scholarly journals Movement of Phytophthora spp. in Maryland's Nursery Trade

Plant Disease ◽  
2014 ◽  
Vol 98 (1) ◽  
pp. 134-144 ◽  
Author(s):  
J. C. Bienapfl ◽  
Y. Balci
Keyword(s):  
West Coast ◽  
Irrigation Water ◽  
Plant Material ◽  
Plant Pathogens ◽  
Morphological Characteristics ◽  
Phytophthora Cactorum ◽  
Main Route ◽  
Phytophthora Spp ◽  
Nursery Practices ◽  
Potting Media

Phytophthora spp. cause major losses in the nursery industry worldwide. However, a clear demonstration of the route of movement has not been previously shown. A survey of 10 Maryland nurseries was conducted over a 3-year period to investigate the presence of Phytophthora spp. on newly arrived plants, mainly from West Coast suppliers. Local nursery plants, irrigation water, and potting media were also sampled for Phytophthora spp. Isolates were identified using a combination of morphological characteristics and DNA sequencing. Species identified included Phytophthora cactorum, P. cambivora, P. cinnamomi, P. citrophthora, P. drechsleri, P. elongata, P. gonapodyides, P. hydropathica, P. irrigata, P. lacustris, P. multivora, P. nicotianae, P. pini, P. plurivora, and P. syringae. P. taxon pgchlamydo was also isolated from irrigation water. Eight of the abovementioned Phytophthora spp. were isolated in association with incoming material, indicating that the movement of these pathogens continues to occur. Asymptomatic plant material was the main route of introduction of Phytophthora spp. to Maryland nurseries. Results also indicated that several Phytophthora spp. could be found in Maryland nurseries in association with infested potting media of asymptomatic plants. Although P. ramorum was not detected, our surveys underscore the significance of nursery practices that allow introductions of these significant plant pathogens to new geographic locations.

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.

PHYTOPHTHORA SPP. IN SOILS OF THE OKANAGAN AND SIMILKAMEEN VALLEYS OF BRITISH COLUMBIA

1964 ◽  
Vol 42 (10) ◽  
pp. 1411-1415 ◽  
Author(s):  
D. L. McIntosh
Keyword(s):  
British Columbia ◽  
Irrigation Water ◽  
Soil Samples ◽  
Phytophthora Cactorum ◽  
Phytophthora Spp ◽  
Orchard Soils ◽  
Chemotactic Effect ◽  
Irrigated Soils ◽  
Cultivated Soils

Phytophthora cactorum is widely distributed in irrigated soils in the Okanagan and Similkameen valleys of British Columbia. Other species isolated, when over 1800 soil samples were assayed for the presence of Phytophthora fungi, were P. cryptogea twice, P. cambivora once, P. megasperma var. sojae once, and P. drechsleri twice. Phytophthora spp. were not recovered from virgin soils nor from non-irrigated cultivated soils, nor from orchard soils receiving irrigation water that is chlorinated. P. cactorum, P. cryptogea, and P. cambivora are pathogenic to rootlets of pear, cherry, apricot, and peach seedlings. P. megasperma var. sojae and P. drechsleri were weakly to non-pathogenic to these hosts. Pear and apple rootlets exerted a chemotactic effect on zoospores of P. cambivora and P. cactorum.

scholarly journals First Record of Leaf Spots on Prunus laurocerasus in Belgium Caused by Phytophthora cactorum and Peronospora sparsa

Plant Disease ◽  
2002 ◽  
Vol 86 (5) ◽  
pp. 563-563 ◽  
Author(s):  
C. Crepel ◽  
S. Inghelbrecht
Keyword(s):  
Plant Pathogens ◽  
Morphological Characteristics ◽  
First Record ◽  
Phytophthora Cactorum ◽  
Centraalbureau Voor ◽  
Leaf Spots ◽  
Agar Plug ◽  
Detached Leaves ◽  
Short Pedicel ◽  
Prunus Laurocerasus

