ReDivia - Repositorio Digital de l'Instit Valencià d'Investigacions Agràries
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Distribución de Brenneria spp. en la Comunidad Valenciana y especies forestales a las que afecta
Get PDFEl género Brenneria agrupa especies bacterianas que producen chancros con lesiones necróticas y exudados en plantas leñosas. En España, en los últimos años, se han identificado varias Brenneria sp. como responsables de chancros bacterianos en quercíneas (B. quercina), nogales (B. nigrifluens y B. rubrifaciens) y chopos (Brenneria sp.). En la Comunidad Valenciana también se han detectado focos de B. quercina en encinas de algunos parajes de importancia medioambiental, pero todavía se dispone de escasa información acerca de la incidencia de esta bacteriosis en nuestra Comunidad. Sin embargo, no existen referencias de la presencia de Brenneria spp. en nogal o chopo en la Comunidad Valenciana, aunque no se puede descartar su presencia o introducción a través de material vegetal. El objetivo del presente trabajo ha sido conocer la incidencia de dichas bacteriosis en nuestra Comunidad. Para ello, se han continuado las prospecciones en masas de quercíneas de distintos orígenes geográficos de la Comunidad Valenciana iniciadas en un estudio anterior, y se han centrado en aquellas zonas o especies del género Quercus en las que la bacteria no había sido detectada previamente. Además, se han iniciado prospecciones en otras especies forestales de interés para nuestra Comunidad, como Juglans regia y Populus spp
Evaluation of heated potassium sorbate solutions to control postharvest green and blue molds on commercially important citrus cultivars
No full textFlanking the major Plum pox virus resistance locus in apricot with co-dominant markers (SSRs) derived from candidate resistance genes
No full textPlum pox virus (PPV) is a potyvirus that causes sharka disease in infested stone fruit trees (Prunus species, peach, apricot, plum). In apricots, the resistance is controlled by a major quantitative trait locus that explains up to 70% of the phenotypic variance; it is localised in the upper part of linkage group 1. In this report, we transformed candidate genes that mapped in the region of the apricot resistance locus into polymerase chain reaction markers (SSCP and SSR) and tested for their co-localisation with the major PPV resistance locus in related and unrelated populations. Three populations of F1 and F2 individuals issued from crosses between the PPV-resistant cultivar ‘Stark Early Orange’ or ‘Goldrich’ and three susceptible parents were used in this study. Molecular-marker data were collected to determine the linkage relationship between the PPV resistance locus in apricots and markers that target candidate disease-resistance genes. In addition, SSR markers linked to resistance-gene candidates were mapped to positions flanking the PPV resistance locus in different apricot populations. Therefore, we demonstrate that this strategy helps to saturate the major genomic region controlling resistance to PPV in apricot with valuable co-dominant marker
Predation of 'Aonidiella aurantii' (Maskell) crawlers by phytoseiids
No full textFor our knowledge, there are few studies about the role of phytoseiids (Acari: Phytoseiidae) preying on Aonidiella aurantii (Maskell) (Hemiptera: Diaspididae) crawlers. The aims of the present work were to study in laboratory the development of three of the most abundant phytoseiids in Spanish citrus, Euseius stipulatus (Athias-Henriot), Neoseiulus californicus (McGregor) and Typhlodromus phialatus Athias-Henriot, and Amblyseius swirskii AthiasHenriot, recently introduced and released in Spain, feeding exclusively on A. aurantii crawlers. Furthermore, the ability of A. swirskii to reduce A. aurantii infestation on young citrus plants was studied under semi-field conditions by means of augmentative releases of this phytoseiid.
