Blackleg (stem canker) of crucifers is a globally important disease caused by multiple genetic subclades of the fungi Plenodomuslingam (syn.: Leptosphaeria maculans) and Plenodomus biglobosus (syn.: Leptosphaeria biglobosa). In our study, we monitored the geographical distribution of these two pathogen species from rapeseed growing areas in Hungary. Multiplex PCR identified 48.7% of the isolates as Plenodomus biglobosus, which indicates the non-recent introduction of the pathogen into Hungary. In addition, multi-locus analysis revealed low genetic diversity within the species, as all isolates were clustered to the Plenodomuslingam ‘brassicae’ and Plenodomus biglobosus ‘brassicae’ subclades. The low genetic diversity of a population generally means reduced adaptation potential, which is essential information in breeding and in developing more effective management strategies.

‘Candidatus Phytoplasma prunorum’ is causing ever increasing economic losses through the decline of apricot trees in European countries, e.g., Hungary. In this study, the pathogen was identified from plant tissues and insects by nested-PCR. The insect species were identified via morphology and molecular methods. The incidence of the pathogen was 29.6% in randomly selected apricot trees. Most of the infected trees with symptoms died within a year. These results show that phytoplasma is significantly present and causes damage in the investigated plantations. The only known insect vector of this phytoplasma is the plum psyllid, Cacopsylla pruni, which was regularly encountered in the sampled apricot orchards and in their surroundings. In a two-year study, several adults among the sampled specimens were observed to be infected by the pathogen. This observation further confirms the role of the plum psyllid in vectoring the phytoplasma. All the sampled plum psyllid adults belonged to the ‘B’ biotype. Besides C. pruni, Cacopsylla crataegi was abundant in the samples. Several adults of the latter species were also infected by the pathogen ‘Ca. Phytoplasma prunorum’. The rates of occurrence of this phytoplasma in male and female adults of the two psyllid species appeared to be similar. The examined C. crataegi individuals showed genetic differences from each other and from specimens included in a previous investigation.

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