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Elizabeth A. Baldwin - One of the best experts on this subject based on the ideXlab platform.
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Huanglongbing increases Diplodia stem end rot in Citrus sinensis
2018Co-Authors: Wei Zhao, Jinhe Bai, Greg Mccollum, Elizabeth A. BaldwinAbstract:Huanglongbing (HLB), one of the most devastating diseases of citrus is caused by the α-Proteobacteria Candidatus Liberibacter. Diplodia natalensis Pole-Evans is a fungal pathogen which has been known to cause a postharvest stem-end rot of citrus, the pathogen infects citrus fruit under the calyx, and the fruit decay typically occurs following harvest and is exacerbated by exposure to ethylene. In this study, we report that high incidence of Diplodia infection in HLB symptomatic fruit. The incidence of SER in 300 ʻHamlinʼ and 300 ʻValenciaʼ orange fruit, with or without ethylene treatment was determined. Two weeks following exposure to ethylene (10 ppm, four days), the incidence of SER in HLB-symptomatic fruit was as high as 66.7% (ʻHamlinʼ) and 58.7% (ʻValenciaʼ); whereas for asymptomatic fruit, less than 10% of the fruit were affected by SER. Confirmation of Diplodia in calyx abscission zone was by qPCR validation of the isolates and morphology of conidia.
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Correlation of Diplodia (LasioDiplodia theobromae) infection, huanglongbing, ethylene production, fruit removal force and pre-harvest fruit drop
Scientia Horticulturae, 2016Co-Authors: Wei Zhao, Tim R. Gottwald, Jinhe Bai, Greg Mccollum, Mike Irey, Anne Plotto, Elizabeth A. BaldwinAbstract:Abstract Citrus greening or huanglonbing (HLB) is thought to be caused by Candidatus Liberibacter asiaticus (CLas) and is devastating the citrus industry worldwide. One symptom of HLB disease is excessive pre-harvest fruit drop. Recently, higher incidence of LasioDiplodia theobromae (Diplodia) was found in HLB-symptomatic orange calyx abscission zones (AZ-C) than in non-symptomatic fruit, and the infection was positively correlated with the reduction in fruit detachment force (FDF), suggesting that Diplodia infection may be involved in the HLB-related pre-harvest fruit drop. To verify the hypothesis, we conducted two experiments. Experiment 1 was conducted by shaking HLB-affected ‘Hamlin’ and ‘Valencia’ orange trees during the harvest season (twice for ‘Hamlin’ and once for ‘Valencia’). The fruit that dropped from trees upon shaking were collected (D), and the fruit retained on trees after shaking were harvested (R). Fruit ethylene production was measured, and the levels of Diplodia and CLas in AZ-C of D and R fruit were analyzed. The results revealed significantly higher levels of Diplodia in D compared with R fruit; and ethylene was produced from more than half of the D fruit but none of the R fruit. Ethylene production was positively correlated with Diplodia level in D fruit. In experiment 2, a preliminary trial on the effect of fungicide (Quadris Top) application on incidence of Diplodia infection and fruit drop was investigated. The experiment was conducted in a commercial grove with essentially 100% of the trees being HLB-symptomatic, and included five citrus cultivars (‘Early Gold’ orange, ‘Midsweet’ orange, ‘Murcott’ tangor, ‘Navel’ orange and ‘Ray Ruby’ grapefruit). Diplodia levels were lower and FDF significantly higher in fungicide-treated compared to non-treated ‘Early Gold’, ‘Midsweet’ and ‘Murcott’ fruit, and consequently, the fruit drop was reduced by 45%, 30% and 46% that of non-sprayed controls, respectively. For ‘Navel’ or ‘Ray Ruby’ fruit, there was no significant change between sprayed and non-sprayed controls in the level of Diplodia, FDF or fruit-drop. The results consistently showed a positive correlation between Diplodia infection and fruit drop in HLB-affected fruit, indicating the possible involvement of the fungus in HLB-related excessive fruit drop. This suggests that control of Diplodia fungal infection in the field may reduce HLB-associated pre-harvest fruit drop.