E. stipulatus was the only phytoseiid species tested which was not able to lay eggs on this prey. The progeny of N. californicus were not able to reach the protonymphal stage. On the other hand, T. phialatus and A. swirskii completed their development, from egg to adult preying exclusively on this prey. In the semi-field experiments, several doses of A. swirskii were tested. Once the phytoseiids were installed on the young trees, an artificial infestation of A. aurantii crawlers was promoted on each citrus plant. A significant reduction in A. aurantii infestation was observed in the trees where A. swirskii was previously released
Preventive and curative activity of combined treatments of sodium carbonates and Pantoea agglomerans CPA-2 to control postharvest green mold of citrus fruit
No full textPreventive and curative activity of 2 min dips in 3% sodium carbonate (SC) or sodium bicarbonate (SBC) aqueous solutions heated to 40 degrees C, alone or followed by the application of 2 x 10(8) CFU/mL of the biocontrol agent Pantoea agglomerans CPA-2(BA), were simultaneously evaluated for the control of postharvest green mold, caused by Penicillium digitatum, in artificially inoculated Lanelate and Valencia oranges. Fresh cells of BA proliferated inside rind wounds and their survival was not adversely affected by the presence of residues of SC or SBC. Green mold incidence after 7 d of incubation at 20 degrees C in rind wounds treated after fungal inoculation (curative activity) was 15%, 40%, or 15% in oranges treated with SC, BA, or SC + BA and 5%, 45% or 0% in oranges treated with SBC, BA, or SBC + BA, respectively, while it was about 90% in untreated control fruit. Green mold incidence in rind wounds treated before inoculation or reinoculation with the pathogen (preventive activity in pre-existing wounds) was 10% and 2%, or 15% and 8%, respectively, in oranges treated with SC and SC + BA, and 3% and 5%, or 20% and 5%, respectively, in oranges treated with SBC and SBC + BA. Green mold incidence in wounds inoculated after treatment (preventive activity in new wounds) was 55% and 25%, and 60% and 40% in oranges treated with SC and SC + BA, or SBC and SBC + BA, respectively. Additionally, the duration of the protective effect of SBC, BA, and SBC + BA was assessed in Eureka lemons and Valencia oranges. In both species, all three treatments effectively protected pre-existing rind wounds during 7 d of storage at 10 degrees C. After 0, 1, and 2 d, but not after 4 or 7 d, the protective effect of SBC was significantly inferior to that of BA and SBC+ BA. The integration of treatments is a promising approach to replace the use of conventional fungicides to control green mold in citrus packinghouses
Biological efficacy of two organophosphate insecticides against California red scale (Aonidiella aurantii Maskell) related to deposition parameters under laboratory conditions
Get PDFCalifornia red scale (Aonidiella aurantii Maskell) is a major economic pest of citrus in many countries. It is mostly controlled by organophosphate insecticides. The present work is aimed at adjusting an optimal dosage of two insecticides, in order to reduce the presence of residues on the fruit while assuring their efficacy. The paper establishes, under laboratory conditions, the relationship between the deposition characteristics of these insecticides and their efficacy. It takes into account the influence of the development stage of the scale to build curves of expected mortality against the amount of active ingredient deposition. The results demonstrate the importance of applying the insecticides in the early stages of the pest and shows that the amount of active ingredient has to be doubled or even quadruplicated when treating the adult phases (pre-pupae, young female, adult female) with respect to the amounts required for the young ones (L1 and L2)
Parasitism of Diachasmimorpha tryoni (Hymenoptera: Braconidae) on the host Ceratitis capitata (Diptera: Tephritidae) under Mediterranean temperatures
Get PDFCeratitis capitata (Wiedemann, 1824) is an endemic citrus pest since the 1930s in the East Coast of Spain, where biological control against the medfly was attempted in those first years without any success. In 2003 the Valencian Institute of Agricultural Research (IVIA) began a project to study new possibilities of use of Hymenoptera parasitoids in order to include them in Integrated Pest Management strategies against the Medfly in the Mediterranean Coast of Spain. With this aim the braconid wasp Diachasmimorpha tryoni (Cameron, 1911) was imported from Hawaii and a laboratory rearing of this species is in progress in the IVIA facilities. D. tryoni has a high parasitism and emergence rates at 25°C and at 21-25°C. The critical temperature of 30°C prevents the emergence of a new generation of parasitoids, but females are able to parasitize the host. When these high temperatures (25-30°C) are applied only for a few hours the parasitoid development is completed and adult emergence occurs. These results can explain the potential adaptability and survivorship of the parasitoid in the Mediterranean high temperatures when field releases are carried out to control the Medfly summer populations. Consequently, parasitism can be successful in the warmer months of the Mediterranean Spanish area
ACTA HORTICULTURAE
