The present study reports the first data on the occurrence of the mosaic leafhopper, Orientus ishidae (Matsumura) (Hemiptera Cicadellidae), in Hungary. The species is of eastern Palaearctic origin ...and a few years after its first detection in the western Palaearctic it has been reported from several European countries. Recently the phytoplasma of Flavescence doree has been identified from O. ishidae individuals collected in Italy and Slovenia. Due to the fast spread and possible economic importance of the species, attention needs to be called to monitoring of this possible pest of grapevines.
The course of 'flavescence dorée' (FD) and 'bois noir' (BN) diseases can result in either recovery or death of affected grapevines. When farmers observe symptomatic grapevines, they must choose ...whether to replace or maintain the plants. To establish whether there is an advantage in replacing symptomatic grapevines, data were collected on the costs of replacing them (removing the diseased plants and planting new grapevines, with resultant yield loss during the rearing period) and growing them on (yield losses in symptomatic grapevines over the following years). To calculate the cost of maintaining FD-infected plants, the possibility was also considered that symptomatic grapevines may be sources of phytoplasmas for the vector Scaphoideus titanus Ball. symptomatic course of BN was observed in 'Chardonnay', and of FD in 'Chardonnay', 'Merlot' and 'Perera' grape cultivars. The costs of replacement decreased with the increase in the productive lifetime of the vineyards. The cost of maintenance was greatly influenced by the course of the diseases, and in the case of FD, also by the risk of new infections due to the fact that S. titanus acquires phytoplasmas from infected grapevines. The replacement of plants affected by BN is not profitable when recovery is the most frequent course of the disease, particularly when it is considered that replantings can, in turn, become infected. The replacement of plants affected by FD is not profitable for cultivars with a recovery near to 100% ('Merlot'), whereas it is necessary for cultivars where the course of the disease is frequently lethal ('Perera'). For cultivars with intermediate sensitivity, the decision varies in relation to agronomic / economic factors and to the risk of new infections ('Chardonnay'). For FD, both replacement and maintenance strategies need to be associated with S. titanus control inside and outside the vineyards. In the case of maintenance the infected plants can be sources of phytoplasmas, and in the case of replacement, the vector can also inoculate the new grapevines.
Grapevine yellows (GY) are diseases of Vitis vinifera caused by phytoplasmas. On the basis of DNA analysis, it is possible to distinguish different groups and subgroups among grapevine phytoplasmas. ...Flavescence doree (FD), the most serious problem in European vineyards, is caused by a phytoplasma which belongs to the elm yellows group (EY or 16SrV). Differences between 7 phytoplasma isolates in this group, found until now in French, Italian and German grapevines, and 4 phytoplasmas in the same group, isolated mainly from elm and alder in Europe and America, were investigated. These 11 EY-group isolates plus 3 non-EY phytoplasmas, were compared by PCR-RFLP analyses of two different DNA fragments using 8 restriction enzymes. Two French and two Italian grapevine isolates, classified as FD, appeared to be closely related and were also closer to an Italian alder phytoplasma. One French and one Italian FD isolate always showed the same restriction pattern. On the opposite, the three German grapevine isolates related to alder phytoplasmas in Germany appeared to be closer to the two elm phytoplasmas from America and Europe.
Following a request from the European Commission, the EFSA Panel on Plant Health (PLH) reviewed Italian technical guidelines and the ANSES (Agence nationale de sécurité sanitaire de l'alimentation, ...de l'environnement et du travail) opinion on the use of hot water treatment (HWT) on Vitis sp. planting material, assessing its efficacy in the elimination of the xylem‐invading bacterial pathogen, Xylella fastidiosa. HWT is a robust and reliable technique used to destroy life stages of pests (insects, nematodes) and to inactivate pathogens (phytoplasma, bacteria, fungi) in dormant plant propagation materials (grapevine and other crops). An effective HWT sanitizes the planting material without affecting plant survival and development. For grapevine, HWT to eliminate the Grapevine flavescence dorée phytoplasma (FD) from planting materials is among the special requirements for the introduction and movement of Vitis sp. to protected zones in the EU. The conditions of 50°C for 45 min, prescribed and recommended to sanitize grapevine planting material against FD, are considered by the Panel to be also effective against X. fastidiosa and its subspecies. Despite uncertainties on variable thermotolerances of the bacteria, a HWT treatment of 50°C for 45 minutes can effectively account for different thermotolerances. It should be noted that the quality of the HWT is subject to the proper application of the operating procedures to guarantee vigorous growth and pathogen freedom of planting material.
Scaphoideus titanus Ball, the main vector of Flavescence dorée phytoplasma, was monitored in Slovakia during 2013 and 2014. The species was present in the vineyards of eastern Slovakia but it was ...rarely found in the south of central part of the country. It was also found at many locations of western Slovakia but not in the southeast of western Slovakia. Higher abundance of S. titanus was detected in the vineyards with biological control. Varietal preference of the leafhopper was not confirmed. The first nymphs were found on June 5 and the last nymphs on July 17, adults occurred from the end of June to the end of September. There is one generation of S. titanus per year in Slovakia.