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high incidence of preharvest colonization of huanglongbing symptomatic citrus sinensis fruit by lasioDiplodia theobromae Diplodia natalensis and exacerbation of postharvest fruit decay by that fungus
Applied and Environmental Microbiology, 2015Co-Authors: Wei Zhao, Jinhe Bai, Greg Mccollum, Elizabeth A. BaldwinAbstract:Huanglongbing (HLB), presumably caused by the bacterium “Candidatus Liberibacter asiaticus,” is a devastating citrus disease associated with excessive preharvest fruit drop. LasioDiplodia theobromae (Diplodia) is the causal organism of citrus stem end rot (SER). The pathogen infects citrus fruit under the calyx abscission zone (AZ-C) and is associated with cell wall hydrolytic enzymes similar to plant enzymes involved in abscission. By means of DNA sequencing, Diplodia was found in “Ca. Liberibacter asiaticus”-positive juice from HLB-symptomatic fruit (S) but not in “Ca. Liberibacter asiaticus”-negative juice. Therefore, the incidence of Diplodia in fruit tissues, the impact on HLB-related postharvest decay, and the implications for HLB-related preharvest fruit drop were investigated in Hamlin and Valencia oranges. Quantitative PCR results (qPCR) revealed a significantly (P < 0.001) greater incidence of Diplodia in the AZ-C of HLB-symptomatic (S; “Ca. Liberibacter asiaticus” threshold cycle [CT] of <30) than in the AZ-C of in asymptomatic (AS; “Ca. Liberibacter asiaticus” CT of ≥30) fruit. In agreement with the qPCR results, 2 weeks after exposure to ethylene, the incidences of SER in S fruit were 66.7% (Hamlin) and 58.7% (Valencia), whereas for AS fruit the decay rates were 6.7% (Hamlin) and 5.3% (Valencia). Diplodia colonization of S fruit AZ-C was observed by scanning electron microscopy and confirmed by PCR test and morphology of conidia in isolates from the AZ-C after surface sterilization. Diplodia CT values were negatively correlated with ethylene production (R = −0.838 for Hamlin; R = −0.858 for Valencia) in S fruit, and positively correlated with fruit detachment force (R = 0.855 for Hamlin; R = 0.850 for Valencia), suggesting that Diplodia colonization in AZ-C may exacerbate HLB-associated preharvest fruit drop.
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High incidence of preharvest colonization of huanglongbing-symptomatic citrus sinensis fruit by LasioDiplodia theobromae (Diplodia natalensis) and exacerbation of postharvest fruit decay by that fungus.
Applied and environmental microbiology, 2014Co-Authors: Wei Zhao, Jinhe Bai, Greg Mccollum, Elizabeth A. BaldwinAbstract:Huanglongbing (HLB), presumably caused by the bacterium “Candidatus Liberibacter asiaticus,” is a devastating citrus disease associated with excessive preharvest fruit drop. LasioDiplodia theobromae (Diplodia) is the causal organism of citrus stem end rot (SER). The pathogen infects citrus fruit under the calyx abscission zone (AZ-C) and is associated with cell wall hydrolytic enzymes similar to plant enzymes involved in abscission. By means of DNA sequencing, Diplodia was found in “Ca. Liberibacter asiaticus”-positive juice from HLB-symptomatic fruit (S) but not in “Ca. Liberibacter asiaticus”-negative juice. Therefore, the incidence of Diplodia in fruit tissues, the impact on HLB-related postharvest decay, and the implications for HLB-related preharvest fruit drop were investigated in Hamlin and Valencia oranges. Quantitative PCR results (qPCR) revealed a significantly (P < 0.001) greater incidence of Diplodia in the AZ-C of HLB-symptomatic (S; “Ca. Liberibacter asiaticus” threshold cycle [CT] of
Glen R. Stanosz - One of the best experts on this subject based on the ideXlab platform.
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Detection of the Diplodia shoot blight and canker pathogens from red and jack pine seeds using cultural methods
Canadian Journal of Plant Pathology, 2014Co-Authors: Denise R. Smith, Glen R. Stanosz, Jana AlbersAbstract:AbstractThe shoot blight and canker pathogens Diplodia pinea and D. scrobiculata commonly and abundantly sporulate on seed cones of red pine (Pinus resinosa) and jack pine (P. banksiana) collected from Wisconsin and Minnesota forests. Cultural methods were used to investigate the incidence of these fungi in seed lots obtained from government nurseries in these states. In each of three replicate trials, seeds of each lot were assigned to four treatments before incubation on semi-selective medium: (1) not surface-disinfested; (2) surface-disinfested; (3) surface-disinfested, then inoculated with D. pinea conidia; or (4) not surface-disinfested, then inoculated with D. pinea conidia. For red pine seeds, the mean percentage positive was 2.7% for treatment 1 and 1.3% for treatment 2. Jack pine seeds were less frequently positive than red pine seeds for both treatments 1 and 2. The Diplodia species cultured was identified as D. pinea in almost every case. Diplodia pinea was much less frequently recovered from s...
