Host status and damage potential of <em>Meloidogyne</em> species in mint and parsley production

Abstract

Peppermint and parsley are widely cultivated medicinal and aromatic plants, and like many other crops, they are vulnerable to infections caused by plant-parasitic nematodes of the genus <em>Meloidogyne</em>. Host status of commonly cultivated varieties and the damage potential of <em>Meloidogyne</em> species from temperate climates in production of these plants remain unknown. <em>Meloidogyne</em> species are also known to interact synergistically with other soil pathogens, contributing to disease complexes. Mint is known to be affected by soil-borne pathogens such as <em>Verticilium dahliae</em>, which causes severe <em>Verticillium</em> wilt disease. It has been reported that certain plant-parasitic nematodes, such as <em>Pratylenchus</em> can interact synergistically with <em>V. dahliae</em> on mint. However, it remains unknown whether <em>Meloidogyne</em> species or species from other plant-parasitic nematode groups are also capable of such interactions. In the present work, peppermint and parsley responses were investigated against <em>Meloidogyne</em> species from temperate climates. In addition, we assessed the potential involvement of <em>M. hapla</em> and <em>Paratylenchus projectus</em> in synergistic interactions with <em>V. dahliae</em> on peppermint. By examining these aspects through three separate studies, we addressed previously underexplored responses of mint and parsley varieties cultivated in Germany to <em>Meloidogyne</em> infection, highlighting the importance of this knowledge for developing effective and sustainable nematode management. <br/> The impact of <em>Meloidogyne</em> species was determined under controlled conditions in the greenhouse. Results showed that the selected mint and parsley varieties are good hosts for <em>Meloidogyne</em> species. However, host status varied depending on the nematode species and plant variety. All studied varieties were susceptible to <em>M. hapla</em>, but showed tolerance to its infection, as no growth reduction was observed. However, at the highest density, <em>M. hapla</em> reduced the essential oil content in peppermint, indicating that tolerance applies only to plant growth but not to plant secondary metabolites. Furthermore, the identification of peppermint 'Multimentha' as a non-host to <em>M. chitwoodi</em> and <em>M. fallax</em> offers valuable control options by crop rotation targeting these nematodes. Additionally, <em>M. hapla</em> and <em>P. projectus</em> exhibited synergistic interactions with <em>V. dahliae</em> in peppermint, increasing <em>Verticillium</em> wilt severity. These findings highlight the critical need for integrated nematode management in peppermint cultivation affected by <em>Verticillium</em> wilt.