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1.
M. C. Rodríguez‐Molina L. M. Torres‐Vila A. Blanco‐Santos E. J. Palo Núñez E. Torres‐Álvarez 《Forest Pathology》2002,32(6):365-372
The emergence and survival of pregerminated holm oak (Quercus ilex) and cork oak (Quercus suber) acorns from two ecologically different dehesas (Mediterranean open woodlands) were studied in two soils from these stands naturally infected with Phytophthora cinnamomi, and in the same soils previously sterilized in the autoclave. Phytophthora cinnamomi was consistently isolated from the radicles of all unemerged and all emerged but dead seedlings from the unsterilized substrates. Seedlings of holm oak were more susceptible to P. cinnamomi than those of cork oak. Mortality of holm oak seedlings was significantly different depending only on soil treatment (sterilized or unsterilized), and it was 100% in unsterilized soils, independent of acorn provenance and soil origin. Mortality of cork oak seedlings was significantly different depending on the acorn origin and soil treatment, and on the interactions acorn origin × soil origin and soil origin × soil treatment. The demonstrated high susceptibility of holm and cork oak young seedlings to P. cinnamomi could be a limiting factor in Mediterranean open woodlands (dehesas) not only in natural regeneration processes but also when reforestation by direct sowing is implemented. 相似文献
2.
Oak decline that was affecting three holm oak sites in the province of Huelva (south‐western Spain) was studied during 1998–1999. The syndromes of dieback and sudden death have been observed and, in both cases, foliar symptoms were associated with root rot. Characterization of the fungal isolates from necrotic roots led us to identify Phytophthora cinnamomi A2 as consistently associated with the disease. The optimum growth temperatures of these isolates were very high (30°C). Inoculation tests under controlled conditions demonstrated the pathogenicity of the isolates on holm and cork oak seedlings. None of the other biotic factors of Mediterranean oak decline that have been previously described were found in the present study and so, in this case, the forest decline model does not seem to be necessary in order to explain the disease observed. The defoliation and mortality of the oaks was primarily caused by P. cinnamomi, although some abiotic factors such as alternating periods of drought and wet weather in the region may play an important role. 相似文献
3.
Since 2008, severe and widespread tree decline and mortality has been observed at the main growing Quercus ilex L. (holm oak) forest on Caprera Island, Italy. To clarify the symptomatology and aetiology of this phenomenon, field surveys and isolations from symptomatic trees were carried out in summer 2010. Affected trees exhibited crown thinning, branch dieback, sunken cankers, epicormic shoots, exudates on branches and trunk, root losses and sudden death symptoms. Four fungal species belonging to Botryosphaeriaceae family, namely Botryosphaeria dothidea, Diplodia corticola, D. seriata and Neofusicoccum parvum, were isolated from cankers on trunk and branches, whereas three species of Phytophthora, namely P. cinnamomi, P. cryptogea and P. gonapodyides, were isolated from fine roots and rhizosphere soil samples. Isolates were identified using both morphological analysis and DNA‐based techniques. Pathogenicity trials on holm oak seedlings showed that all the isolated species are pathogenic. D. corticola proved to be the most aggressive species. Our results provide the first evidence for a combined involvement of D. corticola and P. cinnamomi in the aetiology of holm oak decline in Italy and suggest that these pathogens are not only important contributing factors in the onset of long‐term tree decline, but also may cause the rapid devastation of extensive oak ecosystems. 相似文献
4.
Constança de Sampaio e Paiva Camilo-Alves Maria Ivone Esteves da Clara Nuno Manuel Cabral de Almeida Ribeiro 《European Journal of Forest Research》2013,132(3):411-432
Mortality events in cork and holm oaks have occurred in the Mediterranean basin since the beginning of the XX century, but severity of decline increased during the 1980s. By that time, the exotic soil borne pathogen Phytophthora cinnamomi was often recovered from declining stands and since then it has been considered the main factor associated with decline. This work analyses data concerning P. cinnamomi surveys in cork and holm oaks trees, pathogenicity tests carried out in controlled experiments, studies about the influence of site characteristics in tree decline and approaches to control the disease. Results of field surveys showed that the pathogen is widespread and pathogenicity tests suggested that host susceptibility to the pathogen is moderate when seedlings are in appropriate watering conditions, particularly cork oaks. Occurrence of decline is also associated with soil characteristics that interfere with root expansion and water retention. We assessed the relative importance of each factor involved in decline and revised the role of P. cinnamomi in cork and holm oak decline. 相似文献
5.