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Diplodia Shoot Blight Damage to Understory Red Pine Seedlings
Northern Journal of Applied Forestry, 2013Co-Authors: Brent W. Oblinger, Denise R. Smith, Glen R. StanoszAbstract:The fungal pathogen Diplodia pinea has caused substantial damage to red pine (Pinus resinosa Ait.) seedlings in nurseries, but the impact of Diplodia shoot blight on naturally occurring seedlings has not been thoroughly investigated. In 2008, incidence and severity of Diplodia shoot blight symptoms on living red pine seedlings and shoot blight-associated mortality of seedlings were quantified in understories of mature plantations at four sites in Wisconsin. Blighted shoots were examined for characteristic fruiting structures of the pathogen and a species-specific polymerase chain reaction (PCR) assay confirmed D. pinea as present on these shoots. Mean seedling mortality ranged from 13 to 31% and shoot blight incidence on living seedlings was ≥ 94% at each site. Mean damage severity ratings on a scale from 0 to 3 ranged from 2.16 to 2.98, with evidence of previous blighting of leaders on ≥ 54% of seedlings. These results document Diplodia shoot blight damage to naturally occurring understory trees and the potential for this disease to impede efforts to naturally regenerate red pine stands.
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Red pine harvest debris as a potential source of inoculum of Diplodia shoot blight pathogens
Forest Ecology and Management, 2011Co-Authors: Brent W. Oblinger, Denise R. Smith, Glen R. StanoszAbstract:Abstract A high incidence of Diplodia shoot blight (site means ranging 85–100%) was observed on recently planted red pine (Pinus resinosa) seedlings where mature red pine stands previously had been clearcut. An investigation of the potential of harvest debris as a source of inoculum of Diplodia pathogens then was conducted. Cones, bark, needles, stems from shoots bearing needles, and stems from shoots not bearing needles (both suspended above the soil and in soil contact) were collected from harvest debris left at sites where clearcutting occurred. Conidia were quantified, and their germination rate was assessed, and Diplodia species were identified using PCR. Conidia of Diplodia species were found at all study sites and conidia counts increased from samples collected from 6 to 18 months after harvest. Germinable conidia were obtained from debris collected 6 months to 5 years after harvest. Fewer conidia were obtained from debris collected at intervals of up to 4–5 years after harvest and the percentage of germinable conidia was lower after longer intervals following harvest. More conidia were obtained and a greater percentage germinated from debris collected above the soil than from debris in soil contact. The host substrate also influenced the number of conidia and the percentage that germinated. Planting red pine seedlings next to debris infested with Diplodia pathogens could provide a persistent source of inoculum. Results should prompt further consideration by land managers and researchers of the potential forest health risks, in addition to benefits, that may be associated with harvest debris.
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Diplodia pinea, the Cause of Diplodia Blight of Pines, Confirmed in Alabama, Louisiana, and Mississippi
Plant disease, 2009Co-Authors: Glen R. Stanosz, Denise R. Smith, Stephen W. Fraedrich, Richard E. Baird, A. ManginiAbstract:Loblolly pine (Pinus taeda) is the major commercial pine species cultivated in the Gulf Coast Region of the southern United States. Symptoms of Diplodia shoot blight (including yellow and brown needles and resin-soaked, dead, small twigs), pycnidia with conidia typical of Diplodia pinea on blighted shoots, and damaged, immature seed cones were observed during the summer of 2007 in loblolly pine seed orchards near Ward, AL, Winn Parish, LA, and Moselle, MS. Similar conidia also were obtained from pycnidia on opened seed cones of longleaf pine (P. palustris) collected on the campus of Mississipi State University, Starkville. Pure cultures obtained from specimens collected at each location were confirmed as D. pinea using species-specific PCR primers (3) that allow differentiation of D. pinea from the similar pine shoot blight pathogen D. scrobiculata. Isolates from loblolly pines in Alabama (07-58), Louisiana (07-38), and Mississippi (06-45) were used individually to inoculate potted 6- to 7-month-old loblolly pine seedlings grown from seed in a greenhouse in each of two independent trials. Elongating terminal shoots of seedlings to be inoculated were