scholarly journals Forecasting oak decline caused by Phytophthora cinnamomi in Andalusia: Identification of priority areas for intervention

2018 ◽  
Vol 417 ◽  
pp. 122-136 ◽  
Author(s):  
Joaquín Duque-Lazo ◽  
Rafael María Navarro-Cerrillo ◽  
Hein van Gils ◽  
Thomas A. Groen
Keyword(s):  
Phytophthora Cinnamomi ◽  
Oak Decline ◽  
Priority Areas

scholarly journals Vegetative Propagation of Phytophthora cinnamomi-Tolerant Holm Oak Genotypes by Axillary Budding and Somatic Embryogenesis

Forests ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 841
Author(s):  
Maria Teresa Martínez ◽  
Francisco Javier Vieitez ◽  
Alejandro Solla ◽  
Raúl Tapias ◽  
Noelia Ramírez-Martín ◽  
...  
Keyword(s):  
Somatic Embryogenesis ◽  
Somatic Embryos ◽  
Phytophthora Cinnamomi ◽  
Shoot Proliferation ◽  
Holm Oak ◽  
Induction Medium ◽  
Axillary Shoot ◽  
Oak Decline ◽  
Shoot Cultures

Holm oak (Quercus ilex) is one of the most widely distributed tree species in the Mediterranean basin. High mortality rates have been observed in holm oak populations in the southwest of the Iberian Peninsula as a result of oak decline syndrome. Selection and propagation of genotypes tolerant to this syndrome could aid the restoration of affected areas. In this article, we report micropropagation and conservation procedures based on axillary budding and somatic embryogenesis (SE) of holm oak plants, selected for their tolerance to Phytophthora cinnamomi—the main biotic factor responsible for oak decline. Forced shoots were obtained from potted plants of eight different genotypes, and used as stock material to establish in vitro shoot proliferation cultures. Reliable shoot proliferation was obtained in seven out the eight genotypes established in vitro, whereas multiplication rates were genotype-dependent. The highest rooting rates were obtained by culturing shoots for 24 h or 48 h on rooting induction medium containing 25 mg L−1 indole-3-butyric acid, followed by transfer to medium supplemented with 20 µM silver thiosulphate. Axillary shoot cultures can be successful conserved by cold storage for 12 months at 4 °C under dim lighting. Shoot tips, excised from axillary shoot cultures established from tolerant plants, were used as initial explants to induce SE. Somatic embryos and/or nodular embryogenic structures were obtained on induction medium with or without indole-acetic acid 4 mg L−1, in two out the three genotypes evaluated, and induction rates ranged between 2 and 4%. Plantlet recovery was 45% after two months cold stratification of somatic embryos and eight weeks of culture on germination medium. Vegetative propagation of P. cinnamomi-tolerant Q. ilex trees is a valuable milestone towards the restoration of disease-affected areas.

scholarly journals Phytophthora cinnamomi as a Contributor to White Oak Decline in Mid-Atlantic United States Forests

Plant Disease ◽  
2014 ◽  
Vol 98 (3) ◽  
pp. 319-327 ◽  
Author(s):  
M. E. McConnell ◽  
Y. Balci
Keyword(s):  
United States ◽  
Fine Roots ◽  
Phytophthora Cinnamomi ◽  
United States Department ◽  
Oak Decline ◽  
White Oak ◽  
Phytophthora Spp ◽  
Oak Trees ◽  
Root Health ◽  
The Impact

To evaluate Phytophthora cinnamomi as a cause of white oak (Quercus alba) decline in mid-Atlantic forests, sampling was conducted at 102 sites from 2011 to 2012. Soil and roots from healthy and declining white oak trees were collected. Phytophthora spp. were isolated using baiting and CFU of P. cinnamomi quantified using wet-sieving. Fine roots were scanned and measured. Phytophthora spp. were isolated from 43% of the sites. P. cinnamomi was common; six other species were isolated infrequently. Little difference in lesion size existed on white oak seedlings inoculated with 32 isolates of P. cinnamomi; only 13 isolates caused significant mortality. Soils from white oak versus nine other hosts did not have significantly different CFU. P. cinnamomi was restricted to United States Department of Agriculture hardiness zones six and seven and never found in zone five. The presence of Phytophthora spp. in soil can be associated with white oak fine root health. When Phytophthora spp. were present, white oak trees in zones five and six had less fine roots. In mid-Atlantic oak forests, however, environmental conditions appear to play a key role in determining the impact of P. cinnamomi on the root system. P. cinnamomi alone does not appear to be a causal factor of white oak decline.

