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Stephen W Fraedrich - One of the best experts on this subject based on the ideXlab platform.

  • Genomic comparisons of the laurel wilt pathogen, Raffaelea lauricola, and related tree pathogens highlight an arsenal of pathogenicity related genes.
    Fungal genetics and biology : FG & B, 2019
    Co-Authors: Jorge Ibarra Caballero, Stephen W Fraedrich, Jongbum Jeon, Yong-hwan Lee, Ned B. Klopfenstein, Mee-sook Kim, Jane E. Stewart
    Abstract:

    Raffaelea lauricola is an invasive fungal pathogen and symbiont of the redbay ambrosia beetle (Xyleborus glabratus) that has caused widespread mortality to redbay (Persea borbonia) and other Lauraceae species in the southeastern USA. We compare two genomes of R. lauricola (C2646 and RL570) to seven other related Ophiostomatales species including R. aguacate (nonpathogenic close relative of R. lauricola), R. quercus-mongolicae (associated with mortality of oaks in Korea), R. quercivora (associated with mortality of oaks in Japan), Grosmannia clavigera (cause of blue stain in conifers), Ophiostoma novo-ulmi (extremely virulent causal agent of Dutch elm disease), O. ulmi (moderately virulent pathogen that cause of Dutch elm disease), and O. piceae (blue-stain saprophyte of conifer logs and lumber). Structural and functional annotations were performed to determine genes that are potentially associated with disease development. Raffaelea lauricola and R. aguacate had the largest genomes, along with the largest number of protein-coding genes, genes encoding secreted proteins, small-secreted proteins, ABC transporters, cytochrome P450 enzymes, CAZYmes, and proteases. Our results indicate that this large genome size was not related to pathogenicity but was likely lineage specific, as the other pathogens in Raffaelea (R. quercus-mongolicae and R. quercivora) had similar genome characteristics to the Ophiostoma species. A diverse repertoire of wood-decaying enzymes were identified in each of the genomes, likely used for toxin neutralization rather than wood degradation. Lastly, a larger number of species-specific, secondary metabolite, synthesis clusters were identified in R. lauricola suggesting that it is well equipped as a pathogen, which could explain its success as a pathogen of a wide range of lauraceous hosts.

  • genetic variation in native populations of the laurel wilt pathogen Raffaelea lauricola in taiwan and japan and the introduced population in the united states
    Plant Disease, 2017
    Co-Authors: Caroline E Wuest, Thomas C. Harrington, Stephen W Fraedrich, Hye Young Yun
    Abstract:

    Laurel wilt is a vascular wilt disease caused by Raffaelea lauricola, a mycangial symbiont of an ambrosia beetle, Xyleborus glabratus. The fungus and vector are native to Asia but were apparently introduced to the Savannah, GA, area 15 or more years ago. Laurel wilt has caused widespread mortality on redbay (Persea borbonia) and other members of the Lauraceae in the southeastern United States, and the pathogen and vector have spread as far as Texas. Although believed to be a single introduction, there has been no extensive study on genetic variation of R. lauricola populations that would suggest a genetic bottleneck in the United States. Ten isolates of R. lauricola from Japan, 55 from Taiwan, and 125 from the United States were analyzed with microsatellite and 28S rDNA markers, and with primers developed for two mating-type genes. The new primers identified isolates as either MAT1 or MAT2 mating types in roughly equal proportions in Taiwan and Japan, where there was also high genetic diversity within pop...

  • xyleborus glabratus attacks and systemic colonization by Raffaelea lauricola associated with dieback of cinnamomum camphora in the southeastern united states
    Forest Pathology, 2015
    Co-Authors: Stephen W Fraedrich, Thomas C. Harrington, G S Best
    Abstract:

    Summary Laurel wilt, caused by Raffaelea lauricola, is responsible for extensive mortality of redbay and other American members of the Lauraceae in the southeastern United States. Raffaelea lauricola is a mycangial symbiont of the redbay ambrosia beetle (Xyleborus glabratus), and the beetle and fungus were accidentally introduced from Asia. Branch dieback of camphortree (Cinnamomum camphora), an Asian member of the Lauraceae, has been occasionally observed in areas where laurel wilt has decimated redbay populations, and R. lauricola was isolated from such camphortrees. However, the role of X. glabratus and R. lauricola in this branch dieback remains unclear. Examination of camphortrees on Jekyll Island, Georgia showed that healthy-appearing trees and those with branch dieback had been attacked by X. glabratus, but the trees with branch dieback had four times as many beetle attacks. Raffaelea lauricola was routinely isolated from discoloured xylem near beetle tunnels in healthy trees and those with dieback. Single-point inoculations with R. lauricola on stems of mature, healthy camphortree trees failed to induce wilt-like symptoms or branch dieback, although areas of discoloration were scattered throughout the xylem, and R. lauricola was reisolated irregularly at various heights in some inoculated trees. In growth chamber experiments, single-point inoculations with R. lauricola resulted in systemic colonization but no wilt symptoms or branch dieback in camphortree saplings. In contrast, inoculations at multiple points along the stem (simulating multiple attacks by the vector) caused branch dieback and wilt-like symptoms, including a brownish, diffuse discoloration of the xylem. Camphortree appears to be more resistant than American species of Lauraceae to the vascular wilt caused by R. lauricola. The fungus does colonize camphortrees systemically, however, and can apparently cause branch dieback. This suggests that the fungus may provide brood material for X. glabratus in Asia as it does in the southeastern United States.

  • first report of laurel wilt caused by Raffaelea lauricola on sassafras sassafras albidum in alabama
    Plant Disease, 2013
    Co-Authors: Rabiu Olatinwo, C Barton, Wood Johnson, Stephen W Fraedrich, J. Hwang
    Abstract:

    Laurel wilt, caused by Raffaelea lauricola, a fungal symbiont of the redbay ambrosia beetle, Xyleborus glabratus, is responsible for extensive mortality of native redbays (Persea borbonia and P. palustris) in the coastal plains of the southeastern United States (1). The wilt also affects the more widespread sassafras, Sassafras albidum, particularly in areas where diseased redbays are common and populations of X. glabratus are high. Because sassafras stems were thought to lack chemicals that are attractive to the beetle, and sassafras tends to be widely scattered in forests, it was believed that the advance of the laurel wilt epidemic front might slow once it reached the edge of the natural range of redbay, which is restricted to the coastal plains of the Gulf and Atlantic Coasts (2). In July and August of 2011, wilt-like symptoms (i.e., wilted and dead leaves, and streaks of black discoloration in the xylem) were observed on 1 to 10 sassafras trees (15 to 23 cm diameter; 6 to 9 m height) at each of three...

  • first report of laurel wilt caused by Raffaelea lauricola on sassafras in mississippi
    Plant Disease, 2011
    Co-Authors: John J Riggins, Stephen W Fraedrich, Thomas C. Harrington
    Abstract:

    Laurel wilt is caused by the fungus Raffaelea lauricola T.C. Harrin., Aghayeva & Fraedrich and is lethal to redbay (Persea borbonia (L.) Spreng.), sassafras (Sassafras albidum (Nutt.) Nees), and other species in the Lauraceae (1). The fungus is carried by the redbay ambrosia beetle (Xyleborus glabratus Eichh.), which is native to Asia. After being discovered in Georgia in 2002 (1), X. glabratus and R. lauricola have spread rapidly, causing extensive redbay mortality in South Carolina, Georgia, Florida, and Mississippi (1,4). The disease has also been confirmed on sassafras in Florida, South Carolina (1), and Georgia. Questions remain as to whether laurel wilt will continue to spread on sassafras, which often occurs as scattered trees in the eastern United States. In June 2010, a homeowner reported that a sassafras tree north of Van Cleave, MS (30.668°N, 88.686°W) had begun wilting in late May. This landscape tree had three 10-m high stems (~20 cm in diameter at breast height). Dark staining in the xylem was observed around the entire circumference of all three stems and nearly all leaves were bronze colored and wilted. No ambrosia beetle tunnels were observed in the stems. No other symptomatic Lauraceae were encountered in the wooded area within 300 m. The nearest known location with laurel wilt on redbay was ~15 km away (4). A Lindgren funnel trap baited with manuka oil (2) was placed at the site in June and monitored biweekly until November, but no X. glabratus adults were captured. Chips from discolored xylem of the sassafras were surface sterilized, plated on cycloheximide-streptomycin malt agar, and R. lauricola was readily isolated (1). Identity of the fungus (isolate C2792 in collection of T. Harrington) was confirmed by using partial sequences of the 28S rDNA (3). The sassafras sequence was identical to that of all known sequences of R. lauricola in the United States, including GenBank No. EU123076 (the holotype isolate from redbay). To confirm pathogenicity, isolate C2792 was grown on malt extract agar and three redbay (average: 141 cm high and 12 mm in diameter at soil interface) and three sassafras (average: 170 cm high and 17 mm in diameter at soil interface) potted plants were wound inoculated with 0.2 ml of a spore suspension (4.9 × 106 conidia/ml) (1). Three control plants of each species were inoculated with sterile deionized water. After 8 weeks in a growth chamber at 26°C, all inoculated redbay and sassafras plants exhibited xylem discoloration above and below the inoculation point, two of the redbay and two of the sassafras had died, and the other plant of each species exhibited partial wilt (the main terminal or one or more branches). All control plants were asymptomatic. R. lauricola was reisolated from all inoculated symptomatic plants but not from controls. To our knowledge, this is the first report of laurel wilt on sassafras in Mississippi. Both redbay (4) and sassafras appear to be highly susceptible to the disease as it moves westward. Sassafras is less attractive than redbay to X. glabratus and it was thought that this might contribute to slowing the spread of laurel wilt once outside the range of redbay (2). Nonetheless, our observations confirm that sassafras can be infected where laurel wilt on redbay is not in the immediate vicinity. References: (1) S. W. Fraedrich et al. Plant Dis. 92:215, 2008. (2) J. L. Hanula et al. J. Econ. Entomol. 101:1276, 2008. (3) T. C. Harrington et al. Mycotaxon 111:337, 2010. (4) J. J. Riggins et al. Plant Dis. 94:634, 2010.

