Diversity and Pathogenicity of Species Associated with Stalk and Crown Rot in Maize in Northern Italy.

The genus includes several agronomically important and toxin-producing species that are distributed worldwide and can cause a wide range of diseases. Crown and stalk rot and grain infections are among the most severe symptoms that spp. can cause in maize. Disease development usually occurs during germination, but it may also affect the later phases of plant growth. The purpose of this study was to investigate the diversity and pathogenicity of 41 isolates recovered from symptomatic seedlings collected in Northern Italy and seeds of five different geographical origins in 2019 and 2020. The pathogenicity was tested and confirmed in 23 isolates causing rotting in maize seedlings, with disease indexes from 20% to 90%. A multilocus phylogeny analysis based on four genomic loci (, , and ) was performed on 23 representative isolates. Representative isolates were identified as species belonging to three species complexes (SC), including and in the SC. was identified in the SC, and three different lineages were found in the SC. This study reports and two lineages of the SC as maize pathogens for the first time in Italy.