wounded by removing a needle fascicle ∼2 cm below the shoot apex. A 4-mm-diameter plug cut from an actively growing colony on water agar (WA) was placed on the wound, mycelium side toward the stem. Noncolonized WA plugs were placed in the same manner on similarly wounded control seedlings and nonwounded control seedlings also were used. Parafilm was wrapped around the shoots to hold the agar plugs in place and was removed after 1 week. Each of the five isolate-treatment combinations was applied to seven (trial 1) or eight (trial 2) seedlings (35 and 40 seedlings per trial, respectively). One week after inoculation, small, brown lesions were visible at the point of inoculation on stems of most of the inoculated seedlings. At 25 days after inoculation, all inoculated seedlings exhibited needle browning and stem cankers ranging from 0.6 cm to 9.0 cm long (mean 2.5 cm) that girdled and killed distal portions of the shoots of ∼25% of the inoculated seedlings in each trial. Wounded control and nonwounded control seedlings did not develop symptoms. Stem segments including the point of inoculation (or comparable segments of wounded and nonwounded control seedlings) were excised, surface disinfested, and incubated on tannic acid agar with sterile red pine needles. D. pinea was cultured from all inoculated seedlings and also from one wounded control seedling. Although occurrence of D. pinea on Cedrus spp. is included in an index (1), to our knowledge this is the first confirmed report of D. pinea on pines in Alabama, Louisiana, and Mississippi. The degree of risk presented by D. pinea to loblolly pine, longleaf pine, and other pine species native to the southern United States when grown in their native ranges is unknown. Reports of Diplodia shoot blight of southern U.S. pines when grown as exotics in the southern hemisphere (4) and the potential for epidemics to develop suddenly under severe weather conditions (2,4) justify additional studies to evaluate the potential for damage to these hosts in their native ranges. References: (1) Anonymous. Page 333 in: Index of Plant Diseases in the United States. Agric. Handb. 165, U.S. Dep. Agric. Washington, DC, 1960. (2) T. H. Nicholls and M. E. Ostry. Plant Dis. 74:54, 1990. (3) D. R. Smith and G. R. Stanosz. Plant Dis. 90:307, 2006. (4) W. J. Swart and M. J. Wingfield. Plant Dis. 75:761, 1991.
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Site-related influences on cone-borne inoculum and asymptomatic persistence of Diplodia shoot blight fungi on or in mature red pines
Forest Ecology and Management, 2009Co-Authors: Isabel A. Munck, Denise R. Smith, Theodore A. Sickley, Glen R. StanoszAbstract:The shoot blight and canker pathogens Diplodia pinea and D. scrobiculata sporulate abundantly on cones of many pine hosts. Variation in incidence and abundance of potential inoculum from cones and frequency of asymptomatic persistence on or in shoots was examined for mature red pines in sites differing in dominant presettlement vegetation and soil type in Bayfield and Douglas counties in northern Wisconsin. Collections were made in each county from 6 plantations, 3 each in areas historically vegetated with jack pine and soils mapped as sands and three in areas historically vegetated with red pine with soils mapped as loamy sands. At each site, 5 cones were collected from each of 5 red pines and 10 shoots were collected from up to 5 red pines. Conidia from cones were quantified with a water wash and filtration technique. Diplodia species were cultured from surface-disinfested asymptomatic shoots. A species-specific PCR assay was used to identify the Diplodia species from cones and shoots. Although cones and asymptomatic shoots from each county yielded D. pinea and D. scrobiculata, D. pinea was detected more frequently. More conidia were obtained from cones from Douglas Co., where there is a history of severe shoot blight damage, than cones from Bayfield Co. In Douglas Co., more conidia were obtained from cones from plantations in areas of more sandy soil and presettlement jack pine dominance than cones from plantations in areas of less sandy soil and presettlement red pine dominance. The numbers of conidia and frequencies of cultural detection of Diplodia species from asymptomatic shoots at a site were positively correlated. These results provide evidence for site-related influences on abundance of pathogen inoculum and asymptomatic persistence on or in red pine crowns that may contribute to differences in frequency and severity of damage from Diplodia shoot blight.
Wei Zhao - One of the best experts on this subject based on the ideXlab platform.
