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D M Benson - One of the best experts on this subject based on the ideXlab platform.
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Host Specificity and Variations in Aggressiveness of North Carolina Isolates of Phytophthora cryptogea and P. drechsleri in Greenhouse Ornamental Plants.
Plant Disease, 2020Co-Authors: H A Olson, D M BensonAbstract:Abstract Three isolates of Phytophthora cryptogea and three isolates of P. drechsleri were evaluated for host specificity and variations in aggressiveness on eight Floriculture Crops commonly grown in North Carolina. Plants were monitored for the development of foliar symptoms stemming from root rot caused by Phytophthora. No isolates of P. cryptogea or P. drechsleri had the same host range, though all P. cryptogea isolates caused foliar symptoms on gerbera daisy and annual stock, and all P. drechsleri isolates incited disease on osteospermum. No African marigold plants developed foliar symptoms of Phytophthora root rot. All P. cryptogea isolates caused foliar symptoms on at least three tested plant species. Isolates of P. drechsleri varied from highly specific and only causing disease on a single host species to relatively nonspecific and causing foliar symptoms on the majority of host plants. This is the first report of host specificity of ornamental isolates of P. drechsleri, and several of the tested ...
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phylogenetic history of phytophthora cryptogea and p drechsleri isolates from Floriculture Crops in north carolina greenhouses
Phytopathology, 2011Co-Authors: H A Olson, Ignazio Carbone, D M BensonAbstract:ABSTRACT The evolutionary history of Phytophthora cryptogea and P. drechsleri isolates previously collected from Floriculture Crops in North Carolina commercial greenhouses was explored with coalescent- and parsimony-based analyses. Initially, 68 isolates representing 13 location–host groups were sequenced at multiple loci. Sequences of all isolates within a group were identical. A subset of isolates were selected, cloned to resolve heterozygous sites, and analyzed with SNAP Workbench. The internal transcribed spacer (ITS) region of the ribosomal DNA and cytochrome oxidase II gene genealogies were congruent and indicated that P. cryptogea and P. drechsleri are sister species diverged from a common ancestor with no evidence of gene flow. In contrast, genealogies inferred from β-tubulin (β-tub) and translation elongation factor 1α (EF-1α) genes were in conflict with these loci. Coalescent analysis based on a nonrecombining partition in β-tub and EF-1α showed an initial (older) split between P. cryptogea and...
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characterization of phytophthora spp on Floriculture Crops in north carolina
Plant Disease, 2011Co-Authors: H A Olson, D M BensonAbstract:Abstract Isolates of Phytophthora in Floriculture Crops were collected from North Carolina commercial greenhouse facilities in 2007 and 2008, identified, and characterized for mating type and mefenoxam sensitivity. In all, 163 isolates from 13 host species at 11 locations were identified primarily as Phytophthora nicotianae (59%), P. drechsleri (23%), P. cryptogea (9%), and P. tropicalis (4%). Multiple Phytophthora spp. were found at five locations. DNA sequencing was more reliable for differentiating P. cryptogea and P. drechsleri. Only the A1 mating type of P. drechsleri was collected; however, both mating types of P. nicotianae, P. cryptogea, and P. tropicalis were found. Overall, 66% of Phytophthora isolates were resistant or intermediate in resistance to mefenoxam at 1 μg a.i./ml. Three groups of P. drechsleri isolates had effective concentration of mefenoxam providing 50% growth inhibition (EC50) estimates over 700 μg a.i./ml. EC50 estimates for P. nicotianae ranged from 246 to 435 μg a.i./ml. Isola...
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identification mefenoxam sensitivity and compatibility type of phytophthora spp attacking Floriculture Crops in north carolina
Plant Disease, 2005Co-Authors: J Hwang, D M BensonAbstract:ABSTRACT Phytophthora isolates were collected from Floriculture Crops grown in commercial greenhouses in North Carolina for species identification, compatibility type determination, and mefenoxam sensitivity tests. Isolation from 41 symptomatic plant species at 29 production locations resulted in 483 isolates from eight Crops at seven locations. Phytophthora cryptogea (184 isolates) was recovered from dusty miller and gerbera daisy. All isolates of P. cryptogea were insensitive or intermediate in sensitivity to mefenoxam at 1 μg a.i./ml and were A1 compatibility type. P. nicotianae (273 isolates) was isolated from African violet, lavender, pansy, petunia, and vinca. Of these isolates, 21% were insensitive to mefenoxam at either 1 or 100 μg a.i./ml. Isolates of P. nicotianae from five locations were A2 compatibility type, whereas isolates on pansy at one location were A1 compatibility type. English ivy grown at two locations was infected with P. palmivora. All 26 isolates of P. palmivora were sensitive to ...
