The Experts below are selected from a list of 279 Experts worldwide ranked by ideXlab platform
Lisa A. Castlebury - One of the best experts on this subject based on the ideXlab platform.
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Phomopsis stem canker a reemerging threat to sunflower helianthus annuus in the united states
Phytopathology, 2015Co-Authors: Febina M Mathew, Lisa A. Castlebury, Kholoud M Alananbeh, James G Jordahl, Scott M Meyer, T J Gulya, Samuel G MarkellAbstract:Phomopsis stem canker causes yield reductions on sunflower (Helianthus annuus L.) on several continents, including Australia, Europe, and North America. In the United States, Phomopsis stem canker incidence has increased 16-fold in the Northern Great Plains between 2001 and 2012. Although Diaporthe helianthi was assumed to be the sole causal agent in the United States, a newly described species, D. gulyae, was found to be the primary cause of Phomopsis stem canker in Australia. To determine the identity of Diaporthe spp. causing Phomopsis stem canker in the Northern Great Plains, 275 infected stems were collected between 2010 and 2012. Phylogenetic analyses of sequences of the ribosomal DNA internal transcribed spacer region, elongation factor subunit 1-α, and actin gene regions of representative isolates, in comparison with those of type specimens, confirmed two species (D. helianthi and D. gulyae) in the United States. Differences in aggressiveness between the two species were determined using the stem-...
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Characterisation of Phomopsis spp. associated with die-back of rooibos (Aspalathus linearis) in South Africa.
Studies in Mycology, 2006Co-Authors: J.c. Janse Van Rensburg, S. C. Lamprecht, Johannes Z. Groenewald, Lisa A. Castlebury, Pedro W. CrousAbstract:Die-back of rooibos (Aspalathus linearis) causes substantial losses in commercial Aspalathus plantations in South Africa. In the past, the disease has been attributed to Phomopsis phaseoli (teleomorph: Diaporthe phaseolorum). Isolates obtained from diseased plants, however, were highly variable with regard to morphology and pathogenicity. The aim of the present study was thus to identify the Phomopsis species associated with die-back of rooibos. Isolates were subjected to DNA sequence comparisons of the internal transcribed spacer region (ITS1, 5.8S, ITS2) and partial sequences of the translation elongation factor-1 alpha gene. Furthermore, isolates were also compared in glasshouse inoculation trials on 8-mo-old potted plants to evaluate their pathogenicity. Five species were identified, of which D. aspalathi (formerly identified as D. phaseolorum or D. phaseolorum var. meridionalis) proved to be the most virulent, followed by D. ambigua, Phomopsis theicola, one species of Libertella and Phomopsis, respectively, and a newly described species, P. cuppatea. A description is also provided for D. ambigua based on a newly designated epitype specimen.
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A new species of Phomopsis causing twig dieback of Vaccinium vitis-idaea (lingonberry)
Fungal Biology, 2002Co-Authors: David F. Farr, Amy Y Rossman, Lisa A. Castlebury, Melodie L. PutnamAbstract:A fungus was discovered causing a progressive twig dieback on stems of Vaccinium vitis-idaea (lingonberry) in Oregon. Both morphological and molecular data suggest that the fungus belongs in Diaporthe/Phomopsis but is distinct from P. vaccinii, cause of a dieback and fruit rot of blueberry and cranberry (Vaccinium spp.). This fungus is described and illustrated as a new species, Phomopsis columnaris. It is distinguished from other species of Phomopsis by the distinctive conidiophores that consist of vertically aligned cells lining the base and sides of the conidiomata. Another species of Phomopsis described on Vaccinium, Phomopsis myrtilli, known from V. myrtillus, is redescribed and illustrated based on authentic herbarium material.
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Morphological and molecular characterization of Phomopsis vaccinii and additional isolates of Phomopsis from blueberry and cranberry in the eastern United States.
Mycologia, 2002Co-Authors: David F. Farr, Lisa A. Castlebury, Amy Y RossmanAbstract:Forty isolates of Phomopsis were obtained from twigs and berries of highbush blueberry, Vaccinium corymbosum, and cranberry, Vaccinium macrocarpon, isolated primarily from plants grown in the eastern United States. They were characterized using conidiomatal morphology, conidial dimensions, colony appearance and growth rate, and sequences of ITS rDNA. Based on morphological and molecular similarities, most isolates grouped together with an authentic culture of Phomopsis vaccinii Shear. This taxon is described and illustrated. However, some Phomopsis isolates from Vaccinium differed in colony and conidiomatal morphology from P. vaccinii and, based on ITS sequences, were related to isolates of Phomopsis from diverse hosts. These isolates were excluded from P. vaccinii.
