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 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 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.

Control of Phytophthora Root Rot in Field Plantings of Fraser Fir with Fosetyl-Al and Mefenoxam

2006 ◽  
Vol 7 (1) ◽  
pp. 25 ◽  
Author(s):  
D. M. Benson ◽  
J. R. Sidebottom ◽  
J. Moody
Keyword(s):  
Root Rot ◽  
Tree Mortality ◽  
Phytophthora Cinnamomi ◽  
Flood Plain ◽  
Treatment Programs ◽  
Phytophthora Root Rot ◽  
Rainfall Events ◽  
Fraser Fir ◽  
Growing Seasons ◽  
Western North Carolina

Fungicides were evaluated for control of Phytophthora root rot for five growing seasons in two field plantings of Fraser fir (Abies fraseri) affected by Phytophthora cinnamomi in western North Carolina. At the first site, which had a fairly well-drained soil, treatment programs with Aliette (5 lb/100 gal, three applications per year), Subdue Maxx (3.7 fl oz/1.15 gal/1000 ft2, two applications per year), and Subdue GR (5.75 lb/1000 ft2, two applications per year) maintained low rates of mortality (< 10%) for three growing seasons, whereas tree mortality in the untreated plots reached 13 and 37% by the second and third growing seasons, respectively. At the second site, which was in a flood plain, disease did not develop during the first 2.5 years, even in untreated control plots. However, mortality increased rapidly following several high-rainfall events, but none of the fungicides had any effect on disease development. Apparently, at least under conditions not overly conducive to the disease, the fungicide treatment programs can delay the onset of high mortality rates caused by P. cinnamomi in Fraser fir for up to three growing seasons. Accepted for publication 23 February 2006. Published 31 March 2006.

The Involvement of Phytophthora Root Rot and Drought Stress in Holm Oak Decline: from Ecophysiology to Microbiome Influence

2019 ◽  
Vol 5 (4) ◽  
pp. 251-266 ◽  
Author(s):  
Francisco José Ruiz-Gómez ◽  
Alejandro Pérez-de-Luque ◽  
Rafael María Navarro-Cerrillo
Keyword(s):  
Drought Stress ◽  
Root Rot ◽  
Holm Oak ◽  
Oak Decline ◽  
Phytophthora Root Rot

scholarly journals Phytophthora ramorum on Quercus ilex in the United Kingdom

Plant Disease ◽  
2005 ◽  
Vol 89 (11) ◽  
pp. 1241-1241 ◽  
Author(s):  
S. Denman ◽  
S. A. Kirk ◽  
C. M. Brasier ◽  
V. C. Barton ◽  
K. J. D. Hughes ◽  
...  
Keyword(s):  
United Kingdom ◽  
Tree Mortality ◽  
Quercus Ilex ◽  
Ornamental Plants ◽  
The United States ◽  
European Population ◽  
Phytophthora Ramorum ◽  
Holm Oak ◽  
The United Kingdom ◽  
Morphological Studies

Phytophthora ramorum causes bleeding cankers of trunks of trees native to the west coast of the United States (i.e., Quercus kelloggii, Q. parvula var. shrevei, and Lithocarpus densiflorus). In the United Kingdom so far, bleeding cankers caused by inner bark infections have been found on Aesculus hippocastanum, Fagus sylvatica, Q. cerris, Q. falcata, and Q. petraea ( http://rapra.csl.gov.uk [2005]). Shoot tip dieback (ramorum dieback) and foliar necrosis (ramorum leaf blight) are other diseases caused by the pathogen on understory and ornamental plants (3). Inoculum is produced on infected shoots and leaves of foliar hosts but not on bole cankers (1). Foliar hosts are thus critical in initiating and maintaining epidemics of tree mortality resulting from lethal bark cankers. Ramorum dieback and blight occurs in Europe on genera Rhododendron, Camellia, Kalmia, Pieris, and Viburnum (http://rapra.csl.gov.uk [2005]), and now we report these diseases on foliage and shoots of holm oaks (Quercus ilex) in Cornwall (UK). First discovered in November 2003, infected young leaves had a water-soaked, dull gray appearance, and petioles were blackened. Lesions started at leaf margins, tips, or petioles, often progressing into the midrib veins. Initial infections also occurred on shoots and extended into the petioles. If shoots were infected, they were blackened at first, but later in the season clusters of dry, dead leaves and twigs characterized branch tips. Infected mature leaves bore dry, reddish-brown, restricted lesions. P. ramorum (A1 sexual compatibility type belonging to the European population) was isolated and confirmed by morphological studies, ITS sequence (GenBank Accession No. AY924253), and amplified fragment length polymorphism analyses. Lesions developed on detached leaves dipped for 10 sec in inoculum (4 × 105 zoospores per ml) and incubated in moist chambers at 20°C for 6 days (2). Two isolates were used (four leaves per isolate). The pathogen was reisolated, and the tests were repeated twice. Koch's postulates were also successfully completed once on foliage attached to saplings. To our knowledge, this is the first report of P. ramorum on holm oak. So far, at least 24 holm oaks are infected at various woodland and garden sites in the United Kingdom; infected rhododendrons have also been found at these sites. P. ramorum has also been recorded on saplings in nurseries. The high sporulation potential, the evergreen nature of leaves, and susceptible shoots indicate that holm oak could be a significant source of inoculum for other hosts. References: (1) J. M. Davidson et al. Phytopathology 95:587, 2005. (2) S. Denman et al. Plant Pathol. 54:512, 2005. (3) E. M. Hansen et al. Plant Dis. 89:63, 2005.