Thomas C. Harrington - One of the best experts on this subject based on the ideXlab platform.

  • genetic variation in native populations of the laurel wilt pathogen Raffaelea lauricola in taiwan and japan and the introduced population in the united states
    Plant Disease, 2017
    Co-Authors: Caroline E Wuest, Thomas C. Harrington, Stephen W Fraedrich, Hye Young Yun
    Abstract:

    Laurel wilt is a vascular wilt disease caused by Raffaelea lauricola, a mycangial symbiont of an ambrosia beetle, Xyleborus glabratus. The fungus and vector are native to Asia but were apparently introduced to the Savannah, GA, area 15 or more years ago. Laurel wilt has caused widespread mortality on redbay (Persea borbonia) and other members of the Lauraceae in the southeastern United States, and the pathogen and vector have spread as far as Texas. Although believed to be a single introduction, there has been no extensive study on genetic variation of R. lauricola populations that would suggest a genetic bottleneck in the United States. Ten isolates of R. lauricola from Japan, 55 from Taiwan, and 125 from the United States were analyzed with microsatellite and 28S rDNA markers, and with primers developed for two mating-type genes. The new primers identified isolates as either MAT1 or MAT2 mating types in roughly equal proportions in Taiwan and Japan, where there was also high genetic diversity within pop...

  • xyleborus glabratus attacks and systemic colonization by Raffaelea lauricola associated with dieback of cinnamomum camphora in the southeastern united states
    Forest Pathology, 2015
    Co-Authors: Stephen W Fraedrich, Thomas C. Harrington, G S Best
    Abstract:

    Summary Laurel wilt, caused by Raffaelea lauricola, is responsible for extensive mortality of redbay and other American members of the Lauraceae in the southeastern United States. Raffaelea lauricola is a mycangial symbiont of the redbay ambrosia beetle (Xyleborus glabratus), and the beetle and fungus were accidentally introduced from Asia. Branch dieback of camphortree (Cinnamomum camphora), an Asian member of the Lauraceae, has been occasionally observed in areas where laurel wilt has decimated redbay populations, and R. lauricola was isolated from such camphortrees. However, the role of X. glabratus and R. lauricola in this branch dieback remains unclear. Examination of camphortrees on Jekyll Island, Georgia showed that healthy-appearing trees and those with branch dieback had been attacked by X. glabratus, but the trees with branch dieback had four times as many beetle attacks. Raffaelea lauricola was routinely isolated from discoloured xylem near beetle tunnels in healthy trees and those with dieback. Single-point inoculations with R. lauricola on stems of mature, healthy camphortree trees failed to induce wilt-like symptoms or branch dieback, although areas of discoloration were scattered throughout the xylem, and R. lauricola was reisolated irregularly at various heights in some inoculated trees. In growth chamber experiments, single-point inoculations with R. lauricola resulted in systemic colonization but no wilt symptoms or branch dieback in camphortree saplings. In contrast, inoculations at multiple points along the stem (simulating multiple attacks by the vector) caused branch dieback and wilt-like symptoms, including a brownish, diffuse discoloration of the xylem. Camphortree appears to be more resistant than American species of Lauraceae to the vascular wilt caused by R. lauricola. The fungus does colonize camphortrees systemically, however, and can apparently cause branch dieback. This suggests that the fungus may provide brood material for X. glabratus in Asia as it does in the southeastern United States.