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Huanglongbing increases Diplodia stem end rot in Citrus sinensis
2018Co-Authors: Wei Zhao, Jinhe Bai, Greg Mccollum, Elizabeth A. BaldwinAbstract:Huanglongbing (HLB), one of the most devastating diseases of citrus is caused by the α-Proteobacteria Candidatus Liberibacter. Diplodia natalensis Pole-Evans is a fungal pathogen which has been known to cause a postharvest stem-end rot of citrus, the pathogen infects citrus fruit under the calyx, and the fruit decay typically occurs following harvest and is exacerbated by exposure to ethylene. In this study, we report that high incidence of Diplodia infection in HLB symptomatic fruit. The incidence of SER in 300 ʻHamlinʼ and 300 ʻValenciaʼ orange fruit, with or without ethylene treatment was determined. Two weeks following exposure to ethylene (10 ppm, four days), the incidence of SER in HLB-symptomatic fruit was as high as 66.7% (ʻHamlinʼ) and 58.7% (ʻValenciaʼ); whereas for asymptomatic fruit, less than 10% of the fruit were affected by SER. Confirmation of Diplodia in calyx abscission zone was by qPCR validation of the isolates and morphology of conidia.
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Correlation of Diplodia (LasioDiplodia theobromae) infection, huanglongbing, ethylene production, fruit removal force and pre-harvest fruit drop
Scientia Horticulturae, 2016Co-Authors: Wei Zhao, Tim R. Gottwald, Jinhe Bai, Greg Mccollum, Mike Irey, Anne Plotto, Elizabeth A. BaldwinAbstract:Abstract Citrus greening or huanglonbing (HLB) is thought to be caused by Candidatus Liberibacter asiaticus (CLas) and is devastating the citrus industry worldwide. One symptom of HLB disease is excessive pre-harvest fruit drop. Recently, higher incidence of LasioDiplodia theobromae (Diplodia) was found in HLB-symptomatic orange calyx abscission zones (AZ-C) than in non-symptomatic fruit, and the infection was positively correlated with the reduction in fruit detachment force (FDF), suggesting that Diplodia infection may be involved in the HLB-related pre-harvest fruit drop. To verify the hypothesis, we conducted two experiments. Experiment 1 was conducted by shaking HLB-affected ‘Hamlin’ and ‘Valencia’ orange trees during the harvest season (twice for ‘Hamlin’ and once for ‘Valencia’). The fruit that dropped from trees upon shaking were collected (D), and the fruit retained on trees after shaking were harvested (R). Fruit ethylene production was measured, and the levels of Diplodia and CLas in AZ-C of D and R fruit were analyzed. The results revealed significantly higher levels of Diplodia in D compared with R fruit; and ethylene was produced from more than half of the D fruit but none of the R fruit. Ethylene production was positively correlated with Diplodia level in D fruit. In experiment 2, a preliminary trial on the effect of fungicide (Quadris Top) application on incidence of Diplodia infection and fruit drop was investigated. The experiment was conducted in a commercial grove with essentially 100% of the trees being HLB-symptomatic, and included five citrus cultivars (‘Early Gold’ orange, ‘Midsweet’ orange, ‘Murcott’ tangor, ‘Navel’ orange and ‘Ray Ruby’ grapefruit). Diplodia levels were lower and FDF significantly higher in fungicide-treated compared to non-treated ‘Early Gold’, ‘Midsweet’ and ‘Murcott’ fruit, and consequently, the fruit drop was reduced by 45%, 30% and 46% that of non-sprayed controls, respectively. For ‘Navel’ or ‘Ray Ruby’ fruit, there was no significant change between sprayed and non-sprayed controls in the level of Diplodia, FDF or fruit-drop. The results consistently showed a positive correlation between Diplodia infection and fruit drop in HLB-affected fruit, indicating the possible involvement of the fungus in HLB-related excessive fruit drop. This suggests that control of Diplodia fungal infection in the field may reduce HLB-associated pre-harvest fruit drop.