Environmental, biological and human drivers of the dieback of an evergreen Mediterranean forest

2020 ◽  
Author(s):  
Paolo De Angelis ◽  
Dario Liberati ◽  
Diego Giuliarelli ◽  
Loredana Oreti ◽  
Andrea Vannini
Keyword(s):  
Tree Mortality ◽  
Quercus Ilex ◽  
Central Italy ◽  
Mixed Forest ◽  
Forest Stand ◽  
Stress Factors ◽  
Ambrosia Beetle ◽  
Carbon Uptake ◽  
Typical Structure ◽  
General Decline

&lt;p&gt;Forests play a key role in the climate system thanks to their large carbon uptake and storage. On the other hand, forests are vulnerable to climate extremes and pest attacks, causing early tree mortality which in turn could reduce their carbon uptake capacity.&lt;/p&gt;&lt;p&gt;Early tree mortality is often associated to a complex interaction of predisposing stress factors (poor site quality, unfavourable stand conditions), inciting factors (frost, drought, mechanical damage) and contributing factors (fungi, insect borers).&lt;/p&gt;&lt;p&gt;In this context, the aim of the present work was to investigate the processes underlying the tree mortality observed in an evergreen mixed forest stand dominated by Quercus ilex, located in the Circeo National Park (central Italy).&lt;/p&gt;&lt;p&gt;The forest has the typical structure of an old-coppice not more managed (actual rotation time about 2 times that the normal), and was recently (2016) affected by an outbreak of Asian ambrosia beetle (Xylosandrus compactus) and Granulate ambrosia beetle (Xylosandrus crassiusculus) that caused an extensive trees crown browning. In 2019, plots were set in the area to monitor the beetle population dynamic and their impact on tree mortality. In each plot, species, dimension (DBH), stage of dieback, stem origin (resprouts after coppicing or from seed), presence of epicormic shoots and subcortical fungi stroma, were recorded for each woody plant.&lt;/p&gt;&lt;p&gt;The plot survey revealed a high frequency of stems classified in a declining stage or dead, on average 42% of the standing stems, with significant differences among the species: 97%, 85%, 74% and 47% for Arbutus unedo, Quercus ilex, Phyllirea latifolia and Fraxinus ornus respectively.&lt;/p&gt;&lt;p&gt;The higher stem mortality of Q. ilex was recorded in the smaller diameter classes, suggesting that the self-thinning process played an important role on the observed mortality as typical in the old not more managed coppices.&lt;/p&gt;&lt;p&gt;To disentangle the role of the interruption of the management from the climatic and biological drivers, time trends on NDVI index were constrained with the duration of the summer dry seasons and comparing our forest with similar Q. ilex forest coppices in the region and regularly managed.&lt;/p&gt;&lt;p&gt;Furthermore, the contribution of recent ambrosia beetles attack was assessed identifying the presence of twigs with signs of previous beetle attack on healthy, declining and dead plants.&lt;/p&gt;&lt;p&gt;Our findings point towards complex tree mortality dynamics, in which the competition generated by the stand abandonment predisposed the forest to the insect attack, leading to the general decline of the forest stand.&lt;/p&gt;

Calcium fertilizers induce soil suppressiveness to Phytophthora cinnamomi root rot of Quercus ilex

2011 ◽  
Vol 132 (2) ◽  
pp. 271-279 ◽  
Author(s):  
María Socorro Serrano ◽  
Paolo De Vita ◽  
Pilar Fernández-Rebollo ◽  
María Esperanza Sánchez Hernández
Keyword(s):  
Root Rot ◽  
Quercus Ilex ◽  
Phytophthora Cinnamomi ◽  
Soil Suppressiveness

The control of Phytophthora root rot of avocado with fungicides and the effect of this disease on water relations, yield and ring neck.

1986 ◽  
Vol 26 (2) ◽  
pp. 249 ◽  
Author(s):  
AW Whiley ◽  
KG Pegg ◽  
JB Saranah ◽  
LI Forsberg
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Water Relations ◽  
Root Rot ◽  
Phytophthora Cinnamomi ◽  
Complete Recovery ◽  
Xylem Water Potential ◽  
Physiological Disorder ◽  
Phytophthora Root Rot ◽  
Water Sprays

Avocado trees (cv. Fuerte) were protected from root rot caused by Phytophthora cinnamomi by foliar metalaxyl. Protected trees had higher xylem water sprays with phosethyl-A1 or soil applications of potentials and showed faster and more complete recovery from water stress during the evening than un treated root rot affected trees. protected trees had greater fruit yields and there was a correlation between the incidence of the physiological disorder ring neck and xylem water potential in trees.

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