The effects of root damage associated with Phytophthora cinnamomi on water relations, biomass accumulation, mineral nutrition and vulnerability to water deficit were investigated in pedunculate oak (Quercus robur), red oak (Quercus rubra) and holm oak (Quercus ilex) saplings over two years. Comparison was made with sweet chestnut (Castanea sativa), a susceptible species to infection by P. cinnamomi, and with a resistant hybrid chestnut (Castanea crenata × C. sativa). Trees were inoculated in 1998 and were subjected to water shortage in 1999. All inoculated sweet chestnuts died before the application of water shortage. Hybrid chestnut, pedunculate oak and red oak displayed low root susceptibility to P. cinnamomi. In these species, water relations, aerial growth and mineral nutrition were slightly affected by inoculation. By contrast, holm oak was the most susceptible oak species to P. cinnamomi as inoculated well‐watered trees displayed the highest root loss (67%) and a 10% mortality. Root loss was associated with a decrease in predawn leaf water potential, a 61% reduction in stomatal conductance, a 55% reduction in aerial biomass, a decrease in leaf carbon isotope discrimination and reduced leaf N and P contents in comparison with controls. In hybrid chestnut and pedunculate oak, water shortage resulted in a similar decrease of predawn leaf water potential, stomatal conductance and aerial biomass in inoculated and non‐inoculated trees. In red and holm oaks, soil volumetric water content of inoculated trees subjected to water shortage remained high. The effects observed in those trees were similar to those of inoculated well‐watered trees and were probably the result of root infection only. 相似文献
6.
B. Scanu B. T. Linaldeddu A. Franceschini N. Anselmi A. Vannini A. M. Vettraino 《Forest Pathology》2013,43(4):340-343
An increasing decline and mortality of cork oak trees have been recently observed in central Italy and Sardinia Island. Following surveys conducted in three declining cork oak forests, a Phytophthora species was consistently isolated from soil samples collected from trees displaying different level of decline. Based on morphological features, growth rates at different temperatures and analysis of DNA sequences of the ITS region, all isolates were identified as Phytophthora cinnamomi Rands. This pathogen caused large brownish lesions on inoculated freshly cut branches of cork oak. It was re‐isolated from all infected tissues. These findings represent the first report of P. cinnamomi on cork oak trees in Italy. 相似文献
7.
Within a research project on quality of plants for forestation of agricultural lands, we studied the aetiology of a late seedling rot affecting holm oak (Quercus ilex ssp. ballota) in two forest nurseries in southern Spain. Major disease symptoms were foliage wilting and necrosis of feeder roots. Phytophthora cinnamomi, Phytophthora cryptogea and Phytophthora drechsleri were isolated from necrotic roots of holm oaks. Selected isolates of the three Phytophthora species were pathogenic to Quercus ilex ssp. ballota and Quercus suber seedlings in artificial inoculations. Soil flooding conditions were essential for infection and root rot development. There was no host specificity among the species, the isolates of P. cinnamomi being the most virulent in all inoculated plants. In these inoculations, Q. ilex ssp. ballota plants were more susceptible than those of Q. suber. This work is the first report of P. cinnamomi, P. drechsleri and P. cryptogea affecting Q. ilex ssp. ballota in forest nurseries. 相似文献
8.
M. C. Rodríguez-Molina A. Blanco-Santos E. J. Palo-Núñez L. M. Torres-Vila E. Torres-Álvarez M. A. Suárez-de-la-Cámara 《Forest Pathology》2005,35(6):411-422
The viability of 1-year-old holm oak (Quercus ilex) seedlings in a soil naturally infected with Phytophthora cinnamomi was studied during 2 consecutive years in a plot located in south-western Spain. In both years, total mortality during autumn and winter was not noticeable (<2.1%). In spring, mortality levels were higher (8.3–4.6%), especially the first year. A steep increase in total mortality occurred in summer, both in the first (11.4%) and second (24.2%) year, but mortality attributable to P. cinnamomi was 1.9 and 7.6%, respectively. Thus, 2 years after planting, total cumulative mortality was 43.4%, and that attributable to P. cinnamomi 9.6% (i.e. 22.1% of total mortality). Fungus-derived mortality followed a spatially aggregated pattern in the reforestation plot, suggesting a clustered distribution of the inoculum in the soil. Furthermore, mortality by P. cinnamomi was also associated with nearness of infected adult trees in the plot. Results obtained are discussed in the framework of seasonal water deficit, P. cinnamomi damage, weed competition and sanitation techniques to be used in declined holm oak stands in Spain. 相似文献
9.
