Epsilon Archive for Student Projects

Abstract

Alternaria solani is a major pathogen affecting potato (Solanum tuberosum), causing early
blight and significant yield annual losses globally. Due to the pathogen’s ability to develop
resistance to QoI fungicides and boscalid, a SDHI fungicide, concerns have arisen regarding
future fluopyram resistance. Fluopyram is a SDHI fungicide that inhibits fungal respiration
and is one of the active ingredients of a relatively new fungicide, Propulse. This study aimed
to assess the level of resistance of A. solani isolates to fluopyram and whether the isolates
studied showed signs of fungicide resistance 2 years after introduction of Propulse. Another
objective was to study the survival of the pathogen in soil during winter as this could
influence its epidemiology. The study was separated into three experiments: a germination
assay testing spore viability across fungicide concentration, the prevalence of A. solani on
treated or non-treated leaves and an evaluation of soil type on fungus survival. The
germination assay revealed a significant reduction in spore germination at high fluopyram
concentrations, although it did not completely inhibit spore viability. A. solani was detected
in all leaf samples, with fungicide-treated leaves unexpectedly containing higher levels of
Alternaria spp.. The presence of A. solani despite treatment, as seen on leaf samples and
germination assay, might indicate the possibility of lower sensitivity to the fungicide. The
results from the soil experiment aligned with current literature, showing enhanced survival of
A. solani in dry clay soils. These findings, although demonstrating fluopyram’s current
effectivity on the pathogen, hint towards future challenges. Increased temperatures tend to
lead to drier soils which could promote A. solani infections. Although, further research is
required to validate these observations.