Septoria melissae Desm., the most important pathogen of lemon balm (Melissa officinalis) occurs each year on plantations. The fungus may cause serious yield losses in the absence of proper plant protection. Breeding resistant or tolerant cultivars could play an important role in plant protection of medicinal plants. However, only a few descriptions of tolerant varieties of lemon balm are available. The goal of this work was to evaluate the susceptibility of three accessions of M. officinalis against the pathogen of Septoria leaf spot under field conditions at Budapest-Soroksár (Hungary) in 2017-2018. Differences in susceptibility of the accessions were observed in both years. The accession of M. officinalis subsp. altissima proved to be the least susceptible to Septoria infection. The frequency of the infected leaves was only 5.1 and 28.1% in 2017 and 2018, respectively. However, the cultivar M. officinalis subsp. officinalis 'Lorelei' turned out to be the most susceptible to the pathogen with an average infection level of 26.1 and 66.6%, 1.3-6.1 times higher than that of the other accessions in each year, respectively. Development of disease tolerant M. officinalis cultivars may be an effective tool in the plant protection of lemon balm.

Invasive species pose increasing threats, particularly in agriculture. Here we assess the open-field distribution, population density, and phenology of Tuta absoluta (Lepidoptera: Gelechiidae), an invasive pest rapidly expanding its range into open-field habitats in Hungary. Countrywide monitoring using sex pheromone traps was conducted at 23 sites in 2023, complemented with detailed seasonal monitoring at two locations. The results reveal a wide open-field distribution of the pest in Hungary, occurring at 21 of the 23 sampled sites. Population densities were significantly higher in highly urbanised areas, suggesting that warmer climatic conditions enhance colonisation and population growth. Continuous adult flight activity was recorded from May to December, indicating prolonged reproductive activity and overlapping generations. Based on the degree-day requirements (approx. 460 °C days per generation), five generations per year were expected and detected at two intensively sampled sites. These findings demonstrate a marked shift from the “greenhouse pest” status toward successful colonisation of open fields, supported by increased overwintering potential. The observed expansion and phenological changes indicate that the climatic conditions of temperate Hungary are increasingly suitable for the persistence of T. absoluta populations outdoors. This study underscores the growing agricultural risk posed by T. absoluta in temperate regions and highlights the importance of early detection and integrated pest management strategies for mitigating its impact.