scholarly journals First Confirmation of Phytophthora quercina on Oaks in Asia

Plant Disease ◽  
2002 ◽  
Vol 86 (4) ◽  
pp. 442-442 ◽  
Author(s):  
Y. Balci ◽  
E. Halmschlager
Keyword(s):  
Growth Rate ◽  
Tree Mortality ◽  
Morphological Characteristics ◽  
Phytophthora Species ◽  
Infested Soil ◽  
Mature Trees ◽  
Main Trunk ◽  
Soil P ◽  
Phytophthora Spp ◽  
Individual Trees

During surveys of forests in the Asian Region of Turkey in 1999, 2000, and 2001, mature trees of several oak species were observed to have symptoms of decline, including thinning of the crown, yellowing and wilting of leaves, dieback of branches, and growth of epicormic shoots on branches and the main trunk. Observations over time confirmed a slow progress of tree mortality. To isolate Phytophthora spp. that might be associated with the decline, samples of rhizosphere soil including fine roots with necrotic lesions, were collected from around the bases of individual trees. Young leaflets from Quercus robur, Q. petraea, and Q. hartwissiana were used in a bioassay to bait flooded soil subsamples. After 3 to 5 days, baits were transferred to plates of PARPNH, a medium selective for Phytophthora spp. (1). Phytophthora spp. were recovered from 38 of 51 sites investigated (75%). In all, 10 species of Phytophthora were isolated; P. quercina was detected most frequently and was obtained from 29 (57%) sampled sites. Identification of isolates of P. quercina was based on comparisons of cultural and morphological characteristics to the description of the holotype (2) and to authentic cultures. Slight differences from the description of the holotype were observed for the size of sporangia, oogonia, and chlamydospores. On V8 agar most of the colonies showed an optimal radial growth at 22.5°C, with a growth rate ranging from 4.5 to 5.6 mm per day. Isolates from Turkey showed a lower optimal temperature and a higher growth rate compared with European strains. Recent studies have shown that many Phytophthora species, including P. quercina, occur in declining oak stands in Europe. In pathogenicity tests of infested soil, P. quercina isolates proved to be one of the more pathogenic species to roots of young Q. robur plants (2). Previously, P. quercina was only found in Europe. New hosts species for P. quercina include Q. hartwissiana, Q. frainetto, and the endemic species Q. vulcanica. Observations suggest that P. quercina is widespread in Turkey and occurs within the natural range of oak, which raises the question of the role of P. quercina in the oak decline syndrome. References: (1) T. Jung et al. Eur. J. For. Pathol. 26:253, 1996. (2) T. Jung et al. Mycol. Res. 103:785, 1999.

scholarly journals Phytophthora Root and Collar Rot of Paulownia, a New Disease for Europe

Forests ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1664
Author(s):  
Francesco Aloi ◽  
Mario Riolo ◽  
Federico La Spada ◽  
Gaetano Bentivenga ◽  
Salvatore Moricca ◽  
...  
Keyword(s):  
Irrigation Management ◽  
Morphological Characteristics ◽  
Stem Bark ◽  
Phytophthora Species ◽  
Crown Rot ◽  
Infested Soil ◽  
Soil P ◽  
Rdna Its ◽  
Rdna Its Sequences ◽  
Root And Crown Rot

Paulownia species are fast growing trees native to China, which are being grown in managed plantings in several European countries for the production of wood and biomasses. In 2018, wilting, stunting, leaf yellowing, and collapse, as a consequence of root and crown rot, were observed in around 40% of trees of a 2-year-old planting of Paulownia elongata × P. fortunei in Calabria (Southern Italy). Two species of Phytophthora were consistently recovered from roots, basal stem bark, and rhizosphere soil of symptomatic trees and were identified as Ph. nicotianae and Ph. palmivora on the basis of both morphological characteristics and phylogenetic analysis of rDNA ITS sequences. Koch’s postulates were fulfilled by reproducing the symptoms on potted paulownia saplings transplanted into infested soil or stem-inoculated by wounding. Both Phytophthora species were pathogenic and caused root rot and stem cankers. Even though P. palmivora was the only species recovered from roots of naturally infected plants, in pathogenicity tests through infested soil P. nicotianae was more virulent. This is the first report of Phytophthora root and crown rot of a Paulownia species in Europe. Strategies to prevent this emerging disease include the use of healthy nursery plants, choice of well-drained soils for new plantations, and proper irrigation management.