The susceptibility of oak seedlings (Quercus palustris, Quercus robur, Quercus rubra) and chestnut seedlings (Castanea sativa) to Phytophthora cinnamomi was tested. The dynamics of infection was examined in plant material raised in a rhizotron. In the oak species, primary root tissues were susceptible whereas secondary cortical tissues showed some resistance to P. cinnamomi. Secondary cortical tissues of the tap root in C. sativa were susceptible. Inoculations with P. cinnamomi were performed both in situ and on excised roots of mature Q. rubra. In both cases, the resistance of Q. rubra roots and shoots was negatively correlated with diameter at the inoculation point. Small roots (l–5-cm diameter) were resistant, whereas collar and trunk were susceptible. In contrast to oak, small excised roots of mature C. sativa (0.7–2-cm diameter) were susceptible to P. cinnamomi. This may explain why P. cinnamomi does not induce a decline of the attacked oaks, but rather a trunk canker. 相似文献
10.
Temporal metabolic profiling of the Quercus suber–Phytophthora cinnamomi system by middle‐infrared spectroscopy 
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下载免费PDF全文 P. R. Hardoim R. Guerra A. M. Rosa da Costa M. S. Serrano M. E. Sánchez A. C. Coelho 《Forest Pathology》2016,46(2):122-133
The oomycete Phytophthora cinnamomi is an aggressive plant pathogen, detrimental to many ecosystems including cork oak (Quercus suber) stands, and can inflict great losses in one of the greatest ‘hotspots’ for biodiversity in the world. Here, we applied Fourier transform‐infrared (FT‐IR) spectroscopy combined with chemometrics to disclose the metabolic patterns of cork oak roots and P. cinnamomi mycelium during the early hours of the interaction. As early as 2 h post‐inoculation (hpi), cork oak roots showed altered metabolic patterns with significant variations for regions associated with carbohydrate, glycoconjugate and lipid groups when compared to mock‐inoculated plants. These variations were further extended at 8 hpi. Surprisingly, at 16 hpi, the metabolic changes in inoculated and mock‐inoculated plants were similar, and at 24 hpi, the metabolic patterns of the regions mentioned above were inverted when compared to samples collected at 8 hpi. Principal component analysis of the FT‐IR spectra confirmed that the metabolic patterns of inoculated cork oak roots could be readily distinguished from those of mock‐inoculated plants at 2, 8 and 24 hpi, but not at 16 hpi. FT‐IR spectral analysis from mycelium of P. cinnamomi exposed to cork oak root exudates revealed contrasting variations for regions associated with protein groups at 16 and 24 h post‐exposure (hpe), whereas carbohydrate and glycoconjugate groups varied mainly at 24 hpe. Our results revealed early alterations in the metabolic patterns of the host plant when interacting with the biotrophic pathogen. In addition, the FT‐IR technique can be successfully applied to discriminate infected cork oak plants from mock‐inoculated plants, although these differences were dynamic with time. To a lesser extent, the metabolic patterns of P. cinnamomi were also altered when exposed to cork oak root exudates. 相似文献
11.
Regeneration by seeds for cork oak (Quercus suber) and companion oaks (holm oak Quercus ilex and downy oak Quercus pubescens) is likely to be poor in the fire-prone Maures massif (southern France) but the causes are poorly known. Our objective was to assess the effective recruitment for these three oak species and their temporal pattern of recruitment, in order to determine the main limitation factors and the regeneration window of each species. We studied oak recruits (height <3 m) in naturally regenerated populations according to a gradient of fire recurrence and in five main vegetation types including shrublands and mixed mature woodlands. Fire recurrence was the main explanatory factor of oak recruitment, either directly or through vegetation type and microsite characteristics. The results indicate nil to low recruitment for holm oak and downy oak in shrublands, especially those recurrently burned and dominated by Cistus species. Cork oak recruited better than the other oaks in medium and high shrublands dominated by Erica arborea. In contrast, recruitment was high for holm and downy oak in mixed oak stands and mixed pine-oak stands that have not burned for decades. Microsite conditions such as coverage by litter and shrubs influenced oak recruitment, whereas landscape configuration and stand basal area had no influence. Our results suggest that strategic shrub-clearing, oak planting and protection of mixed oak woodlands as seed sources would help maintaining oak populations in the woodland–shrubland mosaic. 相似文献
12.