In fall 2000 and 2001, large leaf spots were observed on Prunus laurocerasus. Two different plant pathogens proved to be the cause. Based on morphological characteristics they were identified as Peronospora sparsa (downy mildew) and Phytophthora cactorum. The P. cactorum isolate (CBS 110121) was identified at the Centraalbureau voor Schimmelcultures (Utrecht, the Netherlands). Sporangia were papillate, ovoid, and deciduous, with a short pedicel. The isolate was homothallic. Chlamydospores were present and approximately 40 μm in diameter. Oogonia were 25 to 31 μm in diameter, and the antheridia were paragynous. Peronospora sparsa had been reported to infect Prunus laurocerasus in the United Kingdom (1). In Belgium, cv. Etna was very susceptible, but cvs. Rotundifolia and Marbled White were also infected. Rotundifolia was susceptible to P. cactorum. At first inspection, the two pathogens caused similar leaf symptoms: large, irregular, brown, necrotic spots on the tips, margins, and center of leaves. However, the undersides of leaves infected with Peronospora sparsa were covered with typical gray mycelium, which was absent on leaves infected with P. cactorum. P. cactorum caused concentric circles in the brown spots. Leaf spots caused by P. cactorum developed quickly in a moist chamber. Spots caused by Peronospora sparsa did not enlarge significantly on detached leaves, but in the field it caused serious losses within a few days. To prove the pathogenicity of P. cactorum, Koch's postulates were satisified on five Prunus laurocerasus Etna plants. The fungus was grown on corn meal agar for 1 week until sporangia formed. An agar plug was placed on five wounded leaves per plant and sealed with Parafilm. Inoculated plants were kept under a plastic cover for 1 day at 22°C, then the cover was removed, and the plants were kept at 20°C. Symptom development was visible after 3 days, and P. cactorum was successfully reisolated. This is the first record of P. cactorum and Peronospora sparsa leaf infection on Prunus laurocerasus in Belgium. Reference: (1) G. Hall et al. Plant Pathol. 41:224, 1992.

Applying Phytophthora ramorum Inoculum to Hosts: A New Method That Simulates Overhead Irrigation

2015 ◽  
Vol 16 (2) ◽  
pp. 100-106 ◽  
Author(s):  
Lucy Rollins ◽  
Marianne Elliott ◽  
Gary Chastagner
Keyword(s):  
Regression Analysis ◽  
Irrigation Water ◽  
Plant Material ◽  
Phytophthora Ramorum ◽  
New Method ◽  
Regulatory Agencies ◽  
Laboratory Conditions ◽  
Phytophthora Spp ◽  
Overhead Irrigation ◽  
Property Owners

The inoculum threshold for Phytophthora ramorum in irrigation water required for infection of plant material was investigated using a novel pressurized device designed to deliver zoospore inoculum in a way that simulated certain aspects of overhead irrigation. The measured-inoculum spray applicator (MISA) was made from plastic plumbing parts and worked by spraying measured volumes of pressurized zoospore inoculum onto plant material through an adjustable misting nozzle attached to the bottom of the device. Pressurization and spraying of P. ramorum zoospores through the MISA did not significantly affect zoospore viability or infectivity on wounded and non-wounded detached Rhododendron x ‘Nova Zembla’ leaves under controlled laboratory conditions. An inoculum threshold of 51 zoospores/ml was found for infection of Rhododendron leaves by P. ramorum using regression analysis. The MISA can potentially be used to simulate overhead irrigation in research involving pathogenic Phytophthora spp., and the results of the current research may assist nursery managers, property owners, and regulatory agencies in assessing the risk of using P. ramorum infested water for irrigation within nurseries and private landscapes. Accepted for publication 19 June 2015. Published 26 June 2015.