No full textSimplified versions of Penman-Monteith model can be applied for the water and climate management in greenhouse culture. They relate plant transpiration flux to solar radiation (Gin), leaf area and air vapour pressure deficit, VPD. Integrating the model-based algorithm in the greenhouse control system allows for a precise control of water supply. Fertigation systems such as those used for rose crops in greenhouses, allow implementing a model for plant nitrate uptake based on water uptake. Although for large periods of time, e.g. weeks or months, both water uptake and nitrate uptake are found to correlate positively, a model would prove useful for soilless culture if it were successful in predicting nitrate uptake at shorter periods. Nitrate and water uptake rates by a rose (Rosa x hybrida cv. Dallas) crop were measured hourly for 24 hour periods along the four seasons. Means of nitrate uptake rate (NUR, mmol NO(3)(-) h(-1) p(-1)) in the spring and autumn seasons were some 32% larger than in summer and winter. However, in summer and autumn the daily nitrate uptake efficiency, expressed as NUR per unit of plant dry weight (mu mol NO(3)(-) g(-1) p(-1)), was the largest of the year. This was likely due to the unbalanced dry matter distribution between root and shoot following the late spring pruning and to the subsequent nutritional response aiming to the recovery of the plant. Empirical models for NUR were developed by means of analysis of stepwise multiple regression. The regressor variables considered for the model were water uptake rate (WUR), Gin (simultaneously measured to nitrate uptake registration or accumulated in the previous 4 (Gin4), 8 (Gin8) and 12 (Gin12) hours), air temperature (airT) and VPD, both from inside the greenhouse, and temperature of the nutrient solution surrounding the root system (rootT). Three highly significant regression 2 models were obtained: NUR was related to WUR and rootT 2 in the summer (r(2)=0.81), to WUR in autumn (r(2)=0.85) and to VPD in spring (r(2)=0.85). Night root temperature is highest in the summer. This high root-zone temperature may pose a limiting condition for the nitrate transporters in the root as has been reported in the literature. VPD in spring is the lowest for the three seasons with highest significant models, which suggests that the crop can be in a better condition for a favourable water balance status. Maybe for this reason VPD is integrating other effects and results as the prevailing factor selected by the model in the spring
La fertilización y la fertirrigación, programas de nutrición, influencia sobre la programación
Get PDFLa Agricultura es un sector económico estratégico y multifuncional, cuya principal
finalidad es asegurar de forma indefinida una producción de alimentos y otras materias
primas esenciales (fibras textiles, etc.), en cantidad suficiente para cubrir las necesidades
de una población humana en progresivo aumento.
La fertilización es una técnica de cultivo que tiene como finalidad principal aportar al
suelo o a la planta directamente las enmiendas o productos fertilizantes (orgánicos e
inorgánicos) necesarios para lograr rendimientos satisfactorios de frutos de alta calidad,
con el mínimo de impacto ambiental y con el coste económico más bajo posible.
La fertilización del suelo es una técnica agrícola practicada desde los comienzos de la
agricultura, basada inicialmente en la utilización de los residuos orgánicos disponibles,
principalmente estiércoles, hasta que el descubrimiento de la síntesis del amoníaco por los
científicos Bosh-Haver en 1899 propició el desarrollo de la industria de los fertilizantes
inorgánicos.
La mejora en la práctica de fertilización derivada del uso generalizado de los fertilizantes
minerales a partir de la década de 1950, constituyó un hito relevante en el aumento
espectacular originado en la producción vegetal durante las últimas décadas, hasta el
extremo de que a la referida mejora tecnológica se le atribuye una contribución sustancial,
entre el 30 y 50% del aumento de alimentos generado en ese periodo (Isherwood, 2000).
Por otra parte, la fertirrigación o fertirriego consiste en la aplicación de los fertilizantes
conjuntamente con el agua de riego. Y aunque la fertirrigación puede practicarse también
en los sistemas de riego tradicionales (por inundación o a manta), el máximo desarrollo de
esta técnica se ha alcanzado en los sistemas de riego localizado (principalmente goteo).
Desde el inicio de los sistemas de riego por goteo, en la década de 1970, que tuvo
lugar en Israel, esta modalidad de riego se ha difundido rápidamente a lo largo de todos
los países agrícolas, particularmente en aquellos que presentan problemas graves de escasez
de agua.
La fertirrigación a través de sistemas de riego por goteo se ha revelado muy interesante
en cultivos de frutales, hortícolas, etc., originando mejoras en el rendimiento, en la calidad
de las cosechas, así como en la contaminación ambiental (Imas, 1997; Bar-Yosef, 1999;
Pomares, 2004).
En esta ponencia se exponen algunos aspectos básicos a tener en cuenta en los programas
de nutrición de los cultivos hortícolas, incluyendo también resultados de experiencias de
fertilización fosforada, potásica y orgánica. También se incluyen algunos programas
orientativos de fertirrigación para cultivos hortícolas al aire libre