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high incidence of preharvest colonization of huanglongbing symptomatic citrus sinensis fruit by lasioDiplodia theobromae Diplodia natalensis and exacerbation of postharvest fruit decay by that fungus
Applied and Environmental Microbiology, 2015Co-Authors: Wei Zhao, Jinhe Bai, Greg Mccollum, Elizabeth A. BaldwinAbstract:Huanglongbing (HLB), presumably caused by the bacterium “Candidatus Liberibacter asiaticus,” is a devastating citrus disease associated with excessive preharvest fruit drop. LasioDiplodia theobromae (Diplodia) is the causal organism of citrus stem end rot (SER). The pathogen infects citrus fruit under the calyx abscission zone (AZ-C) and is associated with cell wall hydrolytic enzymes similar to plant enzymes involved in abscission. By means of DNA sequencing, Diplodia was found in “Ca. Liberibacter asiaticus”-positive juice from HLB-symptomatic fruit (S) but not in “Ca. Liberibacter asiaticus”-negative juice. Therefore, the incidence of Diplodia in fruit tissues, the impact on HLB-related postharvest decay, and the implications for HLB-related preharvest fruit drop were investigated in Hamlin and Valencia oranges. Quantitative PCR results (qPCR) revealed a significantly (P < 0.001) greater incidence of Diplodia in the AZ-C of HLB-symptomatic (S; “Ca. Liberibacter asiaticus” threshold cycle [CT] of <30) than in the AZ-C of in asymptomatic (AS; “Ca. Liberibacter asiaticus” CT of ≥30) fruit. In agreement with the qPCR results, 2 weeks after exposure to ethylene, the incidences of SER in S fruit were 66.7% (Hamlin) and 58.7% (Valencia), whereas for AS fruit the decay rates were 6.7% (Hamlin) and 5.3% (Valencia). Diplodia colonization of S fruit AZ-C was observed by scanning electron microscopy and confirmed by PCR test and morphology of conidia in isolates from the AZ-C after surface sterilization. Diplodia CT values were negatively correlated with ethylene production (R = −0.838 for Hamlin; R = −0.858 for Valencia) in S fruit, and positively correlated with fruit detachment force (R = 0.855 for Hamlin; R = 0.850 for Valencia), suggesting that Diplodia colonization in AZ-C may exacerbate HLB-associated preharvest fruit drop.
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High incidence of preharvest colonization of huanglongbing-symptomatic citrus sinensis fruit by LasioDiplodia theobromae (Diplodia natalensis) and exacerbation of postharvest fruit decay by that fungus.
Applied and environmental microbiology, 2014Co-Authors: Wei Zhao, Jinhe Bai, Greg Mccollum, Elizabeth A. BaldwinAbstract:Huanglongbing (HLB), presumably caused by the bacterium “Candidatus Liberibacter asiaticus,” is a devastating citrus disease associated with excessive preharvest fruit drop. LasioDiplodia theobromae (Diplodia) is the causal organism of citrus stem end rot (SER). The pathogen infects citrus fruit under the calyx abscission zone (AZ-C) and is associated with cell wall hydrolytic enzymes similar to plant enzymes involved in abscission. By means of DNA sequencing, Diplodia was found in “Ca. Liberibacter asiaticus”-positive juice from HLB-symptomatic fruit (S) but not in “Ca. Liberibacter asiaticus”-negative juice. Therefore, the incidence of Diplodia in fruit tissues, the impact on HLB-related postharvest decay, and the implications for HLB-related preharvest fruit drop were investigated in Hamlin and Valencia oranges. Quantitative PCR results (qPCR) revealed a significantly (P < 0.001) greater incidence of Diplodia in the AZ-C of HLB-symptomatic (S; “Ca. Liberibacter asiaticus” threshold cycle [CT] of
Alan J. L. Phillips - One of the best experts on this subject based on the ideXlab platform.
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Diplodia quercivora sp. nov.: a new species of Diplodia found on declining Quercus canariensis trees in Tunisia
Mycologia, 2013Co-Authors: Benedetto Teodoro Linaldeddu, Artur Alves, Antonio Franceschini, Alan J. L. PhillipsAbstract:During a study of the species of Botryosphaeriaceae associated with oak decline in Tunisia, a large collection of Diplodia strains were isolated from Quercus afares, Q. canariensis and Q. suber tre...
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Resolving the Diplodia complex on apple and other Rosaceae hosts
Persoonia, 2012Co-Authors: Alan J. L. Phillips, J. Lopes, Jafar Abdollahzadeh, S. G. Bobev, Artur AlvesAbstract:Diplodia species are known as pathogens on many woody hosts, including fruit trees, worldwide. In this study a collection of Diplodia isolates obtained mostly from apple and other Rosaceae hosts were identified based on morphological characters and DNA sequence data from ITS and EF1-α loci. The results show that the diversity of species associated with twig and branch cankers and fruit rot of apples is larger than previously recognised. Four species were identified, namely D. seriata and D. malorum (which is here reinstated for isolates with D. mutila-like conidia). Diplodia intermedia sp. nov. is closely related to D. seriata, and D. bulgarica sp. nov. is morphologically and phylogenetically distinct from all Diplodia species reported from apples.
