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Blueberry (Vaccinium spp.) plantings have significantly increased in Chile during the last decade and, currently, over 10,700 ha are cultivated throughout the country. Among other diseases, stem canker and dieback has been frequently observed in commercial plantations with incidences between 15 and 45%. The aim of this study was to identify and characterize Neofusicoccum spp. causing stem canker and dieback of blueberry in Chile. Three species, N. arbuti, N. australe, and N. parvum, were identified based on colony and conidia morphology, and nucleotide sequence analysis of the internal transcribed spacer (ITS) region (ITS1-5.8S-ITS2). These Neofusicoccum spp. were found alone or coexisting with Pestalotiopsis spp., Truncatella spp., or Phomopsis spp. Koch's postulates showed all Neofusicoccum spp. isolated from infected plants to be pathogenic when inoculated on blueberry fruit and twigs using both mycelia and conidia suspension. All blueberry cultivars tested, including, Brigitta, Bluecrop, Brightwell, Duke, Elliott, Misty, and O'Neal, were susceptible to Neofusicoccum spp. infection. Pathogenicity tests showed N. parvum to be the most virulent species and Elliott to be the most susceptible cultivar. This report represents the first description of N. arbuti, N. australe, and N. parvum as canker-causing agents on blueberry in Chile.

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Blueberry (Vaccinium spp.) has great economic importance in Chile, which currently has about 8,500 ha being cultivated. Recently, the presence of canker and dieback symptoms has been observed along the productive blueberry zone of Chile. Species of Pestalotiopsis and Truncatella were consistently isolated from diseased samples in 22 different locations. Therefore, the objective of this study was to identify and characterize the species of Pestalotiopsis and Truncatella associated with canker and twig dieback symptoms on blueberry. Forty-nine isolates were obtained on acidified potato dextrose agar in 2006 and 2007. These isolates were identified as Pestalotiopsis clavispora, P. neglecta, and Truncatella (=Pestalotia) angustata on the basis of colony characteristics and conidial morphology. This identification was verified by internal transcribed spacer analysis of DNA. Isolates of P. clavispora, P. neglecta, and T. angustata were pathogenic on apple, kiwifruit, and blueberry fruit. Similarly, isolates of P. clavispora were pathogenic on detached blueberry twigs of cv. O'Neal. Additionally, three selected isolates of P. clavispora induced light-brown canker lesions, surrounded by a reddish halo, and shoot dieback after twig inoculations on 2-year-old twigs of blueberry cvs. O'Neal, Bluecrop, Brightwell, Brigitta, Duke, Elliot, and Misty. Among blueberry cultivars, Brightwell and O'Neal were the most susceptible and Bluecrop and Misty the least susceptible, while Elliot, Brigitta, and Duke were moderately susceptible to P. clavispora. These pathogens were isolated consistently from inoculated plants, confirming Koch's postulates. P. clavispora was highly sensitive to fludioxonil and pyraclostrobin with a median effective concentration of 0.06 to 0.08 and 0.04 to 0.8 μg/ml, respectively. Therefore, the results of this study indicate that P. clavispora, P. neglecta, and T. angustata are primary pathogens that can cause canker lesions and dieback symptoms on blueberry not previously described in Chile. However, these results do not exclude that other species of these genera or other plant-pathogenic fungi (e.g., Botryosphaeria, Pestalotia, and Phomopsis spp.) may eventually be involved in this syndrome of blueberry.

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Soto-Alvear, S (Soto-Alvear, Sylvana)[ 1,2 ] ; Lolas, M (Lolas, Mauricio)[ 2 ] . Univ Talca, Fac Ciencias Agr, Talca, Chile.Soto-Alvear, S., Lolas, M., Rosales, I. M., Chavez, E. R., and Latorre, B. A. 2013. Characterization of the bull's eye rot of apple in Chile. Plant Dis. 97:485-490. Apple fruit in Chile are primarily produced for export to Asia, Europe, and the United States, which typically requires 15 to 40 days of maritime transportation. Therefore, Chilean apple production must fulfill the sanitization requirements imposed by the receiving countries. Under these circumstances, it was important to clarify the etiology of bull's eye rot that can severely affect 'Cripps Pink' apple and other late-harvest cultivars in Chile. Based on morphological characteristics and the partial sequence analysis of the internal transcribed spacer sequences and beta-tubulin genes, Neofabraea alba was identified as the causal agent of the bull's eye rot of Chilean apple. These results were further corroborated using species-specific primers. The incidence of bull's eye rot varied considerably; for instance, in 2009, 0.0 to 58.7% in 38 Cripps Pink orchards surveyed in the relatively arid and humid apple-growing areas of Chile, respectively. There was no evidence for the presence of N. malicorticis or N. perennans, which are commonly identified as causal agents of bull's eye rot in other apple-producing countries. Altogether, these data suggest that N. alba might represent the predominant and possibly the only cause of bull's-eye rot of Chilean apple