Phytophthora Community Structure Analyses in Oregon Nurseries Inform Systems Approaches to Disease Management

2014 ◽  
Vol 104 (10) ◽  
pp. 1052-1062 ◽  
Author(s):  
Jennifer L. Parke ◽  
Brian J. Knaus ◽  
Valerie J. Fieland ◽  
Carrie Lewis ◽  
Niklaus J. Grünwald
Keyword(s):  
Community Structure ◽  
Plant Pathogens ◽  
Systems Approach ◽  
Production Cycle ◽  
Systems Approaches ◽  
Phytophthora Spp ◽  
Critical Control Points ◽  
Nursery Production ◽  
Production Stages ◽  
Potting Media

Nursery plants are important vectors for plant pathogens. Understanding what pathogens occur in nurseries in different production stages can be useful to the development of integrated systems approaches. Four horticultural nurseries in Oregon were sampled every 2 months for 4 years to determine the identity and community structure of Phytophthora spp. associated with different sources and stages in the nursery production cycle. Plants, potting media, used containers, water, greenhouse soil, and container yard substrates were systematically sampled from propagation to the field. From 674 Phytophthora isolates recovered, 28 different species or taxa were identified. The most commonly isolated species from plants were Phytophthora plurivora (33%), P. cinnamomi (26%), P. syringae (19%), and P. citrophthora (11%). From soil and gravel substrates, P. plurivora accounted for 25% of the isolates, with P. taxon Pgchlamydo, P. cryptogea, and P. cinnamomi accounting for 18, 17, and 15%, respectively. Five species (P. plurivora, P. syringae, P. taxon Pgchlamydo, P. gonapodyides, and P. cryptogea) were found in all nurseries. The greatest diversity of taxa occurred in irrigation water reservoirs (20 taxa), with the majority of isolates belonging to internal transcribed spacer clade 6, typically including aquatic opportunists. Nurseries differed in composition of Phytophthora communities across years, seasons, and source within the nursery. These findings suggest likely contamination hazards and target critical control points for management of Phytophthora disease using a systems approach.

scholarly journals Efficacy of Chlorine in Controlling Five Common Plant Pathogens

HortScience ◽  
2009 ◽  
Vol 44 (1) ◽  
pp. 157-163 ◽  
Author(s):  
Diane Feliciano Cayanan ◽  
Ping Zhang ◽  
Weizhong Liu ◽  
Mike Dixon ◽  
Youbin Zheng
Keyword(s):  
Irrigation Water ◽  
Contact Time ◽  
Plant Pathogens ◽  
Free Chlorine ◽  
Phytophthora Cactorum ◽  
Economical Method ◽  
The Common ◽  
Time Required ◽  
Common Plant ◽  
Critical Contact

Recycled irrigation water is one of the major sources of inoculum and may spread plant pathogens throughout the nursery or greenhouse operation. Chlorination is the most economical method of disinfecting water and has been adopted by some North American commercial growers. However, chlorine has not been assessed as a disinfectant for the common plant pathogens Phytophthora infestans, Phytophthora cactorum, Pythium aphanidermatum, Fusarium oxysporum, and Rhizoctonia solani. These pathogens were exposed to five different initially free chlorine solution concentrations ranging from 0.3 to 14 mg·L−1 in combination with five contact times of 0.5, 1.5, 3, 6, and 10 min to determine the free chlorine threshold and critical contact time required to kill each pathogen. Results indicated that the free chlorine threshold and critical contact time for control of P. infestans, P. cactorum, P. aphanidermatum, F. oxysporum, and R. solani were 1, 0.3, 2, 14, and 12 mg·L−1 for 3, 6, 3, 6, and 10 min, respectively.

scholarly journals Phytophthora Populations in Nursery Irrigation Water in Relationship to Pathogenicity and Infection Frequency of Rhododendron and Pieris

Plant Disease ◽  
2014 ◽  
Vol 98 (9) ◽  
pp. 1213-1220 ◽  
Author(s):  
A. L. Loyd ◽  
D. M. Benson ◽  
K. L. Ivors
Keyword(s):  
Irrigation Water ◽  
Root Rot ◽  
Plant Pathogens ◽  
Primary Source ◽  
Infection Frequency ◽  
Growing Seasons ◽  
Source Of Infection ◽  
Phytophthora Spp ◽  
Trap Plants ◽  
Foliar Pathogens

