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Viterbo, Italy

Lamichhane J.R.,University of Tuscia | Fabi A.,Hazelnut Research Center | Varvaro L.,Hazelnut Research Center
Acta Horticulturae | Year: 2014

A disease like physiological disorder of hazelnut known as "brown spots" was thoroughly studied for the first time from the Italian hazelnut growing areas. The quali-quantitative composition of the bacterial microflora associated to the syndrome was investigated. Six bacterial species, belonging to four different families were constantly isolated from the syndrome. On the basis of traditional and molecular assays, the species associated to brown spots were identified as Pantoea agglomerans, Microbacterium schleiferi, Xanthomonas arboricola pv. corylina, Pseudomonas fulva, Pseudomonas putida and Brenneria alni. Quantitative differences, statistically significant, were observed among the species. The populations, expressed as colony forming units per gram of the sample (CFU/g), ranged from a lowest value of 3.6×103 to a highest value of 2.7×104 respectively for Microbacterium schleiferi and Xanthomonas arboricola pv. corylina. Plant stress, caused by the adverse environmental conditions and inadequate agronomic and cultural practices, was the main cause of the brown spots during which the ubiquitous bacteria rapidly colonize and multiply the weakened plants. This phenomenon can be overcome if good agronomic and cultural practices are adopted. Source

Lamichhane J.R.,University of Tuscia | Lamichhane J.R.,Hazelnut Research Center | Varvaro L.,University of Tuscia | Varvaro L.,Hazelnut Research Center
Plant Pathology | Year: 2014

This review presents an overview of bacterial blight, the predominant and emerging hazelnut disease worldwide. Here, disease symptomatologies, disease cycle, epidemiology, detection and identification methods are thoroughly discussed. It also focuses on plant health regulations and control strategies. The information reported throughout the review could help to give a better understanding of the hazelnut-bacterial blight pathosystem. A thorough knowledge of this pathosystem is important for the effective management of bacterial blight across the hazelnut orchards of the world. © 2013 British Society for Plant Pathology. Source

Lamichhane J.R.,University of Tuscia | Lamichhane J.R.,Hazelnut Research Center | Grau P.,Institute of Agricultural Research | Varvaro L.,University of Tuscia | Varvaro L.,Hazelnut Research Center
Journal of Phytopathology | Year: 2012

Severe attacks of bacterial blight were observed on young plants throughout the hazelnut growing areas in Chile. The incidence of the disease in nurseries and fields ranged from 60-90%. The causal agent was identified as Xanthomonas arboricola pv. corylina, based on phenotypic and genetic tests. © 2012 Blackwell Verlag GmbH. Source

Lamichhane J.R.,University of Tuscia | Lamichhane J.R.,Hazelnut Research Center | Lamichhane J.R.,French National Institute for Agricultural Research | Bartoli C.,University of Tuscia | And 4 more authors.
PLoS ONE | Year: 2016

Pseudomonas avellanae (Pav) has been reported as the causal agent of bacterial decline and bacterial canker of hazelnut in Italy and Greece, respectively. Both hazelnut diseases were reported to be similar in terms of symptoms, severity and persistence. In this study, we found that both symptomatic and asymptomatic trees in the field were colonized by Pav. Multilocus Sequence Typing (MLST) analysis showed that Pav strains isolated during this study in Italy belong to the P. syringae phylogroup 1 and they are closely related to Pav strains previously isolated in Greece from hazelnut bacterial canker. On the other hand, strains isolated in earlier studies from hazelnut decline in Italy belong to both phylogroup 1 and 2 of P. syringae. Both phylogroup 1 strains of P. syringae from Greece and Italy are different than strains isolated in this study in terms of their capacity to excrete fluorescent pigments on different media. Despite the same plant genotype and cropping practices adopted, the incidence of hazelnut decline ranged from nearly 0 to 91% across our study sites. No disease developed on plants inoculated with Pav through wounding while leaf scar inoculations produced only mild disease symptoms. Based on our results and the previously reported correlation between pedo-climatic conditions and hazelnut decline, we conclude that hazelnut decline in central Italy could be incited by a combination of predisposing (adverse pedo-climatic conditions) and contributing factors (Pav). Because this is a true decline different from "bacterial canker" described in Greece, we refer to it as hazelnut decline (HD). © 2016 Lamichhane et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Source

Lamichhane J.R.,University of Tuscia | Lamichhane J.R.,Hazelnut Research Center | Fabi A.,University of Tuscia | Fabi A.,Hazelnut Research Center | And 3 more authors.
PLoS ONE | Year: 2013

Incidence of Xanthomonas arboricola pv. corylina, the causal agent of hazelnut bacterial blight, was analyzed spatially in relation to the pedoclimatic factors. Hazelnut grown in twelve municipalities situated in the province of Viterbo, central Italy was studied. A consistent number of bacterial isolates were obtained from the infected tissues of hazelnut collected in three years (2010-2012). The isolates, characterized by phenotypic tests, did not show any difference among them. Spatial patterns of pedoclimatic data, analyzed by geostatistics showed a strong positive correlation of disease incidence with higher values of rainfall, thermal shock and soil nitrogen; a weak positive correlation with soil aluminium content and a strong negative correlation with the values of Mg/K ratio. No correlation of the disease incidence was found with soil pH. Disease incidence ranged from very low (<1%) to very high (almost 75%) across the orchards. Young plants (4-year old) were the most affected by the disease confirming a weak negative correlation of the disease incidence with plant age. Plant cultivars did not show any difference in susceptibility to the pathogen. Possible role of climate change on the epidemiology of the disease is discussed. Improved management practices are recommended for effective control of the disease. © 2013 Lamichhane et al. Source

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