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etiology of phytophthora drechsleri and p nicotianae p parasitica diseases affecting Floriculture Crops
Plant Disease, 2003Co-Authors: Kurt Lamour, D M Benson, J Hwang, Margery L Daughtrey, M K HausbeckAbstract:Lamour, K. H., Daughtrey, M. L., Benson, D. M., Hwang, J., and Hausbeck, M. K. 2003. Etiology of Phytophthora drechsleri and P. nicotianae (=P. parasitica) diseases affecting Floriculture Crops. Plant Dis. 87:854-858. Phytophthora nicotianae and P. drechsleri isolates (n = 413) recovered from eight floricultural hosts at 11 different production sites were described according to compatibility type, resistance to mefenoxam, and amplified fragment length polymorphism (AFLP) profiles. Sample sizes ranged from 2 to 120. In all cases, isolates recovered from a single facility had the same compatibility type and resistance to mefenoxam. AFLP analysis indicated that six clonal lineages of P. nicotianae and two clonal lineages of P. drechsleri were responsible for the 11 epidemics and that isolates recovered from the same facility were identical. A single clone of P. nicotianae was recovered from snapdragons at two field production sites in the southeastern United States receiving seedlings from the same source. This clone persisted at one site from 2000 to 2001. Another clone was recovered from verbena at three separate greenhouse facilities where one facility was supplying verbena to the other two. These results suggest that asexual reproduction of these pathogens plays an important role in epidemics and spread may occur between distant facilities via movement of plants.
Mary K. Hausbeck - One of the best experts on this subject based on the ideXlab platform.
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Rapid Sand Filtration of Recycled Irrigation Water Controlled Pythium Root Rot of Poinsettia in Greenhouse
Horttechnology, 2019Co-Authors: Sangho Jeon, Mary K. Hausbeck, Charles S. Krasnow, Gemini D. Bhalsod, Blair R. Harlan, Steven I. Safferman, Wei ZhangAbstract:Pythium species incite crown and root rot and can be highly destructive to Floriculture Crops in greenhouses, especially when irrigation water is recycled. This study assessed the performance of rapid filtration of recycled irrigation water for controlling pythium root rot of poinsettia (Euphorbia pulcherrima) in greenhouses. Two greenhouse experiments investigated the effect of filter media type (sand and activated carbon), fungicide application (etridiazole), and pathogen inoculum source (infested growing media and infested irrigation water). Rapid sand filtration consistently controlled pythium root rot of poinsettia. Significant improvements in height, weight, root rot severity, and horticultural quality were observed for the plants in the sand filter treatment, compared with the inoculated control plants. However, the activated carbon filter removed essential nutrients from the irrigation water, resulting in plant nutrient deficiency and consequently leaf chlorosis, thus reducing plant weight, height, and horticultural quality. The etridiazole application did not completely prevent root infection by Pythium aphanidermatum, but plant weight, height, and horticultural quality were not negatively affected. P. aphanidermatum spread from infested growing media to healthy plants when irrigation water was recycled without filtration. Rapid sand filtration appears to have the potential to limit the spread of P. aphanidermatum that causes root rot of greenhouse Floriculture Crops.
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population structure of pythium ultimum from greenhouse floral Crops in michigan
Plant Disease, 2019Co-Authors: Johanna Del Castillo Munera, L M Quesadaocampo, Alejandro Rojas, Martin I Chilvers, Mary K. HausbeckAbstract:: Pythium ultimum causes seedling damping-off and root and crown rot in greenhouse ornamental plants. To understand the population dynamics and assess population structure of P. ultimum in Michigan Floriculture Crops, simple sequence repeats (SSRs) were developed using the previously published P. ultimum predicted transcriptome. A total of 166 isolates sampled from 2011 to 2013 from five, one, and three greenhouses in Kalamazoo, Kent, and Wayne Counties, respectively, were analyzed using six polymorphic and fluorescently labeled SSR markers. The average unbiased Simpson's index (λu, 0.95), evenness (E5, 0.56), and recovery of 12 major clones out of the 65 multilocus genotypes obtained, suggests that P. ultimum is not a recent introduction into Michigan greenhouses. Analyses revealed a clonal population, with limited differentiation among seasons, hosts, and counties sampled. Results also indicated the presence of common genotypes among years, suggesting that sanitation measures should be enhanced to eradicate resident P. ultimum populations. Finally, the presence of common genotypes among counties suggests that there is an exchange of infected plant material among greenhouse facilities, or that there is a common source of inoculum coming to the region. Continued monitoring of pathogen populations will enhance our understanding of population dynamics of P. ultimum in Michigan and facilitate improvement of control strategies.