The appearance of the Flavescence Dorée phytoplasma and the possibility of its rapid spread by its vector, the American Grapevine Leafhopper (Scaphoideus titanus Ball) (AGVL), represent a serious ...threat to viticulture production in Slovenia and elsewhere in Europe. Insecticide treatment represents one of major means of reducing the abundance of AGVL in wine-growing areas. In the period from 2010 to 2011, five insecticides against AGVL were tested, and the efficacy of the substances was calculated according to the number of nymphs (at 2, 7, 14 and 21 d after application), which were counted on the grapevine leaves. In both years, the highest cumulative efficacy (96–97% or 0.01 nymphs/leaf) was confirmed for thiamethoxam, whereas chlorpyrifos-methyl showed a very high cumulative efficacy (87–89% or 0.01–0.02 nymphs/leaf). In 2010, indoxacarb exhibited only a 43% (0.09 nymphs/leaf) cumulative efficacy; however, its substitute in 2011, chlorpyrifos, was more effective (73% or 0.05 nymphs/leaf). A single application of pyrethrin demonstrated only 45–61% (0.05–0.09 nymphs/leaf) efficacy. Based on the results of our research, we recommend the use of thiamethoxam and chlorpyrifos-methyl against AGVL.
Phytoplasmas are cell‐wall less, uncultivable bacteria, belonging to the class Mollicutes. They parasitise both plant hosts and insect vectors, but knowledge of their biological and molecular ...properties is limited. In particular, analyses of 16S rDNA nucleotide sequences revealed that 16SrV group phytoplasma strains identified in grapevine plants are closely related, but associated with distinct ecologies. In this work, we investigated the evolutionary relationships of eight representative 16SrV phytoplasma strains by sequencing 15 ribosomal protein (rp) genes positioned within the S10‐spc operon. Phylogenetic analyses of concatenated nucleotide and amino acid sequences underscored that 16SrV phytoplasma strains infecting grapevine clustered together in a distinct clade, supporting the hypothesis that they have a probable common origin. Furthermore, sequence typing revealed the presence of single nucleotide polymorphisms distinguishing the analysed 16SrV phytoplasma strains. Moreover, rp gene nucleotide sequences could help the description and the accurate definition of ‘Candidatus’ species within the 16SrV group.
Verify the presence and the molecular identity of phytoplasmas in Northern and Central Italy vineyards where yellows diseases are widespread. Phytoplasma presence and identity were determined by ...PCR/RFLP analyses on 16S ribosomal gene testing 1424 symptomatic samples. The 65% of samples resulted phytoplasma infected; in particular 256 samples were found positive to phytoplasmas belonging to group 16SrV (mainly Flavescence dorée associated), and the remaining 37% was infected by phytoplasmas belonging to ribosomal subgroup 16SrXII-A (Stolbur or Bois Noir associated). 16SrV ribosomal group representative strains were further typed for variability in SecY and rpS3 genes. The results showed the presence of phytoplasmas belonging to 16SrV-C, 16SrV-D and to a lesser extent, 16SrV-A subgroup. Possible relationships between genetic polymorphisms of phytoplasma strains belonging to subgroup 16SrV-C and their geographic distribution and/or epidemic situations were detected. Bois Noir and Flavescence dorée phytoplasmas are present in significant percentages in the areas under investigation. Molecular tools allowed to identify phytoplasma-infected plants and the genes employed as polymorphism markers resulted useful in distinguishing and monitoring the spreading of the diseases associated with diverse phytoplasmas belonging to 16SrV subgroup in vineyards.
Grapevine is one of the most important crops cultivated across Europe. Climate factors and diseases constantly threaten its production. Recently, Flavescence dorée (FD), an incurable grapevine ...disease with the obligation to uproot each infected plant, has been widely spread in Europe. The symptoms of FD are visually expressed in the late summer. Currently, the adopted procedure consists in scouting for infected plants by trained experts, which is time-consuming and not frequent enough. As stress development causes subtle spectral changes before any visible symptoms appear, during the summer of 2022, hyperspectral and multispectral images were acquired in the two vineyards near Riva del Garda, Trentino, Italy. A classification accuracy between 90.2 % and 96.9 % in distinguishing between infected and healthy plants was obtained from the hyperspectral data. These findings justify further efforts to use an in-house developed, affordable multispectral camera, significantly reducing equipment cost and procedure complexity while mapping the relevant spectral channels.
Scaphoideus titanus is threatening the grapevine industry in Europe as vector of "flavescence doree" (FD) quarantine disease. It was recently identified in countries neighbouring Hungary, however S. ...titanus and FD were not recorded during the Auchenorrhyncha fauna monitoring performed in several Hungarian vineyards between 1997 and 2005. In 2006 new sites near the Hungarian borders, in 9 counties, were involved in the surveys. S. titanus was found in Bacs-Kiskun, Somogy, and Zala counties: this is the first report of this insect in Hungary. The highest populations were recorded in abandoned vineyards near the Serbian border. Analyses to verify phytoplasma presence and identity were carried out in symptomatic grapevines and leafhoppers collected in these places, only the "bois noir" phytoplasmas were identified.
PDF