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Diplodia seriata, the anamorph of "Botryosphaeria" obtusa
Fungal Diversity, 2007Co-Authors: Alan J. L. Phillips, Pedro W. Crous, Artur AlvesAbstract:The correct name to use for the anamorph of Botryosphaeria obtusa has been uncertain for many years. Since the genus name Botryophaeria is no longer available for this fungus the question of the correct Diplodia anamorph name must be resolved. Therefore, the aims of this work were to determine the correct name to apply to the anamorph of "B." obtusa through a study of relevant type specimens. The phylogenetic relationship of the species to its nearest relatives, and phylogenetic variation within the species were determined through a study of ITS sequence data. The species was shown to be relatively homogenous, cosmopolitan and plurivorous. The name Diplodia seriata was shown to be the oldest suitable name available. An epitype specimen is designated.
Artur Alves - One of the best experts on this subject based on the ideXlab platform.
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STUDIES IN MYCOLOGY 55: 235–253. 2006. Phylogenetic lineages in the Botryosphaeriaceae
2013Co-Authors: Pedro W. Crous, Artur Alves, Michael J. Wingfield, John Rheeder, Walter F. O. Marasas, Alan J. L, Treena Burgess, Paul Barber, Johannes Z GroenewaldAbstract:Abstract: Botryosphaeria is a species-rich genus with a cosmopolitan distribution, commonly associated with dieback and cankers of woody plants. As many as 18 anamorph genera have been associated with Botryosphaeria, most of which have been reduced to synonymy under Diplodia (conidia mostly ovoid, pigmented, thick-walled), or Fusicoccum (conidia mostly fusoid, hyaline, thin-walled). However, there are numerous conidial anamorphs having morphological characteristics intermediate between Diplodia and Fusicoccum, and there are several records of species outside the Botryosphaeriaceae that have anamorphs apparently typical of Botryosphaeria s.str. Recent studies have also linked Botryosphaeria to species with pigmented, septate ascospores, and Dothiorella anamorphs, or Fusicoccum anamorphs with Dichomera synanamorphs. The aim of this study was to employ DNA sequence data of the 28S rDNA to resolve apparent lineages within the Botryosphaeriaceae. From these data, 12 clades are recognised. Two of these lineages clustered outside the Botryosphaeriaceae, namely Diplodia-like anamorphs occurring on maize, which are best accommodated in Stenocarpella (Diaporthales), as well as an unresolved clade including species of Camarosporium/MicroDiplodia. We recognise 10 lineages within the Botryosphaeriaceae, including an unresolved clade (Diplodia/LasioDiplodia/Tiarosporella), Botryosphaeri
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Diplodia quercivora sp. nov.: a new species of Diplodia found on declining Quercus canariensis trees in Tunisia
Mycologia, 2013Co-Authors: Benedetto Teodoro Linaldeddu, Artur Alves, Antonio Franceschini, Alan J. L. PhillipsAbstract:During a study of the species of Botryosphaeriaceae associated with oak decline in Tunisia, a large collection of Diplodia strains were isolated from Quercus afares, Q. canariensis and Q. suber tre...
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Resolving the Diplodia complex on apple and other Rosaceae hosts
Persoonia, 2012Co-Authors: Alan J. L. Phillips, J. Lopes, Jafar Abdollahzadeh, S. G. Bobev, Artur AlvesAbstract:Diplodia species are known as pathogens on many woody hosts, including fruit trees, worldwide. In this study a collection of Diplodia isolates obtained mostly from apple and other Rosaceae hosts were identified based on morphological characters and DNA sequence data from ITS and EF1-α loci. The results show that the diversity of species associated with twig and branch cankers and fruit rot of apples is larger than previously recognised. Four species were identified, namely D. seriata and D. malorum (which is here reinstated for isolates with D. mutila-like conidia). Diplodia intermedia sp. nov. is closely related to D. seriata, and D. bulgarica sp. nov. is morphologically and phylogenetically distinct from all Diplodia species reported from apples.
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Diplodia seriata, the anamorph of "Botryosphaeria" obtusa
Fungal Diversity, 2007Co-Authors: Alan J. L. Phillips, Pedro W. Crous, Artur AlvesAbstract:The correct name to use for the anamorph of Botryosphaeria obtusa has been uncertain for many years. Since the genus name Botryophaeria is no longer available for this fungus the question of the correct Diplodia anamorph name must be resolved. Therefore, the aims of this work were to determine the correct name to apply to the anamorph of "B." obtusa through a study of relevant type specimens. The phylogenetic relationship of the species to its nearest relatives, and phylogenetic variation within the species were determined through a study of ITS sequence data. The species was shown to be relatively homogenous, cosmopolitan and plurivorous. The name Diplodia seriata was shown to be the oldest suitable name available. An epitype specimen is designated.
