根gall病成正相关。未接种的盆栽混合物中出现粉状结ab和PMTV，表明基于泥炭的盆栽混合物是两种病原体的来源。这些结果表明，农民目前使用的化学管理方法无效，盆栽混合物中的地下链球菌和PMTV可能导致温室中的严重流行病，马铃薯品种的选择会影响土壤中接种物的增加。