Incidencia y distribución del género Armillaria en viñedos de las cinco denominaciones de origen de vino de Galicia (noroeste de España) / Incidence and distribution of the genus Armillaria in vineyards of the five protected designation of origin wines in Galicia (Northwestern Spain)

Antecedentes: el género Armillaria, y más concretamente la especie Armillaria mellea, constituye un problema muy importante en el sector vitivinícola de Galicia, lo que ha ocasionado importantes reducciones del rendimiento de los viñedos en los últimos 15 años. Este hongo ataca al sistema radicular, causando un descenso del vigor y, finalmente, la muerte de la planta. Hasta la fecha, no se conoce ningún método químico o biológico que resulte efectivo contra el patógeno una vez que ha entrado en la planta. Objetivos: el objetivo principal del presente trabajo fue conocer la incidencia y distribución del género Armillaria mediante técnicas moleculares en las distintas zonas de cultivo de vid en Galicia, abarcando las cinco denominaciones de origen (DO) vitivinícolas gallegas (Rías Baixas, Ribeiro, Ribeira Sacra, Valdeorras y Monterrei). Métodos: se analizaron 624 muestras (483 de suelo y 141 de plantas de vid sintomáticas) mediante nested-PCR/RFLP, PCR-RFLP y análisis filogenéticos. Resultados: Armillaria mellea está ampliamente distribuida en viñedos de las cinco DO, con mayor incidencia en la DO del Ribeiro. Conclusiones: es necesario establecer medidas para reducir el avance de la podredumbre radicular causada por Armillaria mellea en las cinco DO de Galicia

Blackground: the genus Armillaria, specifically Armillaria mellea, is an important phytopathological problem in the wine sector in Galicia (NW Spain), having caused yield reductions in vineyards for the last 15 years. The fungus attacks the root system, resulting in a decrease in vigour, and eventually in the death of the plant. Up to now, there is no chemical or biological method really effective against the pathogen once it has infected the plant. Aims: the main objective of this work was to study the incidence and distribution of the genus Armillaria across the five Galician protected designation of origin (DO) wines (namely Rías Baixas, Ribeiro, Ribeira Sacra, Valdeorras and Monterrei) through the application of molecular techniques. Methods: a total of 624 samples (483 soils and 141 symptomatic vines) were analyzed by nested-PCR/RFLP, PCR-RFLP and phylogeny. Results: Armillaria mellea is widely distributed in vineyards of the five DO wines, with the highest incidence in the Ribeiro DO. Conclusions: preventive control measures against Armillaria mellea must be established in the five DO wines of Galicia, in order to reduce the advance of white root rot

[Incidence and distribution of the genus Armillaria in vineyards of the five protected designation of origin wines in Galicia (Northwestern Spain)]. / Incidencia y distribución del género Armillaria en viñedos de las cinco denominaciones de origen de vino de Galicia (noroeste de España).

BLACKGROUND: The genus Armillaria, specifically Armillaria mellea, is an important phytopathological problem in the wine sector in Galicia (NW Spain), having caused yield reductions in vineyards for the last 15 years. The fungus attacks the root system, resulting in a decrease in vigour, and eventually in the death of the plant. Up to now, there is no chemical or biological method really effective against the pathogen once it has infected the plant. AIMS: The main objective of this work was to study the incidence and distribution of the genus Armillaria across the five Galician protected designation of origin (DO) wines (namely Rías Baixas, Ribeiro, Ribeira Sacra, Valdeorras and Monterrei) through the application of molecular techniques. METHODS: A total of 624 samples (483 soils and 141 symptomatic vines) were analyzed by nested-PCR/RFLP, PCR-RFLP and phylogeny. RESULTS: Armillaria mellea is widely distributed in vineyards of the five DO wines, with the highest incidence in the Ribeiro DO. CONCLUSIONS: Preventive control measures against Armillaria mellea must be established in the five DO wines of Galicia, in order to reduce the advance of white root rot.

¹H-nuclear magnetic resonance analysis of the triacylglyceride composition of cold-pressed oil from Camellia japonica.

Camellia japonica (CJ) has oil-rich seeds, but the study of these oils has received little attention and has mainly focused only on their health properties. In the present work the relative composition of the fatty acid (FA) components of the triglycerides in cold-pressed oil from CJ is studied by ¹H-NMR. The results obtained were: 75.75%, 6.0%, 0.17% and 18.67%, for oleic, linoleic, linolenic and saturated FA respectively. Levels of C18 unsaturated FA found in CJ oil were similar to those reported for olive oils. We also checked the possibility of using ¹³C-NMR spectroscopy; however, the results confirmed the drawback of ¹³C over ¹H-NMR for the study of FA components of CJ triglycerides due to its low gyromagnetic ratio and its very low natural abundance.

In vitro selection of an effective fungicide against Armillaria mellea and control of white root rot of grapevine in the field.

Armillaria mellea (Vahl ex Fr) Kummer is an aggressive pathogen which causes white root rot in a wide range of hosts. Most chemicals tested so far against Armillaria, both in vitro and in the field, have not been effective in reducing fungal growth and/or preventing plant decline and mortality. In the present work the effects of four DMI (sterol demethylation inhibitor) fungicides, cyproconazole, hexaconazole, propiconazole and tetraconazole, and another six downwardly mobile systemic chemicals, azoxystrobin, cubiet (copper bis(ethoxy-dihydroxy-diethylamino)sulfate), fosetyl-Al, potassium phosphite, sodium tetrathiocarbonate (STTC) and 2-(thiocyanomethylthio)benzothiazole (TCMTB), on the mycelial growth of A. mellea were compared and evaluated; the product yielding the best results in in vitro experiments was selected to determine its efficacy in preventing decline and mortality of grapevines in the field. Best results on in vitro fungal growth reduction were obtained with the four azoles tested, in particular with cyproconazole and hexaconazole, achieving 67-72% mycelial growth inhibition at the lowest dose. Results obtained in the field showed that a dose of 50 mg AI litre(-1) of cyproconazole once or twice a year was efficient in controlling the disease even in vines seriously affected by the pathogen. However, further research is required to study minimum effective doses, residual effects and the convenience of the application of annual dressings in damaged vineyards, so as to gradually reduce the pathogen inoculum potential in soil and control the disease while reducing chemical residues in the plant and preventing development of fungal resistance.

Phylogenetic reassessment of Mycosphaerella spp. and their anamorphs occurring on Eucalyptus. II.

Species of Eucalyptus are widely planted as exotics in the tropics and Southern Hemisphere and to some extent in southern Europe, for timber and fibre production. Species of Mycosphaerella are commonly associated with leaves and twigs of Eucalyptus and can result in defoliation, dieback, and even tree death. In the present study, numerous isolates of Mycosphaerella species were collected from leaf litter, living leaves exhibiting leaf spot symptoms or severe Mycosphaerella leaf blotch symptoms. Isolates were compared based on DNA sequence data for the internal transcribed spacer region (ITS1 & ITS2) and the 5.8S gene. These data, together with characteristics of the fungal growth on three different media, morphology of the anamorph and teleomorph structures as well as ascospore germination patterns were used to describe 21 new species.