  • first report of laurel wilt caused by Raffaelea lauricola on sassafras in mississippi
    Plant Disease, 2011
    Co-Authors: John J Riggins, Stephen W Fraedrich, Thomas C. Harrington
    Abstract:

    Laurel wilt is caused by the fungus Raffaelea lauricola T.C. Harrin., Aghayeva & Fraedrich and is lethal to redbay (Persea borbonia (L.) Spreng.), sassafras (Sassafras albidum (Nutt.) Nees), and other species in the Lauraceae (1). The fungus is carried by the redbay ambrosia beetle (Xyleborus glabratus Eichh.), which is native to Asia. After being discovered in Georgia in 2002 (1), X. glabratus and R. lauricola have spread rapidly, causing extensive redbay mortality in South Carolina, Georgia, Florida, and Mississippi (1,4). The disease has also been confirmed on sassafras in Florida, South Carolina (1), and Georgia. Questions remain as to whether laurel wilt will continue to spread on sassafras, which often occurs as scattered trees in the eastern United States. In June 2010, a homeowner reported that a sassafras tree north of Van Cleave, MS (30.668°N, 88.686°W) had begun wilting in late May. This landscape tree had three 10-m high stems (~20 cm in diameter at breast height). Dark staining in the xylem was observed around the entire circumference of all three stems and nearly all leaves were bronze colored and wilted. No ambrosia beetle tunnels were observed in the stems. No other symptomatic Lauraceae were encountered in the wooded area within 300 m. The nearest known location with laurel wilt on redbay was ~15 km away (4). A Lindgren funnel trap baited with manuka oil (2) was placed at the site in June and monitored biweekly until November, but no X. glabratus adults were captured. Chips from discolored xylem of the sassafras were surface sterilized, plated on cycloheximide-streptomycin malt agar, and R. lauricola was readily isolated (1). Identity of the fungus (isolate C2792 in collection of T. Harrington) was confirmed by using partial sequences of the 28S rDNA (3). The sassafras sequence was identical to that of all known sequences of R. lauricola in the United States, including GenBank No. EU123076 (the holotype isolate from redbay). To confirm pathogenicity, isolate C2792 was grown on malt extract agar and three redbay (average: 141 cm high and 12 mm in diameter at soil interface) and three sassafras (average: 170 cm high and 17 mm in diameter at soil interface) potted plants were wound inoculated with 0.2 ml of a spore suspension (4.9 × 106 conidia/ml) (1). Three control plants of each species were inoculated with sterile deionized water. After 8 weeks in a growth chamber at 26°C, all inoculated redbay and sassafras plants exhibited xylem discoloration above and below the inoculation point, two of the redbay and two of the sassafras had died, and the other plant of each species exhibited partial wilt (the main terminal or one or more branches). All control plants were asymptomatic. R. lauricola was reisolated from all inoculated symptomatic plants but not from controls. To our knowledge, this is the first report of laurel wilt on sassafras in Mississippi. Both redbay (4) and sassafras appear to be highly susceptible to the disease as it moves westward. Sassafras is less attractive than redbay to X. glabratus and it was thought that this might contribute to slowing the spread of laurel wilt once outside the range of redbay (2). Nonetheless, our observations confirm that sassafras can be infected where laurel wilt on redbay is not in the immediate vicinity. References: (1) S. W. Fraedrich et al. Plant Dis. 92:215, 2008. (2) J. L. Hanula et al. J. Econ. Entomol. 101:1276, 2008. (3) T. C. Harrington et al. Mycotaxon 111:337, 2010. (4) J. J. Riggins et al. Plant Dis. 94:634, 2010.

