A serious outbreak of flavescence dorée (FD) was reported in Piemonte, northwestern Italy, in 1998, and since then, the disease has compromised the economy of this traditional wine-growing area, even following the application of compulsory insecticide treatments to control Scaphoideus titanus, the vector of the causal phytoplasma. Affected vines show severe symptoms, varying according to the cultivar, and are rogued to reduce disease spread. Following winter and pruning, a previously affected vine may appear symptomless and free of phytoplasmas in its aerial as well as its root system, even by nested-polymerase chain reaction assays. Such plants are considered to be "recovered". Since 1998 homogenous data on the incidence of newly infected, healthy, or recovered plants productivity, presence of vectors, and treatment schedules have been collected in seven severely affected vineyards of southern Piemonte for 5 years (1999 to 2003). Infectivity and recovery rates were also calculated each year. From 1999 to 2003, the average number of healthy plants decreased and the numbers of recovered plants and those with symptoms increased. Productivity of recovered vines, although lower than that of healthy ones, was always higher than that of vines with symptoms and was not influenced by the time elapsed from date of recovery. The relationships between the ln-transformed number of vectors trapped in the vineyards the previous year and the infection and the recovery rates were fitted by an exponential (R(2) = 0.95) and an asymptotic (R(2) = 0.93) model, respectively.
In autumn 1996, adult Persian walnut {Juglans regia L.) trees cultivated in Piedmont (north-west of Italy) showed irregularly shaped cankers along the bark. When the phelloderm was removed, extensive necrosis of the tissues below was observed. A watery, dark-coloured exudale was also frequently observed. Symptoms were present on approximately 10% of 600 trees. Biochemical, nutritional and pathogenicity tests as well as fatty acids analysis of the isolates and type-strain, indicated that Erwinia nigrifluens was the causal agent of the disease. This is the first report of this pathogen in Italy.
At the begititiing of spring 1996, raised, brown areas along the bark of trunk and twigs were observed on
Kiwifruit early decline syndrome is a widespread disorder that affects worldwide kiwifruit orchards. During the last few years, the seriousness and diffusion of this disorder worsened; as a consequence, in several rural areas the economic sustainability of farms was seriously affected. The early symptoms involve leaves (epinasty, chlorosis, desiccation, and abscission), fruits (decrease of number, size, and sugar content), and roots (anomalous morphology and anatomy). After symptoms occurrence, in a short time plants collapse and die: frequently this happens in the same or in the following year. Even though several phytopathological or agronomical studies have been carried out, a clear and univocal explanation of the causes and the possible remedies are yet to be understood. A field trial was carried out in an experimental kiwifruit orchard, in which several soil management practices (ridging, amendment with compost, bioinoculation with selected rhizospheric microorganisms) were tested to evaluate their effect on early decline symptoms occurrence. The analysis of plant growth parameters, root morphology and anatomy, and symptoms onset were related to environmental data (air and soil temperature, soil water tension). The results pointed to a possible role and interaction between agronomic soil management and climatic conditions as the triggering factors of kiwifruit early decline syndrome.
A sudden apoplexy of young nectarine trees was observed during early autumn 1995 in Piedmont (northern Italy). At collar level, extensive wet necrosis of the tissues beneath the bark was observed. When the infection girdled the trunk, the tree died. LOPAT tests, fluorescence on single‐carbon sources and comparison of whole‐cell protein profiles with type‐strains indicated that the bacterial isolates belong to Pseudomonas viridiflava and P. syringae pv. syringae. In the pathogenicity tests, the first bacterium incited symptoms similar to those observed in the field. This is the first record of P. viridiflava as a pathogen of peach.
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