Summary: Grapevine ( Vitis vinifera ) is a reservoir of fungal endophytes that may affect its growth, health status and grape production. Although there is growing interest in comparing fungal communities of mainly red grape varieties across various factors using only high‐throughput sequencing, the small‐scale mycobiome variations in geographically close vineyards need further examination. We aimed to characterize the fungal microbiome of the above‐ground tissues of V . vinifera cv. Furmint in different plant parts, seasons and sites using culture‐dependent and culture‐independent methods, and in planta fluorescent microscopic visualization techniques. Samples were collected from four sites of the Tokaj wine region in Mád and two reference sites in Eger, Hungary, across different seasons for 2 years. Fungal endophytes of young and mature leaves, flowers and grape bunches were collected at different phenological stages. Based on each technique, Aureobasidium pullulans , Cladosporium spp. and the complex species Alternaria alternata dominated the community at every site, season and plant organ. We found no significant difference among communities in distinct neighbouring vineyards, nor when compared with the distant reference sites. We can conclude that the different shoot parts of the Furmint grapevines harbour a common core group of fungal community in these regions.

Esca belongs to the group of grapevine trunk diseases - fungal diseases present worldwide in all wine-growing regions. Some aspects of the disease, like the development of external symptoms, have still not been completely discovered and are believed to be affected by several factors, including interactions within the vine microbiome. The examination of the occurrence of the yeast-like fungus Aureobasidium pullulans in the healthy wood of Esca-diseased grapevines via both isolation and qPCR measurements showed a positive correlation between its abundance and the severity of foliar symptoms, suggesting the contribution of this fungus to Esca pathogenesis via an indirect action. In vitro confrontation tests revealed antagonistic interaction between A. pullulans and the Esca pathogen Phaeomoniella chlamydospora. Mutual growth inhibition and the induction of asexual sporogenesis were observed for both fungi without cytotoxic effects. In planta confrontation tests revealed that A. pullulans in combination with P. chlamydospora can lead to severe foliar damage in a strain-dependent manner. This phenomenon could be explained by the altered metabolism of the Esca pathogen in the presence of A. pullulans, or by the cumulative/synergistic effects of the secreted polysaccharides and/or proteins of the two fungi. The present study shows the importance of microbial interactions in the development of plant diseases, highlighting that even a non-pathogenic microorganism can act as a disease-enhancer.

The best known Microdochium spp. are important pathogens of small-grain cereals and/or endophytes of diverse monocot hosts. This study is the first report of M. majus isolated from asymptomatic grapevine tissues. It was hypothesised that this M. majus strain, CBS 152328, was an endophyte and an antagonist of some fungal pathogens of grapevine. Microscopic examinations revealed that this strain was a necrotrophic mycoparasite of Botrytis cinerea. This was demonstrated in the confrontation zones of dual cultures of M. majus and B. cinerea, and also on the surface of co-inoculated grape leaf discs and germinated wheat grains. Pathogenicity tests indicated that M. majus can colonise both grape leaf discs and germinated wheat, but it only damaged wheat. When co-inoculated with B. cinerea onto grape leaf discs, the M. majus strain CBS 152328 suppressed its mycohost on grape tissues and prevented leaf necrosis caused by B. cinerea. In addition to the parasitism, M. majus also showed mild antibiosis against B. cinerea, as well as a defence elicitor effect on grape leaf discs. This work is the first report of the mycoparasitic behaviour of M. majus, in addition to its first isolation from a dicot host.

Various oils can efficiently control a wide range of pests and pathogens on plants. In this study, we tested the effectiveness solely applied paraffin oil (PFO) spraying against Erysiphe necator, the causal agent of grape powdery mildew (GPM). Its effects on gas exchange and yield at harvest were also investigated. Experiments were conducted in Eger between 2013 and 2014 with two cultivars (Kékfrankos and Chardonnay) showing differing susceptibility to GPM. Treatments with 2.2 and 3.3 v/v% PFO spraying inhibited GPM; however, this effect was influenced by the individual resilience of the variety and the infection pressure of the vintage. The PFO treatment caused decreased leaf gas exchange parameters compared to conventional treatment. The berry yield was also lower in PFO-treated parcels, although yield may be affected by numerous factors and requires further investigation. The mineral oils may have a phytotoxic effect on the grapevine through impairment of the photosynthetic performance, although this effect cannot be connected to a particular PFO concentration according to our research results. This negative effect of PFO highly depends on the ampelographic characteristics of the examined cultivars and vintage. In addition, the physical properties of the spraying agent may also play an important role.

Several members of the fungal genus Ilyonectria primarily infect plants through the roots and basal stem, causing ‘black foot’ diseases, predominantly in woody plants such as grapevine ( Vitis spp.) and walnut ( Juglans regia ). In 2021, four Ilyonectria liriodendri isolates were cultured from the necrotized roots of Diospyros virginiana plants in Eger, Hungary. The isolates were identified by sequencing the ITS, β-tubulin, and partial histone H3 genes. The obtained sequences were used for phylogenetic analysis through multiple sequence alignment and the construction of a Maximum Likelihood tree, which revealed that all four isolates belonged to the species Ilyonectria liriodendri . The macro- and micromorphological variations, as well as the differences in exoenzyme production of the isolates suggested that they represent a somewhat diverse set of the same taxon. To prove their association with the symptoms observed in the host plants, the roots of one-year-old D. virginiana plants were artificially infected with conidial suspensions of the isolates according to Koch’s postulates. After 90 days of incubation in a greenhouse, 16 out of 20 inoculated plants showed necrosis in the taproots, while mock-inoculated plants remained symptomless. Necroses developed in the roots of the infected plants, and the inoculated fungi were reisolated, reinforcing their pathogenicity against D. virginiana . To the best of our knowledge, this is the first report of I. liriodendri causing disease in persimmon.