scholarly journals Association of Phytophthora cinnamomi with White Oak Decline in Southern Ohio

Plant Disease ◽  
2010 ◽  
Vol 94 (8) ◽  
pp. 1026-1034 ◽  
Author(s):  
Annemarie M. Nagle ◽  
Robert P. Long ◽  
Laurence V. Madden ◽  
Pierluigi Bonello
Keyword(s):  
Soil Moisture ◽  
Phytophthora Cinnamomi ◽  
Clay Content ◽  
Environmental Drivers ◽  
Quercus Alba ◽  
Oak Decline ◽  
White Oak ◽  
Population Densities ◽  
Exponential Relationship ◽  
Root Health

A decline syndrome and widespread mortality of mature white oak tree (Quercus alba) associated with wet and low-lying areas has been recently observed in southern Ohio forests. Previous studies have isolated Phytophthora cinnamomi from white oak rhizospheres. In 2008 and 2009, P. cinnamomi population densities in two healthy and two declining white oak stands at Scioto Trail State Forest were quantified and potential roles of three environmental drivers of Phytophthora spp.–induced decline were assessed: soil texture, soil moisture, and topography. Significantly higher P. cinnamomi propagule densities were found in declining stands in both years but propagule densities were not associated with soil moisture content. Trends in population densities were not correlated with soil moisture or topographic position within field sites. There was a positive, exponential relationship between overall P. cinnamomi population levels and soil moisture on a seasonal scale in 2008 but not 2009. Sites with greater soil clay content were associated with greater decline. Effects of P. cinnamomi inoculum and periodic flooding on root health of 1-year-old potted white oak trees grown in native soil mixes in the greenhouse were examined. Root systems of potted oak were significantly damaged by soil inoculation with P. cinnamomi, especially under flooding conditions. Results of these studies support the hypothesis that P. cinnamomi is a contributing agent to white oak decline in southern Ohio.

scholarly journals Factores ambientales en la distribución de la seca en la encina (Quercus ilex subsp. ballota) = Environmental Variables in the Distribution of La Seca Disease in the Holm Oak (Quercus Ilex Subsp. Ballota)

2018 ◽  
pp. 107
Author(s):  
Mario Corral Ribera ◽  
Concepción Fidalgo Hijano ◽  
Begoña Peco Vázquez
Keyword(s):  
Environmental Variables ◽  
Quercus Ilex ◽  
Phytophthora Cinnamomi ◽  
Abiotic Factors ◽  
Information Criteria ◽  
Holm Oak ◽  
Oak Decline ◽  
Topographic Wetness Index ◽  
Daphne Gnidium ◽  
Field Samples

