Csaba Németh

The invasive spotted wing Drosophila (SWD) represents new challenges for European and North American fruit producers. The aim of our study was to examine wine grape cultivar susceptibility to this pest and melanogaster-type Drosophila (MTD) by surveying drosophilid populations using field traps and conducting emergence tests. We assessed fly development from intact and artificially injured berries collected from four cultivars. Berries were incubated individually and in pooled samples to evaluate infestation patterns and potential larval interactions. Although grapes are generally considered less favorable hosts for SWD, the pest was consistently present across all vineyard plots. Infestation levels differed significantly among cultivars, with the Hungarian white cultivar Furmint being the most susceptible, while French-origin red cultivars Cabernet Franc and Cabernet Sauvignon, along with the other Hungarian cultivar Rózsakő, were less susceptible. Berry integrity played a crucial role: intact berries showed minimal infestation, whereas physical injuries led to a substantial and significant increase in infestation rates and fly emergence. In contrast to SWD-dominated trap catches and the nearly equal proportions of SWD and MTD observed in intact berries, injured berries were predominantly colonized by MTD. This dominance became even more pronounced in pooled samples, suggesting that larval competition in shared environments favors MTD over SWD. These findings underscore the importance of grape cultivar traits and berry condition in shaping Drosophila infestation dynamics. Further research into the chemical and ecological drivers of host selection and interspecific interactions is warranted to improve vineyard pest management strategies.

As the sensitivity of perennial crops to climate change becomes more pronounced, clonal selection, which is already very time-consuming for grapevine, may take even longer, while its importance is increasing. In the case of indigenous grapevine varieties, the purpose of clonal selection is twofold: to mitigate problems of cultivation and at the same time, to preserve the varietal character. The cultivation technique issue of ‘Kéknyelű’ is the low fertility (functionally female-flowered variety), and as for ‘Juhfark’ it is the significant susceptibility to grey rot. Based on daily meteorological data of 11 years, the years were classified into 3 groups and harvest data were analyzed within each group. Significant difference in yield was found between clone B.2. and the base ‘Kéknyelű’. Both clones of ‘Kéknyelű’ matured with significantly lower pH compared to the base variety. Given the acidic character of ‘Kéknyelű’ wine and the predicted rise in must °Brix and pH as a result of climate change, these differences may be useful in the future. Botrytis infection only showed statistically significant differences between year groups for ‘Juhfark’. It is intriguing that in most years, the rate of grey rot infection was lower in both clones compared to the base variety, especially in year groups 1 and 3 when the overall rate of Botrytis infection was quite low.

Due to climate change, the sugar content of grapes in Hungary has increased to such an extent that the high alcohol content alone can make wines disharmonious. In most vintages, this phenomenon is only a problem for early-ripening varieties. In order to prevent and treat this difficulty, we have carried out experiments in grape canopy management for four years with the aim of delaying ripening and thus reducing the sugar content of the grapes. The experiments were set up on an early (Pinot noir) and a late (Welshriesling) variety; two treatments (leaf removal—LR and short topping—ST) were applied and compared to untreated controls in the years 2019–2022. Our results showed that grape juice sugar yield was significantly reduced in all four years and for both cultivars, while the other measured parameters (yield, acidity, pH, and Botrytis infection) were only lightly affected.

In the case of indigenous grapevine varieties, the aim of clonal selection is twofold: to improve their technological cultivation problem while preserving the varietal character. As the sensitivity of perennial crops to climate change becomes more pronounced, clonal selection, which is already very time-consuming for perennial woody crops, may take even longer. In Badacsony, clonal selection breeding of the ‘Kéknyelű’ and ‘Juhfark’ varieties was started in the early 2000s. The problem mentioned above in cultivation technology is the poor fertility of ‘Kéknyelű’ (functionally female-flowered variety), while in the case of ‘Juhfark’ the high susceptibility to grey rot (Botrytis). Based on 11 years of data significant difference in yield between clone B.2. and the base variety was found. In this comparison the year clusters also gave different values, as in years belonging to cluster 1 the ’Kéknyelű’ yielded more than in another year. Both clones of ‘Kéknyelű’ matured with significantly lower pH compared to the base variety. ‘Kéknyelű' is renowned for the distinctive variety character of its wine, which is said to be acidic. Given the acidic nature of ‘Kéknyelű’ wine and the expected increase in must degrees and pH due to climate change, these distinctions may be beneficial in the future. Daily meteorological parameters were also recorded in the years under study, and different indexes were calculated for both of varieties for different phenological periods. The years were classified into 3 clusters and the harvest data were analyzed within each cluster. In the case of 'Kéknyelű' our results revealed significant differences in yield between vintage clusters for clone B.2. However, clone B.1 demonstrated distinct KMW and pH values. Both 'Kéknyelű’ clones have produced a substantially higher incidence of Botrytis infection in cluster 2 years than in cluster 3 years. Botrytis infection only showed statistically significant differences between year clusters for ‘Juhfark’. It is intriguing that in most years, the rotting rate was lower in both clones, especially in year clusters 1 and 3 when the overall rate of Botrytis infection was quite low. Our results highlighted the year-round sensitivity of the two varieties studied and the difficulties of clonal selection.

Grape production worldwide is increasingly threatened by grapevine trunk diseases (GTDs). No grapevine cultivar is known to be entirely resistant to GTDs, but susceptibility varies greatly. To quantify these differences, four Hungarian grape germplasm collections containing 305 different cultivars were surveyed to determine the ratios of GTDs based on symptom expression and the proportion of plant loss within all GTD symptoms. The cultivars of monophyletic Vitis vinifera L. origin were amongst the most sensitive ones, and their sensitivity was significantly (p < 0.01) higher than that of the interspecific (hybrid) cultivars assessed, which are defined by the presence of Vitis species other than V. vinifera (e.g., V. labrusca L., V. rupestris Scheele, and V. amurensis Rupr.) in their pedigree. We conclude that the ancestral diversity of grapes confers a higher degree of resilience against GTDs.

Due to climate change, the sugar content of grapes in Hungary has increased so the high alcohol content alone can make wines disharmonious. In most vintages, this phenomenon is only a problem for early-ripening varieties. In order to prevent and treat this difficulty, we have been carrying out experiments in grape canopy management for four years with the aim of delaying ripening and thus reducing the sugar content of the grapes. The experiments were set up on an early (Pinot noir) and a late (Welshriesling) variety; two treatments (leaf re-moval - LR and short topping - ST) were applied and compared to untreated control in the years 2019-2022. Our results showed that must sugar yield was significantly reduced in all four years and for both of cultivars, while the other measured parameters (yield, acidity, pH, Botrytis infection) were not or lightly affected.

Grape production worldwide is increasingly threatened by grapevine trunk diseases (GTDs). No grapevine cultivar is known to be entirely resistant to GTDs, but susceptibility varies greatly. To quantify these differences, four Hungarian grape germplasm collections containing 305 different cultivars were surveyed to determine the ratios of GTDs based on symptom expression and mortality rate. The cultivars of monophyletic Vitis vinifera L. origin were amongst the most sensitive ones, and their sensitivity was significantly (p<0.01) higher than that of the interspecific (hybrid) cultivars assessed, which are defined by the presence of Vitis species other than V. vinifera (e.g. V. labrusca L., V. rupestris Scheele, V. amurensis Rupr.) in their pedigree. We conclude that ancestral diversity of the grape confers higher degrees of resilience against GTDs.