scholarly journals Illustration of Key Morphological Characteristics of Phytophthora Species Identified in Virginia Nursery Irrigation Water

2006 ◽  
Vol 7 (1) ◽  
pp. 41 ◽  
Author(s):  
Elizabeth A. Bush ◽  
Erik L. Stromberg ◽  
Chuanxue Hong ◽  
Patricia A. Richardson ◽  
Ping Kong
Keyword(s):  
Irrigation Water ◽  
Ornamental Plants ◽  
Morphological Characteristics ◽  
Phytophthora Species ◽  
Molecular Methods ◽  
Morphological Identification ◽  
Taxonomic Identification ◽  
Effluent Water ◽  
Phytophthora Spp ◽  
Diagnostic Characteristics

Phytophthora diseases are commonly diagnosed on ornamental plants, but taxonomic identification to species can be intimidating. This illustrative guide is designed to aid diagnosticians in morphological identification of certain Phytophthora spp. that have been reported in irrigation and effluent water in nurseries. Using both morphological and molecular methods, the authors identify diagnostic characteristics that are consistent and easy to use. Accepted for publication 6 April 2006. Published 21 June 2006.

scholarly journals Phytophthora plurivora T. Jung & T. I. Burgess and other Phytophthora species causing important diseases of ericaceous plants in the Czech Republic

2011 ◽  
Vol 47 (No. 1) ◽  
pp. 13-19 ◽  
Author(s):  
M. Mrázková ◽  
K. Černý ◽  
M. Tomšovský ◽  
V. Strnadová
Keyword(s):  
Czech Republic ◽  
Dna Sequences ◽  
Morphological Characteristics ◽  
Common Species ◽  
Phytophthora Species ◽  
Natural Ecosystems ◽  
The Czech Republic ◽  
Urban Greenery ◽  
Phytophthora Spp ◽  
Shoot Blight

Ornamental nurseries, garden centres, public gardens and urban greenery in the Czech Republic were surveyed in 2006–2009 for the presence of Phytophthora spp. and the diseases they cause on ericaceous plants. Diseased plants such as Rhododendron spp., Pieris floribunda, Vaccinium sp., and Azalea sp. showed various symptoms including leaf spot, shoot blight, twig lesions or stem, root and collar rot. Nearly 140 Phytophthora isolates were collected from symptomatic plants in different areas of the country. Of the Phytophthora spp. on ericaceous plants or in their surroundings, P. plurivora appeared to be the most common species. Herein, we focus on the most frequently occurring species, P. plurivora, and describe its morpho-physiological and pathogenicity features and confirm its identity based on ITS sequences of rDNA. In addition, we give a list of other Phytophthora spp. including P. cactorum, P. cambivora, P. cinnamomi, P. citrophthora, P. megasperma, P. multivora, P. ramorum, and P. gonapodyides that we identified on the basis of their cultural and morphological characteristics and DNA sequences. We also discuss their importance in cultivated and natural ecosystems.

scholarly journals Phytophthora Diversity in Pennsylvania Nurseries and Greenhouses Inferred from Clinical Samples Collected over Four Decades

2020 ◽  
Vol 8 (7) ◽  
pp. 1056
Author(s):  
Cody Molnar ◽  
Ekaterina Nikolaeva ◽  
Seonghwan Kim ◽  
Tracey Olson ◽  
Devin Bily ◽  
...  
Keyword(s):  
Plant Species ◽  
Morphological Characteristics ◽  
Phytophthora Species ◽  
Clinical Samples ◽  
Department Of Agriculture ◽  
Distinct Subgroup ◽  
Exotic Pathogens ◽  
Diverse Plant Species ◽  
Insight Into ◽  
Diverse Plant