La combinación de factores bióticos y abióticos (clima, orografía, litología, competencia interespecífica, etc.) y la patogenicidad de agentes como el hongo Phytophthora cinnamomi Rands han generado la enfermedad fitosanitaria denominada en España como la seca de encinas y alcornoques de la Península Ibérica. El objetivo del presente estudio es el análisis que desempeñan las variables ambientales en el desarrollo de dicha enfermedad y determinar cuáles tienen una mayor influencia en su propagación. Se toma como área de estudio el Monte de Valdelatas, Alcobendas, Madrid (hoja 534 del Mapa Topográfico Nacional a escala 1:50.000. Coordenadas UTM X: X: 442592.51, Y: 4487266.63 zona 30T). Se obtivieron muestras en campo de 100 árboles de Quercus ilex subsp. ballota (50 con apariencia saludable y 50 con síntomas aparentes de enfermedad) azarosamente ubicados en 7 transectos. En relación al modelo estadístico se empleó un modelo binomial cuya variable respuesta se definió como sano/enfermo, según la apariencia del árbol. Así mismo, se manejó el Criterio de Información de Akaike (AIC) con el fin de establecer el mejor modelo. En su caso, presentando un 44% de la varianza (D2 = 0.437) y un valor de 89.68 en AIC. Las principales variables ambientales que interfieren en la enfermedad fueron: proximidad a cursos fluviales, índice de humedad topográfico, cobertura de Daphne gnidium y Quercus ilex subsp. ballota y la edad de los individuos muestreados. Dada la pérdida en la masa forestal de Quercus debido a la enfermedad de la seca, es necesario comprender el comportamiento de dicha enfermedad, así como conocer los factores ambientales que contribuyen a su expansión, pudiendo llegar de tal modo a identificar algún factor inhibidor. The combination of biotic and abiotic factors (climate, orography, lithology, interspecific competition, etc.) and the pathogenicity of agents such as the fungus Phytophthora cinnamomi Rands has generated the phytosanitary disease known as the oak decline (la seca) in holm oak and cork oak stand of the Iberian Peninsula. The aim of this study is to analyse the role played by environmental variables in the development of this disease, and to determine which have a stronger influence in the spread of the disease. Data has been obtained from Monte de Valdelatas, Alcobendas, Madrid (sheet 534 national topographic map, scale 1:50.000, UTM coordinates X: 442592.51, Y: 4487266.63 zone 30T). Field samples were taken from 100 randomly selected Quercus ilex subsp. ballota individuals (50 with a healthy appearance and 50 that showed disease symptoms), located within 7 transects. In relation to the statistical model, in this work a binomial model was used. On it, the response variable was defined as healthy/unhealthy, depending on the appearance of each tree. Akaike Information Criteria (AIC) was used to define the quality of the model. We selected model obtained a score of 89.68 and accounts for approximately 44% of data variability (D2 = 0,437). The main environmental variables that impact disease were: proximity to river course, topographic wetness index, cover of Daphne gnidium and Quercus ilex subsp. ballota, and the age of the individuals. Given the loss of Quercus forest mass caused by the spread of the oak decline disease, detected in several countries, including Spain, it becomes necessary to adequately understand the different factors that contribute and, in some cases, is the cause of the expansion of the disease, as well as to identify any inhibiting factors.

scholarly journals Differences in the Response to Acute Drought and Phytophthora cinnamomi Rands Infection in Quercus ilex L. Seedlings

Forests ◽  
2018 ◽  
Vol 9 (10) ◽  
pp. 634 ◽  
Author(s):  
Francisco Ruiz Gómez ◽  
Alejandro Pérez-de-Luque ◽  
Rafael Sánchez-Cuesta ◽  
José Quero ◽  
Rafael Navarro Cerrillo
Keyword(s):  
Water Stress ◽  
Biomass Allocation ◽  
Root Rot ◽  
Tree Mortality ◽  
Quercus Ilex ◽  
Phytophthora Cinnamomi ◽  
Growth Patterns ◽  
Holm Oak ◽  
Stress Factors ◽  
Oak Decline

The sustainability of “dehesas” is threatened by the Holm oak decline. It is thought that the effects of root rot on plant physiology vary depending on external stress factors. Plant growth and biomass allocation are useful tools to characterize differences in the response to drought and infection. The study of physiological responses together with growth patterns will clarify how and to what extent root rot is able to damage the plant. A fully factorial experiment, including drought and Phytophtora cinnamomi Rands infection as factors, was carried out with Quercus ilex L. seedlings. Photosynthesis, biomass allocation and root traits were assessed. Photosynthetic variables responded differently to drought and infection over time. The root mass fraction showed a significant reduction due to infection. P. cinnamomi root rot altered the growth patterns. Plants could not recover from the physiological effects of infection only when the root rot coincided with water stress. Without additional stressors, the strategy of our seedlings in the face of root rot was to reduce the biomass increment and reallocate resources. Underlying mechanisms involved in plant-pathogen interactions should be considered in the study of holm oak decline, beyond the consideration of water stress as the primary cause of tree mortality.

scholarly journals Spatio-temporal analysis at landscape scale of the Iberian oak decline epidemic caused by Phytophthora cinnamomi

2020 ◽  
Author(s):  
Enrique Cardillo ◽  
Enrique Abad ◽  
Sebastian Meyer
Keyword(s):  
Process Model ◽  
Phytophthora Cinnamomi ◽  
Landscape Scale ◽  
Control Measures ◽  
Target Area ◽  
Natural Ecosystem ◽  
Oak Decline ◽  
Mixed Stands ◽  
Spatial Dispersal ◽  
Spatio Temporal

