Latent mosaic is a widely distributed disease of peach caused by peach latent mosaic viroid (PLMVd). Some strains induce mosaic symptoms on leaves, delay in leaf emergence, flowering and maturity, calico and malformation of fruits with cracked sutures and enlarged pits, bud necrosis and, in more severe cases, early decline of the trees. To prevent the use of infected propagating material, international certification schemes provide for the absence of PLMVd from peach mother plants. Until a few years ago, detection of PLMVd was mainly based on cross‐protection tests on GF305 peach seedlings. Recently, improved knowledge of the PLMVd genome and optimization of molecular techniques applied to the diagnosis of plant pathogens have stimulated studies aimed at setting up diagnostic methods that are sensitive, reliable and less time‐consuming. A comparative trial among different Italian institutions has been set up to compare the sensitivity, specificity and reproducibility of the currently available diagnostic techniques that are routinely applied for the detection of PLMVd in peach germplasm. In this paper, we compare the results obtained in the diagnosis of PLMVd performed with biological indicators and molecular techniques (‘spot‐blot’ and ‘tissue‐blot’ hybridization using a non‐radioactive probe and reverse transcriptase‐polymerase chain reaction) starting from different organs (leaves, buds and bark) collected from infected and healthy peach plants and using two total nucleic acid extraction methods. On the basis of the results obtained, we suggest that a tissue‐blot hybridization assay using a PLMVd cRNA digoxigenin‐labelled probe and starting from bud tissue is a reliable diagnostic method for inclusion in quarantine or certification protocols that require the absence of PLMVd from propagating material of peach.

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Olive trees are infected and damaged by Botryosphaeriaceae fungi in various countries. The botryosphaeriaceous fungus Neofusicoccum mediterraneum is highly aggressive and is a major concern for olive groves in Spain and California (USA), where it causes ‘branch and twig dieback’ characterized by wood discoloration, bark canker, and canopy blight. During surveys of olive groves in Apulia (southern Italy), we noticed that—in some areas—trees were heavily affected by severe branch and twig dieback. In addition, chlorosis and the appearance of red-bronze patches on the leaf preceded the wilting of the foliage, with necrotic leaves persisting on the twigs. Given the severity of the manifestation in zones also subject to olive quick decline syndrome (OQDS) caused by Xylella fastidiosa subsp. pauca, we investigated the etiology and provide indications for differentiating the symptoms from OQDS. Isolation from diseased wood samples revealed a mycete, which was morphologically and molecularly identified as N. mediterraneum. The pathogenicity tests clearly showed that this fungus is able to cause the natural symptoms. Therefore, also considering the low number of tested samples, N. mediterraneum is a potential causal agent of the observed disease. Specifically, inoculation of the twigs caused complete wilting in two to three weeks, while inoculation at the base of the stem caused severe girdling wedge-shaped cankers. The growth rate of the fungus in in vitro tests was progressively higher from 10 to 30 °C, failing to grow at higher temperatures, but keeping its viability even after prolonged exposure at 50 °C. The capacity of the isolate to produce catenulate chlamydospores, which is novel for the species, highlights the possibility of a new morphological strain within N. mediterraneum. Further investigations are ongoing to verify whether additional fungal species are involved in this symptomatology.