The significance of nematodes for disease development caused by other soil-borne pathogens has been demonstrated in many crops throughout the world and specifically prevalent are interactions between plant-parasitic nematodes and species of plant pathogenic fungi. Here, the interaction between the fungus Rhizoctonia solani (AG2) and the migratory endoparasitic root-lesion nematode Pratylenchus penetrans was investigated on potato. The hypotheses were that the combination of R. solani and P. penetrans would result in more severe canker lesions, reduced quality of the tubers and lower tuber yield, and we also expected higher nematode levels to render more nematode damage. To test this, potato plants were grown in pots in two replicate experiments and the presence and/or abundance of the two pathogens were controlled. The first three hypotheses were rejected as (1) the tuber yield decreased when the fungus and nematode occurred together but not more than the sum of their separate effects, i.e. additive, (2) there was no effect of presence of nematodes on the incidence of stem canker, and (3) the quality of tubers was actually partly improved as the presence of the nematodes reduced the likelihood of elephant hide on the tubers in one of the experiments. As expected, there were more visible nematode damages with addition of more nematodes, but beyond that the different nematode levels rendered in most cases similar responses. To have knowledge about interactions between pathogens, as the one showed here, is essential for disease control through appropriate management methods.

线虫对由其他土壤传播的病原体引起的疾病发展的重要性已在世界各地的许多农作物中得到证实，特别是植物寄生线虫与植物病原真菌物种之间的相互作用尤为普遍。在这里，在马铃薯上研究了真菌Rhizoctonia solani（AG2）和迁移性内寄生根病线虫Pratylenchus penetrans之间的相互作用。假设是R. solani和P. penetrans的组合会导致更严重的溃疡病，块茎质量下降和块茎产量降低，我们还预期更高的线虫水平会导致更多的线虫危害。为了对此进行测试，在两个重复实验中使马铃薯植物在盆中生长，并控制两种病原体的存在和/或丰度。前三个假设被拒绝，原因是（1）当真菌和线虫同时出现时，块茎产量下降，但不超过其单独作用的总和，即加性；（2）线虫的存在对线虫病的发生没有影响。 （3）在其中一项实验中，由于线虫的存在降低了块茎上大象皮的可能性，块茎的质量实际上得到了部分改善。不出所料，增加了更多的线虫，可见线虫受到的损害更大，但除此之外，在大多数情况下，不同的线虫水平可提供相似的响应。如此处所示，了解病原体之间的相互作用对于通过适当的管理方法控制疾病至关重要。