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Home » Publications » Papers in scientific journals and popular science publications » 2008

Pests and diseases detected in Spain
International Camellia Journal 2008, 40: 59-65

Salinero, C., Mansilla J.P., Abelleira, A., Aguín O., Pérez, R., Pintos, C.

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

ABSTRACT: In the last years, the number of pests and diseases found on camellia has gradually increased. This could be mainly due to the generalisation of international trade, and the subsequently increase in the exchange of plant material, which brought out the dissemination of pathogens. In addition, the environmental conditions in which they grow may also influence the occurrence of these pests and diseases. In the present work, a summary of the main pests and diseases occurring in Galicia isdescribed, putting special emphasis in the date of detection, the evolution of the diseases through the years, the current incidence and in some cases the suggested measures to control the diseases.

Keywords: pathogen, fungus, mites, insects, virus, bacteria, biological control, nematodes

Pollen production and germination in Camellia japonica cultivars
2008 American Camellia Yearbook

P. Vela¹, C. Salinero¹, P. Piñón¹ y M.J. Sainz²

¹ Estación Fitopatolóxica do Areeiro, Subida a la Robleda s/n, 36153 Pontevedra, Spain.
² Departamento de Producción Vegetal, Universidad de Santiago de Compostela, Campus Universitario, 27002 Lugo, Spain

RESUMEN: The selection of parents to obtain new Camellia japonica cultivars is hindered by the fact that flowers of many cultivars do not have operative reproductive organs and for there is not information on the fertility of the ornamental camellia cultivars. In the present work, the production and fertility of the pollen of 15 C. japonica cultivars was evaluated to select male parents to obtain interesting commercial cultivars. Flower samples were taken to remove anthers to obtain pollen, estimating the weight of the pollen released by each flower. Pollen germinability rate studies were carried out using fresh and frozen pollen. Cultivars 'Thelma Dale' and 'Silver Cloud' proved to be the best candidates to be used as parent pollen producers to create new cultivars, since they produce enough quantity of pollen and present a germinability higher than 40%.

Caracterización morfológica y molecular de las poblaciones de Cryphonectria parasitica en castaños de Galicia
Volumen 34 Nº4 2008 4º Trimestre Pag:581-594

O. Aguín1,D. Montenegro1, M.J. Sainz2, M. Hermida1, J.P. Mansilla1

1 Estación Fitopatolóxica do Areeiro, Subida a la Robleda s/n, 36153 Pontevedra, España
2 Departamento de Producción Vegetal, Universidad de Santiago de Compostela, Campus Universitario, 27002 Lugo, España

ABSTRACT: Chestnut blight caused by Cryphonectria parasitica is a fungal disease widely spreading in chestnut stands all over the world. At present, the only feasible perspectives for its control are based on the knowledge of the populations present in the affected stands and the use of hypovirulent strains. The biology of C. parasitica populations naturally occurring in chestnut stands in Lugo and Ourense provinces was then studied so as to determine the diversity of vegetative compatibility (vc) and mating types, as well as the occurrence of hypovirulent strains. A total of 610 isolates were obtained. Only 4 isolates, from Lugo province, showed the presence of ARNbc, characteristic of hypovirulent strains. Molecular characterization of hypovirus proved all hypovirulent strains belonged to Cryphonectria hypovirus 1 (CHV1-E).

The diversity of vegetative compatibility was very low. Nine vc types were found, five of them occurring in both provinces. Four types were compatible with the known European testers and the others were unreported vc types named E1, E2, E5, E6 and E7. Dominant vc types in both populations were E1, E2 and E5, being detected in 97% of the isolates. Four hypovirulent strains were found: two compatible with vc type E1, one with E2 and other with E5. The study of mating types showed that idiomorph MAT-1 was dominant in both populations.

Reproduction mainly asexual, together with the low diversity of vegetative compatibility types and the presence of hypovirulent strains compatible with dominant vc types, are factors favouring the application of a biological control program against chestnut blight in chestnut stands in Lugo and Ourense provinces.

Keywords: chestnut blight disease,Castanea sativavegetative compatibility, hypovirulence, mating types.

Diversity of vegetative compatibility types, distribution of mating types and ocurrence of hypovirulence of Cryphonectria parasitica in chestnut stands in NW Spain
Forest Ecology and Management 256 (2008) 973-980

D. Montenegroa, O. Aguína, M.J. Sainzb, M. Hermidaa, J.P. Mansillaa,b

a Estación Fitopatolóxica do Areeiro, Subida a la Robleda s/n, 36153 Pontevedra, España
b Departamento de Producción Vegetal, Universidad de Santiago de Compostela, Campus Universitario, 27002 Lugo, España

ABSTRACT: An extensive survey on chestnut stands in NW Spain was carried out to study the population biology of Cryphonectria parasitica in order to design future biological control programmes of chestnut blight based on the field introduction of native hypovirulent strains. Five hundred and thirty-nine Cryphonectria parasitica isolates, belonging to five populations (A Coruña, Lugo, Ourense, Pontevedra and León), were obtained. The diversity of vegetative compatibility was very low. Six vc types were found, each population showing only from 2 to 4 vc types. Two vc types were the known European testers EU1 and EU66, and the other four were undescribed vc types that were named E1, E2, E3 and E4. E1 was the dominant vc type in Lugo and Ourense populations, and EU1 in Pontevedra and León. Hypovirulent isolates (a total of 15) were only detected in the León population, all but one being compatible with the vc type EU1. Hypovirulent strains belonged to the French subtype F1 of the Cryphonectria hypovirus-1 (CHV1).