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characterization of pythium species associated with greenhouse Floriculture Crops in michigan
Plant Disease, 2016Co-Authors: Johanna Del Castillo Munera, Mary K. HausbeckAbstract:Michigan ranks third in the United States for the wholesale value of Floriculture products, with an estimated value of $375.7 million. Seedling damping-off and root and crown rot are commonly caused by Pythium spp. and are important problems for greenhouse growers. Pythium spp. associated with Michigan’s Floriculture Crops were characterized as a means to improve current management strategies. During 2011 and 2012, potted poinsettias with root rot symptoms were sampled from nine greenhouses located in Kent, Kalamazoo, and Wayne counties. In 2013, from the same three counties, symptomatic geranium and snapdragon bedding plants were sampled from 12 greenhouses. Additionally, symptomatic hibiscus and lantana plants were sampled at one greenhouse facility. Isolates were confirmed to be Pythium spp. via morphology and sequencing of the ITS region. A total of 287 Pythium spp. isolates were obtained from poinsettias and 726 isolates from geranium, snapdragon, hibiscus, and lantana. Seven Pythium spp., and a grou...
H A Olson - One of the best experts on this subject based on the ideXlab platform.
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Host Specificity and Variations in Aggressiveness of North Carolina Isolates of Phytophthora cryptogea and P. drechsleri in Greenhouse Ornamental Plants.
Plant Disease, 2020Co-Authors: H A Olson, D M BensonAbstract:Abstract Three isolates of Phytophthora cryptogea and three isolates of P. drechsleri were evaluated for host specificity and variations in aggressiveness on eight Floriculture Crops commonly grown in North Carolina. Plants were monitored for the development of foliar symptoms stemming from root rot caused by Phytophthora. No isolates of P. cryptogea or P. drechsleri had the same host range, though all P. cryptogea isolates caused foliar symptoms on gerbera daisy and annual stock, and all P. drechsleri isolates incited disease on osteospermum. No African marigold plants developed foliar symptoms of Phytophthora root rot. All P. cryptogea isolates caused foliar symptoms on at least three tested plant species. Isolates of P. drechsleri varied from highly specific and only causing disease on a single host species to relatively nonspecific and causing foliar symptoms on the majority of host plants. This is the first report of host specificity of ornamental isolates of P. drechsleri, and several of the tested ...
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phylogenetic history of phytophthora cryptogea and p drechsleri isolates from Floriculture Crops in north carolina greenhouses
Phytopathology, 2011Co-Authors: H A Olson, Ignazio Carbone, D M BensonAbstract:ABSTRACT The evolutionary history of Phytophthora cryptogea and P. drechsleri isolates previously collected from Floriculture Crops in North Carolina commercial greenhouses was explored with coalescent- and parsimony-based analyses. Initially, 68 isolates representing 13 location–host groups were sequenced at multiple loci. Sequences of all isolates within a group were identical. A subset of isolates were selected, cloned to resolve heterozygous sites, and analyzed with SNAP Workbench. The internal transcribed spacer (ITS) region of the ribosomal DNA and cytochrome oxidase II gene genealogies were congruent and indicated that P. cryptogea and P. drechsleri are sister species diverged from a common ancestor with no evidence of gene flow. In contrast, genealogies inferred from β-tubulin (β-tub) and translation elongation factor 1α (EF-1α) genes were in conflict with these loci. Coalescent analysis based on a nonrecombining partition in β-tub and EF-1α showed an initial (older) split between P. cryptogea and...
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characterization of phytophthora spp on Floriculture Crops in north carolina
Plant Disease, 2011Co-Authors: H A Olson, D M BensonAbstract:Abstract Isolates of Phytophthora in Floriculture Crops were collected from North Carolina commercial greenhouse facilities in 2007 and 2008, identified, and characterized for mating type and mefenoxam sensitivity. In all, 163 isolates from 13 host species at 11 locations were identified primarily as Phytophthora nicotianae (59%), P. drechsleri (23%), P. cryptogea (9%), and P. tropicalis (4%). Multiple Phytophthora spp. were found at five locations. DNA sequencing was more reliable for differentiating P. cryptogea and P. drechsleri. Only the A1 mating type of P. drechsleri was collected; however, both mating types of P. nicotianae, P. cryptogea, and P. tropicalis were found. Overall, 66% of Phytophthora isolates were resistant or intermediate in resistance to mefenoxam at 1 μg a.i./ml. Three groups of P. drechsleri isolates had effective concentration of mefenoxam providing 50% growth inhibition (EC50) estimates over 700 μg a.i./ml. EC50 estimates for P. nicotianae ranged from 246 to 435 μg a.i./ml. Isola...
