Peach orchards in the northeast of Spain were severely affected in 2012 by a previously unreported disease in this area. The symptoms included early reddening, leaf curling, decline, abnormal fruits, and in some cases death of the peach trees. All the infected peach samples were positive for ‘ Candidatus Phytoplasma pyri’, but none were infected by the ‘ Ca . Phytoplasma prunorum’. In this work, potential vectors able to transmit ‘ Ca . Phytoplasma pyri’ from pear to peach and between peach trees were studied and their infective potential was analysed at different times of the year. Transmission trials of the phytoplasma with potential vectors to an artificial feeding medium for insects and to healthy peach trees were conducted. Additionally, isolated phytoplasmas were genetically characterized to determine which isolates were able to infect peach trees. Results showed that the only insect species captured inside peach plots that was a carrier of the ‘ Ca . Phytoplasma pyri’ phytoplasma was Cacopsylla pyri . Other insect species captured and known to be phytoplasma transmitters were present in very low numbers, and were not infected with ‘ Ca . Phytoplasma pyri’ phytoplasma. A total of 1928 individuals of C. pyri were captured in the peach orchards, of which around 49% were phytoplasma carriers. All the peach trees exposed to C. pyri in 2014, and 65% in 2015, were infected by ‘ Ca . Phytoplasma pyri’ 1 year after exposure, showing that this species is able to transmit the phytoplasma to peach. Molecular characterization showed that some genotypes are preferentially determined in peach.

Xylella fastidiosa (XF) is a Gram-negative bacterium responsible for severe plant diseases affecting a wide range of host plants, some of them important crops. Since 2017, only the pauca subspecies (ST80) have been identified in Ibiza. XF is naturally transmitted by xylem sap-feeding insects; among them, only Philaenus spumarius (PS) and Neophilaenus campestris Fallén (NC) have been reported as potential insect vectors for XF in Ibiza. This study aims to investigate the dissemination of XF and to propose effective control strategies. The crops and the surrounding vegetation were sampled for potential vectors. DNA from insects was extracted and amplified by three qPCR methods, allowing subspecies identification. The results confirmed the continuous presence of adults of PS and NC in Ibiza and Formentera from May to December with important populations. During the summer period, PS captures predominantly took place within the surrounding woody vegetation adjacent to the plots. The main host plant for PS was Pinus halepensis Miller in Ibiza and Juniperus phoenicea subsp. turbinata (Guss.) Nyman in Formentera. In Ibiza, off the total PS captures, 4.47% tested positive for XF. These results confirm that PS is the main vector of XF on these islands, both in terms of captures and the percentage of positive insects for XF. In Formentera, despite the presence of potential vectors and the proximity and contact with Ibiza, no XF-positive insects were found, confirming the absence of the bacterium on the island.

Spain is the second largest producer of artichoke (Cynara scolymus L.) in the world with 230,000 tons produced annually. The region of Catalonia, located in northeast Spain, has 3,500 ha dedicated to this crop. Low yield and degeneration anomalies are widespread problems in the Mediterranean area. The degeneration syndrome results in curled leaves and late development of capitulum. The association of this syndrome with different viruses such as Artichoke degeneration virus (ADV), Artichoke latent virus (ALV), Broad bean wilt virus (BBWV), Cucumber mosaic virus (CMV), and many others was not conclusive. Other studies indicated that this phenomenon could be related to a regression of the cultivar toward the species of origin, the wild cardoon (C. cardunculus L. var. sylvestris). The distribution of degenerated plants in the principal artichoke-growing areas of Catalonia together with the presence of plants with normal and degenerated tissues in the same plant suggested the presence of phytoplasmas. Samples from 30 symptomatic and 30 asymptomatic plants of cv. Blanca de Tudela were collected in February of 2006 from different areas of Catalonia and analyzed by PCR amplification of phytoplasma DNA. DNA for PCR analyses was prepared from leaf petioles and midribs according to the Ahrens and Seemüller procedure (1). Nested-PCR was carried out with rRNA primer pairs P1/P7 and fU5/rU3 (2,3). Alternatively, nested-PCR, with primers Tuf 1 f/r in the first step and Tuf AY f/r in the second, amplifying a DNA fragment of the elongation gene Tu of the phytoplasmas belonging to Aster yellows and stolbur groups was conducted (4). Results showed a high correlation between presence of symptoms and phytoplasma detection. Phytoplasmas were detected in 100% of the symptomatic plants (30 of 30) and only in one of the asymptomatic plants. The restriction fragment length profiles of Tuf AY amplicons with HpaII showed two different patterns, the most important belonging to the aster yellows (16SrI) group phytoplasma and the other to the stolbur (16SrXII) group phytoplasma. To our knowledge, this is the first time that phytoplasmas have been detected in artichoke and associated with degeneration of this crop. References: (1) U. Ahrens and E. Seemüller. Phytopathology 82:828, 1992. (2) S. Deng and C. Hiruki. J. Microbiol. Methods 14:53, 1991. (3) K. H. Lorenz et al. Phytopathology 85:771, 1995. (4) B. Schneider et al. Microbiology 143:3381, 1997.

Understanding the spread of Xylella fastidiosa (XF) in agroforestry systems is key to reducing its ecological and economic impact. In Minorca (Balearic Islands), the subspecies multiplex (ST81) was detected for the first time in 2017, mainly affecting wild olive (Olea europaea var. sylvestris), a key species in Mediterranean shrublands. This study analyzes XF dynamics and its insect vectors, Philaenus spumarius (PS) and Neophilaenus campestris (NC), over three years (2019–2021) in six agroecosystems. A total of 621 Auchenorrhyncha specimens were collected and analyzed by qPCR. XF was detected in 11.88% of PS but not in NC. PS was predominantly captured on herbaceous cover and Pistacia lentiscus and less often on wild olive and Rhamnus alaternus. Infection rates in PS peaked in summer and autumn, reaching over 50% in some months, especially on wild olives. XF was also confirmed in wild olive in all plots, with infection rates between 10% and 55%. No phytoplasmas were found. These results highlight the major role of PS in XF transmission in Minorca, with wild olive as a key reservoir. The findings stress the importance of vector behavior, host plants, and landscape structure in managing XF in Mediterranean agroforestry systems, indicating migration to woody hosts as a key factor.