Pathogenicity of Single and Combined Inoculations of Alternaria spp. on Potato

In Europe, early blight has become an increasingly severe disease in potato cultivation. We investigated the lesion sizes caused by infection with different Alternaria spp . predominantly from the UK in detached-leaf assays and whole-plant assays of different potato cultivars. The analysis reveals that whilst there is no significant interaction between the potato cultivars used and the Alternaria spp. tested, statistically significant differences were observed between the group means of small-spored vs. large-spored Alternaria spp. The small-spored species grouped together with no significant differences amongst them, whilst large-spored species were able to cause large expanding lesions in all tests, with Alternaria solani exhibiting the most extensive lesion growth. We also explored the effect of co-inoculation treatments of Alternaria spp., revealing no significant difference between the inoculation with Alternaria solani alone and co-inoculation with Alternaria solani and Alternaria alternata or Alternaria infectoria. The findings contribute to our understanding of the behaviour of Alternaria spp. and their impact on potato cultivars.