Johanna Del Castillo Munera - One of the best experts on this subject based on the ideXlab platform.
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population structure of pythium ultimum from greenhouse floral Crops in michigan
Plant Disease, 2019Co-Authors: Johanna Del Castillo Munera, L M Quesadaocampo, Alejandro Rojas, Martin I Chilvers, Mary K. HausbeckAbstract:: Pythium ultimum causes seedling damping-off and root and crown rot in greenhouse ornamental plants. To understand the population dynamics and assess population structure of P. ultimum in Michigan Floriculture Crops, simple sequence repeats (SSRs) were developed using the previously published P. ultimum predicted transcriptome. A total of 166 isolates sampled from 2011 to 2013 from five, one, and three greenhouses in Kalamazoo, Kent, and Wayne Counties, respectively, were analyzed using six polymorphic and fluorescently labeled SSR markers. The average unbiased Simpson's index (λu, 0.95), evenness (E5, 0.56), and recovery of 12 major clones out of the 65 multilocus genotypes obtained, suggests that P. ultimum is not a recent introduction into Michigan greenhouses. Analyses revealed a clonal population, with limited differentiation among seasons, hosts, and counties sampled. Results also indicated the presence of common genotypes among years, suggesting that sanitation measures should be enhanced to eradicate resident P. ultimum populations. Finally, the presence of common genotypes among counties suggests that there is an exchange of infected plant material among greenhouse facilities, or that there is a common source of inoculum coming to the region. Continued monitoring of pathogen populations will enhance our understanding of population dynamics of P. ultimum in Michigan and facilitate improvement of control strategies.
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characterization of pythium species associated with greenhouse Floriculture Crops in michigan
Plant Disease, 2016Co-Authors: Johanna Del Castillo Munera, Mary K. HausbeckAbstract:Michigan ranks third in the United States for the wholesale value of Floriculture products, with an estimated value of $375.7 million. Seedling damping-off and root and crown rot are commonly caused by Pythium spp. and are important problems for greenhouse growers. Pythium spp. associated with Michigan’s Floriculture Crops were characterized as a means to improve current management strategies. During 2011 and 2012, potted poinsettias with root rot symptoms were sampled from nine greenhouses located in Kent, Kalamazoo, and Wayne counties. In 2013, from the same three counties, symptomatic geranium and snapdragon bedding plants were sampled from 12 greenhouses. Additionally, symptomatic hibiscus and lantana plants were sampled at one greenhouse facility. Isolates were confirmed to be Pythium spp. via morphology and sequencing of the ITS region. A total of 287 Pythium spp. isolates were obtained from poinsettias and 726 isolates from geranium, snapdragon, hibiscus, and lantana. Seven Pythium spp., and a grou...
B B Shew - One of the best experts on this subject based on the ideXlab platform.
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mefenoxam sensitivity aggressiveness and identification of pythium species causing root rot on Floriculture Crops in north carolina
Plant Disease, 2015Co-Authors: E C Lookabaugh, Kelly L Ivors, B B ShewAbstract:Herbaceous ornamental plants exhibiting symptoms of Pythium root rot were collected from 26 greenhouses in 21 counties in North Carolina (NC) from 2010 to 2012. Plant symptoms ranged from mild stunting to severe wilting, root rot, and death. Roots were plated on selective media, and 356 isolates of Pythium were recovered from 34 host species. Selected isolates were identified by sequencing of the internal transcribed spacer (ITS) rDNA gene region. Seventeen Pythium species were identified, with P. aphanidermatum, P. irregulare, and P. myriotylum comprising 75% of the 320 isolates sequenced. Twelve of the 26 greenhouses had more than one species present. Mefenoxam sensitivity was tested in vitro by growing isolates in wells of microtiter plates containing clarified V8 agar amended with 100 µg a.i./ml mefenoxam. Colonization was scored after 24 to 48 h using a scale of 0 (no growth) to 5 (entire well colonized). Fifty-two percent of the isolates were resistant to mefenoxam (mean score ≥4). All 32 isolates o...