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Phomopsis amygdali causes peach shoot blight of cultivated peach trees in the southeastern United States
Mycologia, 1999Co-Authors: David F. Farr, Lisa A. Castlebury, Rebecca A. Pardo-schultheissAbstract:Phomopsis shoot blight of peach is an in- creasingly common fungal disease in southeastern peach growing areas of the United States. A similar disease has been reported from Europe where it oc- curs on both peach and almond. Strains of Phomopsis were obtained from peach, asian pear and plum in the United States and from almond in Spain and It- aly. Examination of the morphological, cultural and molecular characteristics of these strains showed that the Phomopsis amygdali on almond in Europe is the same as the fungus found on peach in the USA. The species of Phomopsis on plum and asian pear in the United States is different from P amygdali.
J. A. Wrather - One of the best experts on this subject based on the ideXlab platform.
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Soybean Cultivar and Foliar Fungicide Effects on Phomopsis sp. Seed Infection
Plant disease, 2004Co-Authors: J. A. Wrather, David A. Sleper, W. E. Stevens, J. G. Shannon, A. P. ArelliAbstract:Phomopsis seed decay (PSD) caused by Phomopsis spp. can be severe when soybean seed producers in the southern United States use the early soybean production system (ESPS) to avoid late-July through early-September drought damage to soybean. The usefulness of this production system would be greater if developing seed could be protected from PSD by foliar application of fungicides or by planting Phomopsis spp.-resistant soybean lines. The objective of this research was to determine the affects of the fungicides benomyl and azoxystrobin applied to soybean, at various times, on percent Phomopsis spp. infection of seed in Asgrow 3834, a PSD-susceptible cultivar, and SS93-6012, a PSD-resistant soybean line, planted in mid-April. The percent Phomopsis spp. infection of Asgrow 3834 seed averaged over years was significantly less for the benomyl (0.28 kg a.i. ha-1) applied at R3 + R5 treatment (48.6% seed infection) than the control (52.8% seed infection) and significantly greater for the azoxystrobin (0.17 kg a.i. ha-1) applied at R3 + R5 treatment (61.6% seed infection) than the control (52.8% seed infection). This method of managing PSD will not be acceptable to soybean growers. The percent of Phomopsis spp. infection of Asgrow 3834 seed averaged over years (52.8% seed infection) was significantly greater than for line SS93-6012 (2.8% seed infection). There were no differences in percent Phomopsis spp. infection of SS93-6012 seed between the control (2.8% seed infection) and benomyl treatment (4.0% seed infection). The most effective method for PSD management was to plant a resistant soybean line. Line SS93-6012 will be useful in breeding programs focused on developing high yielding PSD-resistant cultivars.
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Planting Date and Cultivar Effects on Soybean Yield, Seed Quality, and Phomopsis sp. Seed Infection.
Plant disease, 2003Co-Authors: J. A. Wrather, David A. Sleper, W. E. Stevens, J. G. Shannon, Richard F. WilsonAbstract:Incidence of Phomopsis seed decay is frequently high and quality low in seed from early-maturing maturity group III and IV soybean cultivars planted in early to mid-April in the southern United States. Cultivars resistant to this disease have not been available until the recent release of germ plasm lines SS 93-6012 and SS 93-6181. Our objective was to determine the effects of planting dates with these lines and one Phomopsis seed decay-susceptible soybean cultivar, Asgrow 3834, on seed infection by Phomopsis spp. and on yield and the correlation between percentage of Asgrow 3834 infected with Phomopsis spp. and seed quality. Generally, yields averaged over years were significantly greater for mid-April than mid-June plantings, and yields of cultivars were similar within a planting date. Soybean lines SS 93-6012 and SS 93-6181 were highly resistant to Phomopsis seed decay compared with the susceptible cultivar, Asgrow 3834. There was a significant, negative correlation between germination of seed from mid-April plantings of Asgrow 3834 and percentage of these seed infected with Phomopsis spp. Moreover, there were significant correlations between fatty acid composition of Asgrow 3834 seed and the percentage of these seed infected with Phomopsis spp. This altered composition of fatty acids may be responsible for reduced quality of oil derived from seed infected with this fungus. Phomopsis seed decay-resistant soybean lines SS 93-6012 and SS 93-6181 should be useful in breeding programs focused on developing high-yielding cultivars resistant to this disease.