The increasing movement of exotic pathogens calls for systematic surveillance so that newly introduced pathogens can be recognized and dealt with early. A resource crucial for recognizing such pathogens is knowledge about the spatial and temporal diversity of endemic pathogens. Here, we report an effort to build this resource for Pennsylvania (PA) by characterizing the identity and distribution of Phytophthora species isolated from diverse plant species in PA nurseries and greenhouses. We identified 1137 Phytophthora isolates cultured from clinical samples of >150 plant species submitted to the PA Department of Agriculture for diagnosis from 1975 to 2019 using sequences of one or more loci and morphological characteristics. The three most commonly received plants were Abies, Rhododendron, and Pseudotsuga. Thirty-six Phytophthora species identified represent all clades, except 3 and 10, and included a distinct subgroup of a known species and a prospective new species. Prominent pathogenic species such as P. cactorum, P. cinnamomi, P. nicotianae, P. drechsleri, P. pini, P. plurivora, and P. sp. kelmania have been found consistently since 1975. One isolate cultured from Juniperus horizontalis roots did not correspond to any known species, and several other isolates also show considerable genetic variation from any authentic species or isolate. Some species were isolated from never-before-documented plants, suggesting that their host range is larger than previously thought. This survey only provides a coarse picture of historical patterns of Phytophthora encounters in PA nurseries and greenhouses because the isolation of Phytophthora was not designed for a systematic survey. However, its extensive temporal and plant coverage offers a unique insight into the association of Phytophthora with diverse plants in nurseries and greenhouses.

The digestibility and the nitrogen, phosphorus and ash contents of the leaves of some Australian trees and shrubs

1973 ◽  
Vol 13 (62) ◽  
pp. 245 ◽  
Author(s):  
MN McLeod
Keyword(s):  
Significant Variation ◽  
Dry Matter ◽  
Mature Trees ◽  
Lower Range ◽  
Nitrogen Levels ◽  
Dry Matter Digestibility ◽  
Individual Trees ◽  
Trees And Shrubs ◽  
Nitrogen Phosphorus

The dry matter digestibility measured in vitro and the levels of nitrogen, phosphorus and ash were determined on the leaves from mature trees of twenty-one species growing in two arboreta in southeastern Queensland and known to be grazed by animals. Most of the leaf samples had digestibilities in the lower range (68 per cent samples < 50 per cent D.M.D.) and low ash levels (65 per cent samples < 7 per cent ash). Nitrogen levels were satisfactory (86 per cent samples in range 1.5-3.0 per cent N) but the level of phosphorus tended to be low (84 per cent samples < 0.20 per cent P). Statistically significant variation between individual trees and seasons was found with some species.

scholarly journals Sudden Phytophthora Dieback of Wild Cherry Trees in Northwest Hungary

2016 ◽  
Vol 12 (2) ◽  
pp. 117-124
Author(s):  
Judit Sárándi-Kovács ◽  
László Nagy ◽  
Ferenc Lakatos ◽  
György Sipos
Keyword(s):  
Prunus Avium ◽  
Deciduous Forest ◽  
Flood Plain ◽  
Phytophthora Species ◽  
Soil Conditions ◽  
Wild Cherry ◽  
Plain Area ◽  
Phytophthora Spp ◽  
Mixed Deciduous Forest ◽  
Cherry Trees

Abstract During a regular survey of declining forests in 2011, sudden dieback symptoms were observed on scattered wild cherry trees (Prunus avium) in a mixed deciduous forest stand, located in the flood plain area of the Rába River, in northwest Hungary. In this study, we correlated both soil conditions and presence of Phytophthora spp. to dieback of cherry trees. Two Phytophthora species, P. polonica and P. plurivora, were isolated from the rhizosphere soil of the dying trees. By contrast, only P. polonica was recovered from the necrotic tissues of symptomatic roots. Stem and root inoculation tests on cherry seedlings showed pathogenicity of both species, although P. polonica proved to be more virulent. This is the first report of natural infections of P. polonica.

