Surveys on the occurrence of type A trichothecenes in wheat, and particularly for the T‐2 and HT‐2 toxins, and information on the biology and epidemiology of the causative Fusarium species (i.e. F. langsethiae, F. sporotrichioides) are scarce in Italy, as compared to the more common type B trichothecene, deoxynivalenol and its producers. This 4‐year monitoring of phytopathogenic Fusarium species on 183 seed lots of durum wheat shows wide distribution of F. langsethiae in Italy and the potential of several isolates of this fungus to produce high amounts of T‐2 and HT‐2 in wheat. Fusarium langsethiae was observed for approximately 48% of the analysed samples, with a maximum incidence for a single lot of 10.5%. Fusarium sporotrichioides was observed only in 2011, with an average incidence of 2% (range, 0–3%). A collection of F. langsethiae isolates representative of the main cultivation areas in Italy was established. These isolates showed great variability for their toxin production in vitro. Of 28 strains, all except one isolate can produce the T‐2 and HT‐2 toxins. HT‐2 was generally in greater amounts than T‐2, with an average concentration ratio for HT‐2 to T‐2 of 2.1 (range, 0.7–5.4). The artificial inoculation of wheat with three isolates of F. langsethiae produced no Fusarium head blight symptoms under field conditions. However, significantly higher incidence of F. langsethiae was seen on the kernels of inoculated plants, compared to the uninoculated controls.

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Pyrenochaeta lycopersici is the causal agent of corky root rot, which is a serious disease worldwide that attacks the roots of tomato. A total of 139 isolates were sampled from eight locations in Italy and Israel and assigned to two molecular types (type 1 and type 2) based on internal transcribed spacer (ITS) sequences. These isolates were genotyped using amplified fragment length polymorphisms (AFLPs) to decipher the population structure. Based on this population structure analysis, three groups of P. lycopersici were identified. One group correlated to ITS type 1, while the other two correlated to ITS type 2. AMOVA indicated high genetic divergence (F ST = 0Á40) between the Italian types 1 and 2. These data support the view that the two ITS types represent significant evolutionary entities, although there might be incomplete lineage sorting present. Some isolates of different ITS type were observed to have very similar multilocus AFLP profiles, and some genotypes were intermediate between the two ITS types. This suggests that parasexual hybridization between the two types has had a significant role in shaping the population structure of P. lycopersici. Finally, the average divergence among the populations within the ITS types was very high (F SC = 0Á710, P < 10 À5 ), probably due to strong genetic drift and founder effects combined with restricted migration.