Richard F. Wilson - One of the best experts on this subject based on the ideXlab platform.
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Planting Date and Cultivar Effects on Soybean Yield, Seed Quality, and Phomopsis sp. Seed Infection.
Plant disease, 2003Co-Authors: J. A. Wrather, David A. Sleper, W. E. Stevens, J. G. Shannon, Richard F. WilsonAbstract:Incidence of Phomopsis seed decay is frequently high and quality low in seed from early-maturing maturity group III and IV soybean cultivars planted in early to mid-April in the southern United States. Cultivars resistant to this disease have not been available until the recent release of germ plasm lines SS 93-6012 and SS 93-6181. Our objective was to determine the effects of planting dates with these lines and one Phomopsis seed decay-susceptible soybean cultivar, Asgrow 3834, on seed infection by Phomopsis spp. and on yield and the correlation between percentage of Asgrow 3834 infected with Phomopsis spp. and seed quality. Generally, yields averaged over years were significantly greater for mid-April than mid-June plantings, and yields of cultivars were similar within a planting date. Soybean lines SS 93-6012 and SS 93-6181 were highly resistant to Phomopsis seed decay compared with the susceptible cultivar, Asgrow 3834. There was a significant, negative correlation between germination of seed from mid-April plantings of Asgrow 3834 and percentage of these seed infected with Phomopsis spp. Moreover, there were significant correlations between fatty acid composition of Asgrow 3834 seed and the percentage of these seed infected with Phomopsis spp. This altered composition of fatty acids may be responsible for reduced quality of oil derived from seed infected with this fungus. Phomopsis seed decay-resistant soybean lines SS 93-6012 and SS 93-6181 should be useful in breeding programs focused on developing high-yielding cultivars resistant to this disease.
David F. Farr - One of the best experts on this subject based on the ideXlab platform.
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A new species of Phomopsis causing twig dieback of Vaccinium vitis-idaea (lingonberry)
Fungal Biology, 2002Co-Authors: David F. Farr, Amy Y Rossman, Lisa A. Castlebury, Melodie L. PutnamAbstract:A fungus was discovered causing a progressive twig dieback on stems of Vaccinium vitis-idaea (lingonberry) in Oregon. Both morphological and molecular data suggest that the fungus belongs in Diaporthe/Phomopsis but is distinct from P. vaccinii, cause of a dieback and fruit rot of blueberry and cranberry (Vaccinium spp.). This fungus is described and illustrated as a new species, Phomopsis columnaris. It is distinguished from other species of Phomopsis by the distinctive conidiophores that consist of vertically aligned cells lining the base and sides of the conidiomata. Another species of Phomopsis described on Vaccinium, Phomopsis myrtilli, known from V. myrtillus, is redescribed and illustrated based on authentic herbarium material.
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Morphological and molecular characterization of Phomopsis vaccinii and additional isolates of Phomopsis from blueberry and cranberry in the eastern United States.
Mycologia, 2002Co-Authors: David F. Farr, Lisa A. Castlebury, Amy Y RossmanAbstract:Forty isolates of Phomopsis were obtained from twigs and berries of highbush blueberry, Vaccinium corymbosum, and cranberry, Vaccinium macrocarpon, isolated primarily from plants grown in the eastern United States. They were characterized using conidiomatal morphology, conidial dimensions, colony appearance and growth rate, and sequences of ITS rDNA. Based on morphological and molecular similarities, most isolates grouped together with an authentic culture of Phomopsis vaccinii Shear. This taxon is described and illustrated. However, some Phomopsis isolates from Vaccinium differed in colony and conidiomatal morphology from P. vaccinii and, based on ITS sequences, were related to isolates of Phomopsis from diverse hosts. These isolates were excluded from P. vaccinii.