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Phylogenetic lineages in the Botryosphaeriaceae
Studies in mycology, 2006Co-Authors: Pedro W. Crous, Artur Alves, Paul R. Barber, Bernard Slippers, Michael J. Wingfield, John Rheeder, Walter F. O. Marasas, Treena I. Burgess, Alan J.l. Philips, Johannes Z GroenewaldAbstract:Botryosphaeria is a species-rich genus with a cosmopolitan distribution, commonly associated with dieback and cankers of woody plants. As many as 18 anamorph genera have been associated with Botryosphaeria, most of which have been reduced to synonymy under Diplodia (conidia mostly ovoid, pigmented, thick-walled), or Fusicoccum (conidia mostly fusoid, hyaline, thin-walled). However, there are numerous conidial anamorphs having morphological characteristics intermediate between Diplodia and Fusicoccum, and there are several records of species outside the Botryosphaeriaceae that have anamorphs apparently typical of Botryosphaeria s.str. Recent studies have also linked Botryosphaeria to species with pigmented, septate ascospores, and Dothiorella anamorphs, or Fusicoccum anamorphs with Dichomera synanamorphs. The aim of this study was to employ DNA sequence data of the 28S rDNA to resolve apparent lineages within the Botryosphaeriaceae. From these data, 12 clades are recognised. Two of these lineages clustered outside the Botryosphaeriaceae, namely Diplodia-like anamorphs occurring on maize, which are best accommodated in Stenocarpella (Diaporthales), as well as an unresolved clade including species of Camarosporium/MicroDiplodia. We recognise 10 lineages within the Botryosphaeriaceae, including an unresolved clade (Diplodia/LasioDiplodia/Tiarosporella), Botryosphaeria s.str. (Fusicoccum anamorphs), Macrophomina, Neoscytalidium gen. nov., Dothidotthia (Dothiorella anamorphs), Neofusicoccum gen. nov. (Botryosphaeria-like teleomorphs, Dichomera-like synanamorphs), Pseudofusicoccum gen. nov., Saccharata (Fusicoccum- and Diplodia-like synanamorphs), "Botryosphaeria" quercuum (Diplodia-like anamorph), and Guignardia (Phyllosticta anamorphs). Separate teleomorph and anamorph names are not provided for newly introduced genera, even where both morphs are known. The taxonomy of some clades and isolates (e.g. B. mamane) remains unresolved due to the absence of ex-type cultures. Taxonomic novelties: Neofusicoccum Crous, Slippers & A.J.L. Phillips gen. nov., Neofusicoccum andinum (Mohali, Slippers & M.J. Wingf.) Mohali, Slippers & M.J. Wingf. comb. nov., Neofusicoccum arbuti (D.F. Farr & M. Elliott) Crous, Slippers & A.J.L. Phillips comb. nov., Neofusicoccum australe (Slippers, Crous & M.J. Wingf.) Crous, Slippers & A.J.L. Phillips comb. nov., Neofusicoccum eucalypticola (Slippers Crous & M.J. Wingf.) Crous, Slippers & A.J.L. Phillips comb. nov., Neofusicoccum eucalyptorum (Crous, H. Smith & M.J. Wingf.) Crous, Slippers & A.J.L. Phillips comb. nov., Neofusicoccum luteum (Pennycook & Samuels) Crous, Slippers & A.J.L. Phillips comb. nov., Neofusicoccum macroclavatum (Burgess, Barber & Hardy) Burgess, Barber & Hardy comb. nov., Neofusicoccum mangiferae (Syd. & P. Syd.) Crous, Slippers & A.J.L. Phillips comb. nov., Neofusicoccum parvum (Pennycook & Samuels) Crous, Slippers & A.J.L. Phillips comb. nov., Neofusicoccum protearum (Denman & Crous) Crous, Slippers & A.J.L. Phillips comb. nov., Neofusicoccum ribis (Slippers, Crous & M.J. Wingf.) Crous, Slippers & A.J.L. Phillips comb. nov., Neofusicoccum viticlavatum (Niekerk & Crous) Crous, Slippers & A.J.L. Phillips comb. nov., Neofusicoccum vitifusiforme (Niekerk & Crous) Crous, Slippers & A.J.L. Phillips comb. nov., Neoscytalidium Crous & Slippers gen. nov., Neoscytalidium dimidiatum (Penz.) Crous & Slippers comb. nov., Pseudofusicoccum (Mohali, Slippers & M.J. Wingf.) Mohali, Slippers & M.J. Wingf. gen. nov., Pseudofusicoccum stromaticum