Consejo Superior de Investigaciones Científicas
Ver esta página en español
Ver esta páxina en galego
Browse this page in english
Home » Publications » Papers in scientific journals and popular science publications » 2011

First Report of Bacterial Canker of Kiwifruit Caused by Pseudomonas syringae pv. actinidiae in Spain
Plant Disease DOI: 10.1094/PDIS-06-11-0537
Publication Acepted 31-08-2011

Mrs. Adela Abelleira Argibay¹, Dr. María Milagros López², Mr. Javier Peñalver Navarro², Dr. Olga Aguín Casal¹, Dr. José Pedro Mansilla Vázquez¹, Mrs. Ana Picoaga Montoussé¹ y Mrs. María José García Fernández¹

¹ Deputación Pontevedra, Estación Fitopatolóxica do Areeiro, Subida a la Robleda s/n, Pontevedra, Spain, 36153
² IVIA, CPVYB, Valencia, Spain, 46113

ABSTRACT: Bacterial canker of kiwifruit caused by Pseudomonas syringae pv. actinidiae was first described in Japan and Korea, and is currently an emerging disease which causes major losses in China, Italy, New Zealand, France, Portugal and Chile. Actinidia chinensis especially cvs. Jin Tao and Hort 16A seem to be more susceptible than green kiwifruit (Actinidia deliciosa) cvs. Hayward and Summer. The bacterium affects both male and female woody vines, with young vines being more susceptible. The most characteristic symptoms that appear in early spring are reddish-orange or white colored exudates associated with cankers and wounds in branches and/or trunk, as well as brown leaf spots, buds and fruits are also affected. Most Spanish kiwifruit is cultivated in Galicia (NW Spain), where the main cultivar is Hayward. In 2010 the first plantation of cv. Jin Tao and one plantation of cv. Summer were established in this area close to Hayward woody vine. In early spring 2011, 80% of the vines of both species showed symptoms of the disease The bacterium, P. syringae pv. actinidiae, was reisolated from symptomatic plants and biochemical tests and molecular tests were performed. Pathogenicity tests were also performed by inoculating healthy vines with the bacterium in which symptoms began to appear five days later whereas uninoculated control vines remained healthy. The kiwifruit orchard with affected plants was eradicated (25 ha). To our knowledge, this is the first report ofP. syringae pv. actinidiae in Spain.

Primera cita en España de Psyllaephagus bliteus Riek (Hymenoptera, Encyrtidae), parasitoide de Glycaspis brimblecombei Moore (Hemiptera, Psyllidae)
Volume 37 Nº1 2011 Page:37-44

R. Pérez-Otero¹, P. Borrajo², J.P. Mansilla¹, F. Ruiz²

¹ Estación Fitopatolóxica do Areeiro. Subida a la Robleda s/n. 36153 Pontevedra.
² Centro de Investigación Forestal de ENCE. Crtra. A-5000 km 7,5. 21007 Huelva.

RESUMEN: This work is the first report on the occurrence in Spain of Psyllaephagus bliteus Riek (Hymenoptera, Encyrtidae) an specific parasitoid of Glycaspis brimblecombei Moore (Homoptera, Psyllidae) in the province of Huelva (SW Spain). The parasitoid is native from Australia and is being used as biological control agent of the suck psillid in many countries.

Palabras Clave: Biological Control, eucalypt, Huelva, psyllid.

First Report of Cankers and Dieback Caused by Neofusicoccum mediterraneum and Diplodia corticola on Grapevine in Spain
Plant Disease October 2011, Volume 95, Nº10, Page: 1315

C. Pintos Varela, V. Redondo Fernández, O. Aguín Casal y J. P. Mansilla Vázquez

Estación Fitopatolóxica Do Areeiro, Deputación Pontevedra, Subida a la Robleda s/n. 36153 Pontevedra, Spain

ABSTRACT: In November 2010, four grapevine plants of cv. Crimson from a vineyard located in Sevilla (south Spain) revealed trunk cankers. Several pathogens were isolated, including Cylindrocarpon liriodendri (2), Phaeoacremonium aleophilum (2), Pleurostomophora richardsiae, Neofusicoccum parvum, and Botryosphaeria dothidea (2). Among Botryosphaeriaceae fungi isolated on potato dextrose agar (PDA) were two types that did not fit the above mentioned species. Isolates of type 1 produced an abundant, gray mycelium with a diurnal zonation that gradually became dark olivaceous. Mycelium growth occurred from 5 to 37°C with an optimum at 28°C. Conidia were hyaline, fusiform, aseptate, thin walled, but gradually became obscured and septate with age, and measured (18.4-) 21.4 (-24.3) × (4.2-) 5.5 (-7.2) µm with a length/width (L/W) ratio of 4.0 ± 0.5 (n = 100). Isolates of type 1 were identified as N. mediterraneum (3). Single-spore cultures of type 2 developed a whitish, dense, aerial mycelium and remained white up to 10 days on PDA and darkened to gray thereafter. Mycelium growth occurred from 3 to 37°C with an optimum at 29 to 30°C. Conidia were hyaline, aseptate, thick walled, oblong to cylindrical, sometimes becoming light brown and one or two septate after discharge, and measured (24.6-) 30.2 (-42.8) × (10.9-) 14.3 (-18.6) µm with a L/W ratio of 2.1 ± 0.2 (n =100). Isolates of type 2 were identified as Diplodia corticola (1). Nucleotide sequences of the ribosomal internal transcribed spacer (ITS) region and the ß-tubulin genes were used to confirm the identifications through BLAST searches in GenBank. Comparison of the sequences of types 1 and 2 showed 99 to 100% homology with N. mediterraneum (HM443604 (4) and GU251836) and D. corticola (AY268421 (1) and EU673117), respectively. Representative sequences of N. mediterraneum (JF949757 and JF949756) and D. corticola (JF949758 and JF949759) were deposited in GenBank. The pathogenicity of one representative isolate of each of N. mediterraneum and D. corticola was confirmed by inoculating 10 detached grapevine canes (averaging 12 mm in diameter and 30 cm long) per isolate. A shallow wound was made with a scalpel on the internodes. A colonized 6-mm agar plug, from the margin of an actively growing colony, was inserted in every wound and sealed with Parafilm. Ten grapevine canes controls received only sterile PDA agar plugs. Canes were maintained at 25°C and 70% humidity. After 5 weeks, all inoculated canes developed cankers and pycnidia around the inoculation site. Vascular necroses that developed on the inoculated canes were an average of 28.6 mm for N. mediterraneum and 27.7 mm for D. corticola. One-way analysis of variance and Tukey's test confirmed significant differences in the extent of vascular necroses. The average necroses length in the inoculated canes was significantly greater (P < 0.05) than the average length of discoloration induced by the simulated inoculation process in the control. Both pathogens were reisolated from all inoculated plants but not from controls. To our knowledge, this is the first report of N. mediterraneum and D. corticola as pathogens on grapevine in Spain.