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Phomopsis amygdali causes peach shoot blight of cultivated peach trees in the southeastern United States
Mycologia, 1999Co-Authors: David F. Farr, Lisa A. Castlebury, Rebecca A. Pardo-schultheissAbstract:Phomopsis shoot blight of peach is an in- creasingly common fungal disease in southeastern peach growing areas of the United States. A similar disease has been reported from Europe where it oc- curs on both peach and almond. Strains of Phomopsis were obtained from peach, asian pear and plum in the United States and from almond in Spain and It- aly. Examination of the morphological, cultural and molecular characteristics of these strains showed that the Phomopsis amygdali on almond in Europe is the same as the fungus found on peach in the USA. The species of Phomopsis on plum and asian pear in the United States is different from P amygdali.
David A. Sleper - One of the best experts on this subject based on the ideXlab platform.
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Soybean Cultivar and Foliar Fungicide Effects on Phomopsis sp. Seed Infection
Plant disease, 2004Co-Authors: J. A. Wrather, David A. Sleper, W. E. Stevens, J. G. Shannon, A. P. ArelliAbstract:Phomopsis seed decay (PSD) caused by Phomopsis spp. can be severe when soybean seed producers in the southern United States use the early soybean production system (ESPS) to avoid late-July through early-September drought damage to soybean. The usefulness of this production system would be greater if developing seed could be protected from PSD by foliar application of fungicides or by planting Phomopsis spp.-resistant soybean lines. The objective of this research was to determine the affects of the fungicides benomyl and azoxystrobin applied to soybean, at various times, on percent Phomopsis spp. infection of seed in Asgrow 3834, a PSD-susceptible cultivar, and SS93-6012, a PSD-resistant soybean line, planted in mid-April. The percent Phomopsis spp. infection of Asgrow 3834 seed averaged over years was significantly less for the benomyl (0.28 kg a.i. ha-1) applied at R3 + R5 treatment (48.6% seed infection) than the control (52.8% seed infection) and significantly greater for the azoxystrobin (0.17 kg a.i. ha-1) applied at R3 + R5 treatment (61.6% seed infection) than the control (52.8% seed infection). This method of managing PSD will not be acceptable to soybean growers. The percent of Phomopsis spp. infection of Asgrow 3834 seed averaged over years (52.8% seed infection) was significantly greater than for line SS93-6012 (2.8% seed infection). There were no differences in percent Phomopsis spp. infection of SS93-6012 seed between the control (2.8% seed infection) and benomyl treatment (4.0% seed infection). The most effective method for PSD management was to plant a resistant soybean line. Line SS93-6012 will be useful in breeding programs focused on developing high yielding PSD-resistant cultivars.
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Planting Date and Cultivar Effects on Soybean Yield, Seed Quality, and Phomopsis sp. Seed Infection.
Plant disease, 2003Co-Authors: J. A. Wrather, David A. Sleper, W. E. Stevens, J. G. Shannon, Richard F. WilsonAbstract:Incidence of Phomopsis seed decay is frequently high and quality low in seed from early-maturing maturity group III and IV soybean cultivars planted in early to mid-April in the southern United States. Cultivars resistant to this disease have not been available until the recent release of germ plasm lines SS 93-6012 and SS 93-6181. Our objective was to determine the effects of planting dates with these lines and one Phomopsis seed decay-susceptible soybean cultivar, Asgrow 3834, on seed infection by Phomopsis spp. and on yield and the correlation between percentage of Asgrow 3834 infected with Phomopsis spp. and seed quality. Generally, yields averaged over years were significantly greater for mid-April than mid-June plantings, and yields of cultivars were similar within a planting date. Soybean lines SS 93-6012 and SS 93-6181 were highly resistant to Phomopsis seed decay compared with the susceptible cultivar, Asgrow 3834. There was a significant, negative correlation between germination of seed from mid-April plantings of Asgrow 3834 and percentage of these seed infected with Phomopsis spp. Moreover, there were significant correlations between fatty acid composition of Asgrow 3834 seed and the percentage of these seed infected with Phomopsis spp. This altered composition of fatty acids may be responsible for reduced quality of oil derived from seed infected with this fungus. Phomopsis seed decay-resistant soybean lines SS 93-6012 and SS 93-6181 should be useful in breeding programs focused on developing high-yielding cultivars resistant to this disease.