Phytophthora cinnamomi Rands is considered a main factor behind the Iberian oak decline (IOD). This epidemic is decimating Holm oaks (Quercus ilex L.) and cork oaks (Quercus suber L.) which are the keystone trees of a multipurpose, silvo-pastoral and semi-natural ecosystem of 3.1 million hectares in the south west of Europe. Forest diseases are characterized by pronounced spatial patterns, since many of the underlying ecological processes are inherently spatial. To improve the current understanding of such processes, we carried out a complete census of diseased sites via aerial imagery at landscape scale at four different dates over a period of 35 years. We validated our photographic interpretation of P. cinnamomi presence in-situ by subsampling soil and roots of diseased sites. To analyse the role of host population heterogeneities in shaping the spread of IOD, we used a ‘self-exciting’ spatio-temporal point process model. Its so-called epidemic component represents the inoculum pressure arising from nearby foci whereas its background component allows for sporadic infections from unobserved sources or disease transmission over larger distances. The best fit was obtained with a lagged power-law for the spatial dispersal kernel, where 49% of the infections triggered by an infected site occur within a distance of 250 meters. Both risk components were found to increase over time. The rate of sporadic infections appeared to be significantly lower in silvo-pastoral systems (dehesas) than in forests and higher in mixed stands and shrub encroached oak-lands. These results may have direct implications for IOD management, for example, the estimated spatial dispersal function helps to define a suitable target area for more efficient control measures. Our results also suggest that silviculture treatments aimed at controlling the density and species composition of oak stands, as well as the abundance of shrubs, could play a key role for disease management

scholarly journals The Use of qPCR Reveals a High Frequency of Phytophthora quercina in Two Spanish Holm Oak Areas

Forests ◽  
2018 ◽  
Vol 9 (11) ◽  
pp. 697 ◽  
Author(s):  
Beatriz Mora-Sala ◽  
Mónica Berbegal ◽  
Paloma Abad-Campos
Keyword(s):  
Phytophthora Cinnamomi ◽  
Phytophthora Species ◽  
Holm Oak ◽  
Oak Decline ◽  
Phytophthora Megasperma ◽  
Phytophthora Root Rot ◽  
Molecular Approaches ◽  
Isolation Techniques ◽  
Phytophthora Spp ◽  
Long Time

The struggling Spanish holm oak woodland situation associated with Phytophthora root rot has been studied for a long time. Phytophthora cinnamomi is considered the main, but not the only species responsible for the decline scenario. This study verifies the presence and/or detection of Phytophthora species in two holm oak areas of Spain (southwestern “dehesas” and northeastern woodland) using different isolation and detection approaches. Direct isolation and baiting methods in declining and non-declining holm oak trees revealed Phytophthora cambivora, Phytophthora cinnamomi, Phytophthora gonapodyides, Phytophthora megasperma, and Phytophthora pseudocryptogea in the dehesas, while in the northeastern woodland, no Phytophthora spp. were recovered. Statistical analyses indicated that there was not a significant relationship between the Phytophthora spp. isolation frequency and the disease expression of the holm oak stands in the dehesas. Phytophthora quercina and P. cinnamomi TaqMan real-time PCR probes showed that both P. cinnamomi and P. quercina are involved in the holm oak decline in Spain, but P. quercina was detected in a higher frequency than P. cinnamomi in both studied areas. Thus, this study demonstrates that molecular approaches complement direct isolation techniques in natural and seminatural ecosystem surveys to determine the presence and distribution of Phytophthora spp. This is the first report of P. pseudocryptogea in Europe and its role in the holm oak decline should be further studied.

scholarly journals Quercus suber Infected by Phytophthora cinnamomi. Effects at Cellular Level of Cinnamomin on Roots, Stem and Leaves

2008 ◽  
Vol 14 (S3) ◽  
pp. 146-147 ◽  
Author(s):  
I. Maia ◽  
C. Medeira ◽  
E. Melo ◽  
A. Cravador
Keyword(s):  
Phytophthora Cinnamomi ◽  
Plant Defence ◽  
Quercus Suber ◽  
Cellular Level ◽  
Holm Oak ◽  
Oak Decline ◽  
Defence Reactions

Phytophthora cinnamomi has been reported to be regularly associated with cork and holm oak decline. This oomycete secretes elicitins, a group of unique highly conserved proteins that can enhance plant defence reactions.

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