Survival time analysis of Pinus pinaster inoculated with Armillaria ostoyae: genetic variation and relevance of seed and root traits
European Journal of Plant Pathology Volume 130, Nº4, Page: 477-488

Alejandro Solla1; Olga Aguín2; Elena Cubera1; Luís Sampedro3; J. Pedro Mansilla2; Rafael Zas4

1Ingeniería Técnica Forestal. Universidad de Extremadura, Avenida Virgen del Puerto 2, 10600-Plasencia, Spain
2Estación Fitopatolóxica do Areeiro, Deputación de Pontevedra – Unidad Asociada MBGCSIC, Subida a la Robleda s/n, 36153-Pontevedra, Spain.
3Centro de Investigación Forestal de Lourizán – Unidad Asociada MBG-CSIC, Apdo. 127, 36080-Pontevedra, Spain.
4Misión Biológica de Galicia, CSIC, Calle Carballeira 8, 36143-Pontevedra, Spain

ABSTRACT: Results of a greenhouse Armillaria ostoyae inoculation experiment, designed for screening resistant Pinus pinaster genotypes and for exploring the role of different phenotypic traits in seedling susceptibility, are reported. The experiment included 39 open-pollinated pine families that comprised a random subset of the breeding population of P. pinaster in Galicia (NW Spain). We employed a non-parametric survival-time analysis to analyze patterns of survival times during 14 months after inoculation with a local A. ostoyae strain. Results indicate (i) a significant correlation between seed weight and tree susceptibility, with seedlings originating from large seeds being more susceptible, (ii) a positive family mean correlation between secondary root weight and size and median life expectancy, and (iii) genetic variation of tree tolerance to A. ostoyae, with some families surviving significantly longer than others. Less susceptible families could be used in breeding programmes or directly in forest plantations to reduce the losses caused by A. ostoyae. Large within-family variation in tolerance to the disease was also observed, suggesting that non additive genetic variance was also important. Although being infected, 32 out of the 1200 inoculated trees survived the fungus infection. These tolerant genotypes comprise an attractive collection to further investigate genetic, phenotypic and environmental factors affecting pine susceptibility to Armillaria root rot.

Keywords: Tree resistance – Pine – Screening – White root rot – Root density

Detection of Bursaphelenchus Xylophilus, Causal Agent of Pine Wilt Disease on Pinus pinaster in Northwestern Spain
Plant Disease June 2011, Volume 95, Nº6, Page: 776

A. Abelleira, A. Picoaga, J. P. Mansilla y O. Aguin

Estación Fitopatolóxica do Areeiro, Subida a la Robleda s/n, 36153 Pontevedra.

ABSTRACT: The present work reports the first detection of the pine wood nematode Bursaphelenchus xylophilus in Northwestern Spain; a quarantine organism which is causing serious damage to pines worldwide. In Europe, it was first detected in Portugal in 1999 and in Spain in 2008. Since then, several measures were carried out by the European countries to control the pathogen. 1999, 5,155 samples were analyzed both morphologically and molecularly to monitor the presence of the pathogen in the northern part of Spain. B. xylophilus was detected from a decayed mass of P. pinaster from the As Neves Municipality (Pontevedra, Galicia) in 2010. This area is one of the most productive and important region of Spain for forestry.

First Report of Dieback on Hybrid Rhododendrons Caused by Neofusicoccum luteum and N. parvum in Spain
Plant Disease February 2011, Volume 95, Nº2, Page: 221

C. Pintos Varela, V. Redondo Fernández, J.P. Mansilla Vázquez y O. Aguín Casal

Estación Fitopatolóxica do Areeiro, Subida a la Robleda s/n, 36153 Pontevedra.

ABSTRACT: During the conducting of Phytophthora ramorum surveys at Galician public parks (northwestern Spain) in 2010, established Rhododendron spp. plants were observed to be exhibiting leaf spots and necrosis, shoot blight, and cankers and dieback of shoots and branches. N. luteum and N. parvum were identified from these samples first using morphological techniques and then the diagnosis was confirmed by DNA sequences analysis. Pathogenicity of each isolate of N. luteum and N. parvum was confirmed by inoculating four 3-year-old Rhododendron spp. seedlings grown in pots. N. luteum and N. parvum were reisolated from all inoculated plants but not from the controls. To our knowledge, this is the first report of N. luteum and N. parvum on Rhododendron spp. in Spain.