  • isolations from the redbay ambrosia beetle xyleborus glabratus confirm that the laurel wilt pathogen Raffaelea lauricola originated in asia
    Mycologia, 2011
    Co-Authors: Thomas C. Harrington, Hideaki Goto, Dilzara N Aghayeva, Hye Young Yun, Stephen W Fraedrich
    Abstract:

    The laurel wilt pathogen Raffaelea laur- icola was hypothesized to have been introduced to the southeastern USA in the mycangium of the redbay ambrosia beetle, Xyleborus glabratus, which is native to Asia. To test this hypothesis adult X. glabratus were trapped in Taiwan and on Kyushu Island, Japan, in 2009, and dead beetles were sent to USA for isolation of fungal symbionts. Individual X. glabratus were macerated in glass tissue grinders, and the slurry was serially diluted and plated onto malt agar medium amended with cycloheximide, a medium semiselec- tive for Ophiostoma species and their anamorphs, including members of Raffaelea. R. lauricola was isolated from 56 of 85 beetles in Taiwan and 10 of 16 beetles in Japan at up to an estimated 10 000 CFUs per beetle. The next most commonly isolated species was R. ellipticospora, which also has been recovered from X. glabratus trapped in the USA, as were two other fungi isolated from beetles in Taiwan, R. fusca and R. subfusca. Three unidentified Raffaelea spp. and three unidentified Ophiostoma spp. were isolated rarely from X. glabratus collected in Taiwan. Isola- tions from beetles similarly trapped in Georgia, USA, yielded R. lauricola and R. ellipticospora in numbers similar to those from beetles trapped in Taiwan and Japan. The results support the hypothesis that R. lauricola

  • short title Raffaelea lauricola wilt pathogen isolations from the redbay ambrosia beetle xyleborus glabratus confirm that the laurel wilt pathogen Raffaelea lauricola originated in asia
    2011
    Co-Authors: Thomas C. Harrington, Hye Young Yun, Dilzara N Aghayeva
    Abstract:

    Isolations from the redbay ambrosia beetle, Xyleborus glabratus, confirm that the laurel wilt pathogen Raffaelea lauricola originated in Asia Thomas C. Harrington Hye Young Yun Department of Plant Pathology, 351 Bessey Hall, Iowa State University, Ames, Iowa 50011 Sheng-Shan Lu Division of Forest Protection, Taiwan Forestry Research Institute, 53 Nanhai Road, Taipei 10066, Taiwan Hideaki Goto Forestry and Forest Products Research Institute, Kyushu Research Center, Kurokami 4-11-16, 860-0862, Japan Dilzara N. Aghayeva Institute of Botany, Azerbaijan National Academy of Sciences, Badamdar 40, Baku AZ1073, Azerbaijan Stephen W. Fraedrich Southern Research Station, USDA Forest Service, Athens, Georgia 30605 Abstract: The laurel wilt pathogen Raffaelea lauricola was hypothesized to have been introduced to the southeastern USA in the mycangium of the redbay ambrosia beetle, Xyleborus glabratus, which is native to Asia. To test this hypothesis adult X. glabratus were trapped in Taiwan and on Kyushu Island, Japan, in 2009, and dead beetles were sent to USA for isolation of fungal symbionts. Individual X. glabratus were macerated in glass tissue grinders, and the slurry was serially diluted and plated onto malt agar medium amended with cycloheximide, a medium In Press at Mycologia, published on April 6, 2011 as doi:10.3852/10-417

R C Ploetz - One of the best experts on this subject based on the ideXlab platform.

  • Nutritional symbionts of a putative vector, Xyleborus bispinatus, of the laurel wilt pathogen of avocado, Raffaelea lauricola
    Symbiosis, 2018
    Co-Authors: J. R. Saucedo, R C Ploetz, J. L. Konkol, M. Ángel, J. Mantilla, O. Menocal, D. Carrillo
    Abstract:

    Ambrosia beetles subsist on fungal symbionts that they carry to, and cultivate in, their natal galleries. These symbionts are usually saprobes, but some are phytopathogens. Very few ambrosial symbioses have been studied closely, and little is known about roles that phytopathogenic symbionts play in the life cycles of these beetles. One of the latter symbionts, Raffaelea lauricola , causes laurel wilt of avocado, Persea americana , but its original ambrosia beetle partner, Xyleborus glabratus , plays an uncertain role in this pathosystem. We examined the response of a putative, alternative vector of R. lauricola , Xyleborus bispinatus , to artificial diets of R. lauricola and other ambrosia fungi. Newly eclosed, unfertilized females of X . bispinatus were reared in no-choice assays on one of five different symbionts or no symbiont. Xyleborus bispinatus developed successfully on R. lauricola , R. arxii , R. subalba and R. subfusca , all of which had been previously recovered from field-collected females of X. bispinatus . However, no development was observed in the absence of a symbiont or on another symbiont, Ambrosiella roeperi , recovered from another ambrosia beetle, Xylosandrus crassiusculus . In the no-choice assays, mycangia of foundress females of X. bispinatus harbored significant colony-forming units of, and natal galleries that they produced were colonized with, the respective Raffaelea symbionts; with each of these fungi, reproduction, fecundity and survival of the beetle were positively impacted. However, no fungus was recovered from, and reproduction did not occur on, the A. roeperi and no symbiont diets. These results highlight the flexible nature of the ambrosial symbiosis, which for X . bispinatus includes a fungus with which it has no evolutionary history. Although the “primary” symbiont of the neotropical X . bispinatus is unclear, it is not the Asian R . lauricola .