This study was initiated to investigate the possible role of Phytophthora species in white oak decline (Quercus alba) in southern Ohio at Scioto Trail State Forest. Surveys demonstrated the presence of four species of Phytophthora including one novel species. By far, the most common species was P. cinnamomi; P. citricola and P. cambivora were isolated infrequently. In few instances, P. cinnamomi was isolated from fine roots and necroses on larger roots. No special pattern of incidence was found, but P. cinnamomi was more commonly isolated from greater Integrated Moisture Index values suggesting moist lower bottomlands favour this Phytophthora species. When tree crown condition was examined relative to the presence of Phytophthora, no significant association was found. However, roots of declining P. cinnamomi‐infested trees had 2.5 times less fine roots than non‐infested and healthy trees, which was significantly different. The population densities of P. cinnamomi from declining trees were significantly greater than from healthy trees, suggesting increased pathogen activity that has the potential to cause dieback and decline and possibly the cause of a reduced fine root amount found on declining trees. 相似文献
13.
In different areas of Extremadura, Western Spain, soil samples were taken at the bottom of holm oak (Quercus ilex) trees that were showing decline symptoms. Half of each sample was sterilized, and acorns were sown in both sterilized and nonsterilized soil samples. The resulting seedlings were used as baits for the isolation of fungi. Seedlings growing on the natural, nonsterilized substrate were characterized by having a lower vegetative growth than the ones growing on the sterilized soil samples, and most of them died. Phytophthora dnnamomi was consistently isolated from their roots. Fusarium oxysporum was also isolated as well as different species of Pythium, although to a lesser extent. Pathogenicity tests were performed on holm oak seedlings with five different isolates of P. chinnamomi, with F. oxysporum, Pythium and with a mixture of the three fungi. All the inoculated seedlings with P. chinnamomi developed root rot and grew slowly, and 35.7% of them died up to the end of the experiments. P. chinnamomi was consistently isolated from their roots, indicating that this fungus is the causal agent of holm oak decline. However, F. oxysporum caused similar symptoms on oak seedlings as P. chinnamomi, and was isolated also from the roots, although its frequency was lower than that of. P. cinnamomi. 相似文献
14.
The recent decline of Mediterranean oak woodlands in SW Iberian Peninsula is related to insect pests which affect both cork oak (Quercus suber) and holm oak (Quercus rotundifolia). We identified twenty-six bird species as potential regular predators of twenty major pests by reviewing the diet of breeding, wintering and resident species in this ecosystem. Foraging guilds are strongly associated with predation at distinct stages of the pests’ life-cycle: ground-foragers prey on overwintering pupae and larvae of seed-borers, tree-foragers prey on eggs, larvae and pupae of defoliating and wood-boring pests, and aerial-sweepers prey on airborne imagines. Bird predation can cover the complete life-cycle of pest species because different species may be complementary due to a dissimilar exploitation of foraging niches and periods. Small generalist tree-foraging passerines are important pest predators given their high densities and widespread distribution in Mediterranean oak woodlands, but management practices can have a significant negative effect in their populations. 相似文献
15.
M. S. Serrano P. Fernández‐Rebollo P. De Vita M. D. Carbonero M. E. Sánchez 《Forest Pathology》2011,41(5):382-386
Phytophthora cinnamomi is a soilborne pathogen causing root rot in Mediterranean Quercus species growing in ‘dehesa’ rangeland ecosystems. Recently, it has been reported causing wilting and death of Lupinus luteus (yellow lupin), a spontaneous plant in southern Spain rangelands, but also frequently sowed for livestock grazing. In soils artificially infested with P. cinnamomi chlamydospores and planted with different cultivars of yellow lupin, a significant increase in the density of propagules was detected in comparison with the initial levels of inoculum and with the infested but not planted soil (control). In oak‐rangelands in which yellow lupine was planted, isolation and counting of colonies of P. cinnamomi from soil samples have shown the ability of this plant to maintain or even increase the inoculum density and thus facilitate the infection of trees. Results suggested that cultivation of yellow lupin in oak‐rangeland ecosystems should be avoided whether oak trees are affected by root disease caused by P. cinnamomi or not. This leguminous plant can act as an inoculum reservoir or even enhance inoculum soil levels available for oak root infections, exacerbating the oak decline severity in the region. 相似文献
16.
Potassium phosphite (PP) formulations registered as fertilizers are now prohibited in Spain. Therefore, we evaluated the systemic fungicide fosetyl‐aluminium (fos‐al) in comparison with PP, against root rot caused by Phytophthora cinnamomi in Quercus woodlands. The direct effect of both systemic fungicides was evaluated in vitro on P. cinnamomi mycelial growth. Protection of cork and holm oak against infection was also evaluated in planta. Metalaxyl was included in both in vitro and in planta experiments for comparison purposes. At 100 μg/mL, PP totally inhibited colony radial growth, in comparison with 75% achieved by fos‐al. At doses recommended by manufacturers, with fos‐al and metalaxyl applications, root symptoms remained similar to the uninfected control levels. Based on these results, fos‐al is a candidate substitute product for PP in Quercus woodlands for control of Phytophthora oak root disease. 相似文献
17.