Encasement in plant morphology: an integrative approach from genes to organisms

2005 ◽  
Vol 83 (10) ◽  
pp. 1207-1221 ◽  
Author(s):  
Christian Lacroix ◽  
Bernard Jeune ◽  
Denis Barabé
Keyword(s):  
Growth Rate ◽  
Morphological Characteristics ◽  
Plant Morphology ◽  
Integrative Approach ◽  
Structural Level ◽  
Classical Approach ◽  
Developmental Genes ◽  
Qualitative And Quantitative ◽  
New Concepts ◽  
Dynamic Morphology

Recent advances in molecular genetics are prompting developmental plant morphologists to refine the theoretical context of their field. For example, at the level of the action of certain developmental genes, the distinction between recognized structural categories (i.e., stem and leaf) are not obvious. This issue has also been analyzed by morphologists from qualitative and quantitative perspectives and has lead to similar conclusions. Consequently, the classical approach to morphology with a typological view of organ categories is no longer sufficient to explain the set of all possible forms. However, within the context of a dynamic morphology, where processes of development such as growth rate, duration, and distribution are considered, a more encompassing view of the generation of form can be achieved. We therefore propose that classical morphology is a subset of dynamic morphology. The main goal of this paper is to show how new concepts and methods of viewing plant morphology allow us to build a conceptual theoretical framework that may have a predictive value with respect to morphological characteristics as well as molecular properties of organs. The main premise of this commentary, within the context of dynamic morphology, is that the plant consists of an encasement of structures or a nesting of partially similar units. Common developmental processes are in operation at each structural level and variations in the modalities of these processes lead to the development of specific structures. Repeating polymorphic sets (RPS) represent an extension of this perspective on plant development and have the potential to predict the existence of new, perhaps unknown forms. The idea of repeating polymorphic sets can also be extended to outline the activity of specific developmental genes to explain how a wide variety of those genes are interrelated during development to specify form.

Detection of oomycide-insensitive Phytophthora isolates in Maryland ornamental nurseries and Mid-Atlantic landscapes provide data for reconsidering management strategies

2021 ◽  
Author(s):  
Justine Beaulieu ◽  
Johanna Del Castillo Munera ◽  
Yilmaz Balci
Keyword(s):  
Growth Rate ◽  
Mycelial Growth ◽  
Management Strategies ◽  
Resistance Management ◽  
Phytophthora Species ◽  
Oak Forests ◽  
Relative Growth ◽  
Off Label ◽  
Potting Media ◽  
Almost All

Five Phytophthora species comprising a total of 243 isolates (77 P. cinnamomi, 23 P. citrophthora, 18 P. multivora, 18 P. pini, and 107 P. plurivora) were screened for sensitivity to mefenoxam, fosetyl-Al, dimethomorph, dimethomorph + ametoctradin and fluoxastrobin using amended agar assays. Mefenoxam-insensitive isolates were detected within P. cinnamomi (4%), P. multivora (11%), and P. plurivora (12%) even at approximately 2.5x the recommended label rate. These isolates were also insensitive to higher (off-label) concentrations of fluoxastrobin. Concentrations of dimethomorph (400 g/mL) and dimethomorph + ametoctradin (100 g/mL) were mostly effective in mycelial growth inhibition, but two P. plurivora isolates were insensitive, suggesting that resistance management is required. All mefenoxam-insensitive isolates were sensitive to fosetyl-Al at the label rate. Surprisingly, the populations of P. cinnamomi from mid-Atlantic oak forests included insensitive isolates. With almost all species, isolates recovered from asymptomatic hosts (e.g., soil/potting media collected of randomly selected asymptomatic hosts) had a significantly greater relative growth rate when compared to isolates recovered from symptomatic hosts (e.g., isolates recovered from lesions or wilted plants). These findings suggest that mefenoxam should no longer be used to manage oomycetes in Maryland ornamental nurseries and that the use of fluoxastrobin should be limited.