Phytophthora spp. are waterborne plant pathogens that are commonly found in streams, rivers, and reclaimed irrigation water. Rhododendron and Pieris trap plants at two commercial nurseries were irrigated with water naturally infested with Phytophthora spp. during the 2011 and 2012 growing seasons to assess the frequency of disease. Phytophthora spp. were consistently recovered from water samples at every collection time but detected on only 2 of the 384 trap plants during the two growing seasons. Pathogenicity assays proved that Phytophthora hydropathica and Phytophthora taxon PgChlamydo, commonly recovered taxa in irrigation water at the nurseries, were foliar pathogens of Rhododendron and Pieris; however, neither species was able to cause root rot on these same hosts. Overall, Phytophthora spp.-infested irrigation water did not act as a primary source of infection on Rhododendron and Pieris, even though foliar pathogenic species of Phytophthora were present in the water.

scholarly journals A taxonomic review of pterotracheoid gastropod mollusks from California Current waters off the west coast of North America

Zoosymposia ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 147-150
Author(s):  
ROGER R. SEAPY
Keyword(s):  
North America ◽  
West Coast ◽  
Morphological Characteristics ◽  
California Current ◽  
Single Species ◽  
The West ◽  
Taxonomic Review ◽  
Gastropod Mollusks ◽  
Taxonomic Characterization

Taxonomic characterization of pterotracheoid gastropods, morphological characteristics and occurrence in California Current waters are reviewed. Single species of atlantid (Atlanta californiensis) and carinariid (Carinaria japonica) from these waters are described and illustrated.

scholarly journals Fungi and Oomycetes in the Irrigation Water of Forest Nurseries

Forests ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 459 ◽  
Author(s):  
Adas Marčiulynas ◽  
Diana Marčiulynienė ◽  
Jūratė Lynikienė ◽  
Artūras Gedminas ◽  
Miglė Vaičiukynė ◽  
...  
Keyword(s):  
Irrigation Water ◽  
Plant Pathogens ◽  
High Throughput Sequencing ◽  
Irrigation System ◽  
Tree Seedlings ◽  
High Quality ◽  
Forest Nurseries ◽  
Study Sites ◽  
Microbial Samples

The aim of the present study was to assess fungal and oomycete communities in the irrigation water of forest nurseries, focusing on plant pathogens in the hope of getting a better understanding of potential pathogenic microorganisms and spreading routes in forest nurseries. The study sites were at Anykščiai, Dubrava, Kretinga and Trakai state forest nurseries in Lithuania. For the collection of microbial samples, at each nursery five 100-L water samples were collected from the irrigation ponds and filtered. Following DNA isolation from the irrigation water filtrate samples, these were individually amplified using ITS rDNA as a marker and subjected to PacBio high-throughput sequencing. Clustering in the SCATA pipeline and the taxonomic classification of 24,006 high-quality reads showed the presence of 1286 non-singleton taxa. Among those, 895 were representing fungi and oomycetes. The detected fungi were 57.3% Ascomycota, 38.1% Basidiomycota, 3.1% Chytridiomycota, 0.8% Mucoromycota and 0.7% Oomycota. The most common fungi were Malassezia restricta E. Guého, J. Guillot & Midgley (20.1% of all high-quality fungal sequences), Pezizella discreta (P. Karst.) Dennis (10.8%) and Epicoccum nigrum Link (4.9%). The most common oomycetes were Phytopythium cf. citrinum (B. Paul) Abad, de Cock, Bala, Robideau, Lodhi & Lévesque (0.4%), Phytophthora gallica T. Jung & J. Nechwatal (0.05%) and Peronospora sp. 4248_322 (0.05%). The results demonstrated that the irrigation water used by forest nurseries was inhabited by a species-rich but largely site-specific communities of fungi. Plant pathogens were relatively rare, but, under suitable conditions, these can develop rapidly, spread efficiently through the irrigation system and be a threat to the production of high-quality tree seedlings.

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