Fine root dynamics of oak saplings in response to Phytophthora cinnamomi infection under different temperatures and durations 下载免费PDF全文
下载免费PDF全文 The belowground effects of Phytophthora cinnamomi on 1‐year‐old saplings of two common oak species in mid‐Atlantic US forests, white (Quercus alba) and red oak (Q. rubra), were examined after incubation in pathogen‐infested soilless potting mix. Fine root lengths (0–1.5 mm in diameter) of both oak species were quantified after incubation at successive 30‐day intervals up to 300 days, for a total of 10 incubation periods. In addition, colony‐forming units (CFU) of P. cinnamomi were quantified after white oak saplings were incubated in infested soilless potting mix at different temperature/duration combinations that reflect soil conditions present in the mid‐Atlantic United States. Impact of P. cinnamomi on fine root lengths of red and white oak saplings varied considerably over time. Significant periods of fine root loss occurred primarily during spring, when bud break and leaf flush began for both oak species. Red oaks had 17% fine root loss on average, while white oaks appeared more resistant to P. cinnamomi infection with a 2% decrease in fine roots over the course of the experiment. Phytophthora cinnamomi CFU declined significantly with exposure to all incubation temperatures except 8°C. This was in contrast to in vitro experiments, where the optimum temperature for mycelial growth was determined to be 21°C and above. Significant fine root loss caused by P. cinnamomi depended on plant phenology and the oak species tested. Extreme soil temperatures have a significant adverse impact on temporal changes of P. cinnamomi population. 相似文献
18.
The aim of this research was to study the changes in net photosynthesis and stomatal conductance values in 3‐year‐old cork oak and holm oak seedlings growing in natural conditions and inoculated with Apiognomonia quercina, Biscogniauxia mediterranea, Botryosphaeria corticola and Pleurophoma cava. Throughout the 4‐month experimental period, the evolution of visual external symptoms and the values of physiological variables were periodically recorded. All pathogens caused stem lesions around the infection point; however, the lesions caused by B. corticola were longer in both oak species. On cork oak seedlings, all pathogens induced a significant and gradual reduction in net photosynthesis and stomatal conductance values, whereas other physiological disturbances were induced only by B. corticola infections on holm oak seedlings. 相似文献
19.
Influence of water status of oak trees (Quercus rubra) on the development of Phytophthora cinnamomi lesions was studied. On agar media or excised inner bark, growth of P. cinnumomi was reduced by low water potentials. In contrast, on voung saplings or mature oak trees the development of P. cinnamomi lesions was not affected during a period of water stress. But after the end of the water stress treatment, susceptibility of the young saplings to P. cinnamoni increased. 相似文献
20.
A. Pérez‐Sierra C. López‐García M. León J. García‐Jiménez P. Abad‐Campos T. Jung 《Forest Pathology》2013,43(4):331-339
Oak decline has been a serious problem in Europe since the beginning of the twentieth century. In south‐west Spain, Quercus ilex and Q. suber are the main affected species, and their decline has been associated with Phytophthora cinnamomi. During the last 10 years, a severe decline of Q. ilex and Q. faginea accompanied by a significant decrease in the production of acorns affecting natural regeneration was observed in the eastern part of the Iberian Peninsula. Therefore, the aim of this study was to investigate the possible involvement of Phytophthora spp. in the decline. A forest in the Natural Park ‘Carrascar de la Font Roja’ in Comunidad Valenciana (eastern Spain), which is dominated by Q. ilex and Q. faginea, was surveyed during 2010–2011. Symptomatic trees showed thinning and dieback of the crown, withering of leaves and death. An extensive loss of both lateral small woody roots and fine roots and callusing or open cankers on suberized roots were observed. Soil samples containing fine roots were baited using both Q. robur leaves and apple fruits. Six Phytophthora species were isolated: P. cryptogea, P. gonapodyides, P. megasperma, P. quercina, P. psychrophila and P. syringae. These are the first records of P. quercina and P. psychrophila on Q. faginea, of P. quercina in Spain and of P. psychrophila in mainland Spain. A soil infestation trial was conducted for 6 months under controlled conditions with 1‐year‐old seedlings of Q. ilex and Q. faginea. Phytophthora cinnamomi was included in the pathogenicity test for comparison. The results showed that Q. ilex seedlings were generally more susceptible to infection than Q. faginea with P. cinnamomi being the most aggressive pathogen to both oak species. The two most commonly isolated Phytophthora species, P. quercina and P. psychrophila, also proved their pathogenicity towards both Q. ilex and Q. faginea. 相似文献