Temperature-Growth Relations and Genetic Diversity of A2 Mating-Type Isolates of Phytophthora cinnamomi in Australia

1974 ◽  
Vol 22 (2) ◽  
pp. 231 ◽  
Author(s):  
CJ Shepherd ◽  
BH Pratt
Keyword(s):  
Growth Rate ◽  
First Generation ◽  
Phytophthora Cinnamomi ◽  
Phytophthora Species ◽  
Temperature Growth ◽  
Field Isolates ◽  
Place Of Origin ◽  
Successive Generations ◽  
Cardinal Temperatures ◽  
Range Of Values

Determinations of cardinal temperatures for growth on various media of 50 Australian isolates of Phytophthova cinnamomi showed that growth did not occur outside the range 5-35°C. The range of temperatures at which growth optima occurred varied according to the isolate and medium used and encompassed the whole range of values reported by overseas authors. Growth rates of 361 isolates on corn meal agar at 25°C varied within the range 4.7-10.5 mm/day. There was no correlation between optimum temperature and whether isolates were slow- or fastgrowing or their place of origin. Fast-growing isolates (6-11 mm/day) were obtained from all States, but slower-growing isolates (<6 mm/day) were obtained only from southern and western regions of Australia. Populations from different regions of Australia exhibited different growth rate parameters. The variability of mycelial isolates in culture was studied by examining differences in growth rate among replicated parent, single-zoospore, single-zoosporangium and single terminal-hyphal isolates. Extensive variation was found among first generation single-zoospore progenies of field isolates, with lesser variation among progeny of single zoosporangia, terminal hyphal cultures and second and third generation zoospore derivatives. The origin of this variation is discussed and it is suggested that field isolates are heterokaryotic, since zoospores proved to be predominantly uninucleate. When various Phytophthora species were incubated at temperatures above those at which growth was possible and then returned to 25°C, their subsequent ability to resume growth depended on the particular time-temperature combination used. Considerable variation of response was found among a number of isolates of P. cinnamomi and, following the establishment of single zoospore isolates, the potential variability of field isolates was shown to persist through successive generations of zoospore propagation. It is suggested that a cytoplasmic mechanism of inheritance may be responsible for this variation.

scholarly journals A new species of Coccoloba P. Browne (Polygonaceae) from the Brazilian Amazon with exceptionally large leaves

2019 ◽  
Vol 49 (4) ◽  
pp. 324-329 ◽  
Author(s):  
Efigenia de MELO ◽  
Carlos Alberto CID FERREIRA ◽  
Rogério GRIBEL
Keyword(s):  
New Species ◽  
Conservation Status ◽  
Natural Habitat ◽  
Morphological Characteristics ◽  
Brazilian Amazon ◽  
Cultivated Plants ◽  
New Taxon ◽  
Madeira River ◽  
Individual Trees ◽  
A New Species

ABSTRACT We describe and illustrate a new species of Coccoloba (Polygonaceae), named Coccoloba gigantifolia, from the Brazilian Amazon. It resembles Coccoloba mollis Casar, but differs from the latter species by its much larger leaves in the fertile branches. The species has only been recorded in the Madeira River basin, in the states of Amazonas and Rondônia, in the central and southwestern Brazilian Amazon. The description was based on herbarium material, cultivated plants, and individual trees in their natural habitat. We provide illustrations, photographs, and an identification key with morphological characteristics that distinguish the new taxon from the other two related taxa of the Coccoloba sect. Paniculatae, as well as comments on the geographic distribution and conservation status of the species.

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