The study of the sexual compatibility in the León population showed that the idiomorph MAT-1 was present in most isolates (97%). In León, the simple structure of the population (reproduction mainly asexual and very low vc diversity) and the presence of hypovirulent strains compatible with the dominant vc type are factors that favour the application of biological control of chestnut blight in the near future.

Keywords: Castanea sativa; Biological control; dsRNA virus; Chestnut blight; Hypovirulence; Mating types.

Winter and spring ecology of Anaphes nitens, a solitary egg-parasitoid of the Eucalyptus snout-beetle Gonipterus scutellatus
International Organization for Biological Control (IOBC) 2008

Serena Sontolamazza-Carbone¹, Montserrat Pestaña Nieto¹, Rosa Pérez Otero², Pedro Mansilla Vázquez² and Adolfo Cordero Rivera³

¹ Sección de Fitopatología, Centro de Investigación e Información Ambiental de Lourizán, 36080 Pontevedra, España
² Estación Fitopatolóxica do Areeiro, Subida a la Robleda s/n, 36153 Pontevedra, España
³ Universidad de Vigo, EUET Forestal, Grupo de Ecoloxía Evolutiva e da Conservación, Campus Universitario, 36005 Pontevedra, España

ABSTRACT: We investigated the effects of temperature, photoperiod, food and host availability, and body size on the overwintering abilities of the egg parasitoid Anaphes nitens Girault (Hymenoptera, Mymaridae) under natural conditions. Seven groups of eighty females received one of four treatments (n = 20): (i) honey and hosts, (ii) water and hosts, (iii) honey, or (iv) water. Seven groups of forty males received only honey or water (n = 20). To test if short day-length is the main cue for larval dormancy, the experiment was replicated inside a climate chamber at 20_C and under a winter photoperiod. A. nitens overwinters because of quiescence or oligopause inside the hosts and increased adult longevity. Mean pre-emergence mortality was up to 26% indoors and 15.2% outdoors, males being more affected. Development time had a significant and positive effect on body size. Honey-fed females without hosts had the highest longevity (53 days). Mother's diet and size affected development time, body size, longevity, and fecundity of the progeny. The results confirm the good adaptation of the parasitoid to the environmental conditions of NW Spain and its ability to synchronize its life cycle with the phenology of the host.

Keywords: Body size, Development time, Longevity, Maternal effects, Quiescence

Primeros Estudios de la Diversidad y Persistencia de Nematodos Entomopatógenos en Suelos de Castaño en Galicia
IInd Iberian Chestnut Congress. Acta Hort. 784, ISHS 2008 Pag:181-186

A. Picoaga¹, A. Abelleira¹ and J. P. Mansilla¹

¹ Estación Fitopatolóxica de Areeiro, Subida a la Robleda s/n, Pontevedra, España

ABSTRACT:In Galicia, the economic importance of the chestnut tree (Castanea sativa Mill.) lies mainly in the fruit, but its production has decreased due to insects pest that reduce their quality and commercial value. Studies performed in this region so far, show that the species causing the most important damge are: Cydia splendana Hb., Curculio elephas Gyll y Cydia Fagiglandana Zel. An alternative method to control these pest is the use of entomopathogenic nematodes (NEP's) of the genus Steinernema and Heterorhabditis. These nematodes are pathogenic to many insect species and are symbiotically associated with bacteria that kill the host insect within 24-48h.

In this study soil samples from chestnut tree were collected to investigate the natural occurrence of NEP's adapted to our climatic and soil conditions. A test of persistence in the field was also carried out to know the nematodes performance and their possible application to control chestnut insect pest. In sampling soils were detected infective juveniles indentified by morphological and molecular studies as Heterorhabditis bacteriophora. It is the first record of this specie in the soil of chestnut growing areas in Spain. The results obtained in the test of persistence demonstrate that the infective juveniles survive in the soil, in the studied conditions of temperature, humidity and texture until 132 days, time enough to act against chestnut pests.

Keywords: Biological control, Cydia spp., Curculio elephas, Steinernema sp., Heterorhabditis sp.

A selective PCR-based method for the identification of Phytophthora hibernalis Carne
Spanish Journal of Agricultural Research 2008 6(1) Pag:78-84

D. Montenegro¹, O. Aguín¹, C. Pintos¹, M. J. Sainz² and J. P. Mansilla¹²

¹ Estación Fitopatolóxica de Areeiro, Subida a la Robleda s/n, Pontevedra, España
² Departamento de Producción Vegetal, Universidad de Santiago de Compostela, Campus Universitario, 27002 Lugo, España

ABSTRACT: Preharvest and postharvest brown rot of citrus fruit is responsible for important economic losses thoroughout the world. The disease is commonly caused by several species of Phytophthora. In Spain, citrus brown rot is mainly caused by P. citrophthora, but in the last years outbreaks of the disease in lemon and sweet orange caused by P. hibernalis Carne have been recorded in northwestern citrus-growing areas. In this work, a PCR method has been developed for the diagnostic of P. hibernalis either from isolated mycelia or directly from fruit lesions. One specific primer pair, PHIB1 and PHIB2, was designed from the nucleotide sequences of ITS1 and ITS2 regions. The two primers amplified a 407-bp fragment from the genomic DNA of P. hibernalis that was sequenced (Acc. No. AY827556). Results demonstrated that PCR amplification of ITS regions by primers PHIB1 and PHIB2 followed by DNA sequencing can provide a rapid, selective and reliable identification of P. hibernalis.

Additional keywords: Citrus, diagnostics, fruit brown rot, oomycetes, specific primers.