  • presence and prevalence of Raffaelea lauricola cause of laurel wilt in different species of ambrosia beetle in florida usa
    Journal of Economic Entomology, 2017
    Co-Authors: R C Ploetz, Rita E Duncan, Daniel Carrillo, Alina Campbell, J. L. Konkol, Julio Mantilla, Teresa I Narvaez, Ramon J Saucedo, Paul E Kendra
    Abstract:

    We summarize the information available on ambrosia beetle species that have been associated in Florida with Raffaelea lauricola T.C. Harr., Fraedrich & Aghayeva, the primary symbiont of Xyleborus glabratus Eichhoff and cause of laurel wilt. In total, 14 species in Ambrosiodmus, Euwallacea, Premnobius, Xyleborus, Xyleborinus, and Xylosandrus were either reared from laurel wilt-affected host trees or trapped in laurel wilt-affected stands of the same, and assayed for R. lauricola. In six collections from native species in the southeastern United States [Persea borbonia (L.), Persea palustris (Raf.) Sarg., and Persea humilis Nash] and four from avocado (Persea americana Mill.), extracted mycangia or heads (taxa with mandibular mycangia) or intact bodies (taxa with mycangia in other locations) were surface-disinfested before assays on a semi-selective medium for the isolation of Raffaelea (CSMA+). Raffaelea lauricola was identified based on its characteristic phenotype on CSMA+, and the identity of a random subset of isolates was confirmed with taxon-specific microsatellite markers. The pathogen was recovered from 34% (246 of 726) of the individuals that were associated with the native Persea spp., but only 6% (58 of 931) of those that were associated with avocado. Over all studies, R. lauricola was recovered from 10 of the ambrosia beetle species, but it was most prevalent in Xyleborus congeners. This is the first record of R. lauricola in Ambrosiodmus lecontei Hopkins, Xyleborinus andrewesi (Blandford), and Xyleborus bispinatus Eichhoff. The potential effects of R. lauricola's promiscuity are discussed.

  • management of laurel wilt of avocado caused by Raffaelea lauricola
    European Journal of Plant Pathology, 2017
    Co-Authors: R C Ploetz, J. L. Konkol, Jose M Perezmartinez, R Fernandez
    Abstract:

    Laurel wilt is caused by Raffaelea lauricola, a nutritional symbiont of an Asian ambrosia beetle, Xyleborus glabratus. American members of the Lauraceae plant family are most susceptible and 300 million trees have been killed by the disease in the southeastern USA since 2003. Recently, commercial production of an important crop in the laurel family, avocado (Persea americana), has been affected in southern Florida. We summarize studies in which diverse measures were tested for managing the disease. In all studies, trees were treated with potential laurel wilt control measures and subsequently inoculated with R. lauricola. On potted plants in greenhouse experiments, commercial nutritional products (Greenstim and Keyplex 350) and SAR products (Agri-Fos and Nutri-Phite), when applied as soil drenches or foliar sprays, had either no impact on, or increased laurel wilt symptom development compared to non-treated control treatments. Bark applications of Tilt (a propiconazole fungicide for which emergency registration had been obtained in 2010) in a surfactant (Pentrabark) enabled significant laurel wilt protection in greenhouse studies on small potted plants, but Pentrabark and other surfactants moved little propiconazole into the xylem of fruit-bearing trees in field studies. In efficacy studies in the field, Propiconazole Pro (an injectable formulation of propiconazole), Tilt, and two experimental formulations of another triazole fungicide, tebuconazole, decreased the development of laurel wilt compared to nontreated control trees when applied as undiluted injections into branches and scaffold limbs (microinjection), or injection of dilute fungicide into tree flare roots (macroinfusion). However, symptoms developed in all treated trees by 10–11 months after inoculation with R. lauricola, indicating that trees would need to be re-treated at least on an annual basis. Regardless of how fungicides were applied, insignificant levels of different active ingredients entered fruit. Although fungicide treatment of fruit-bearing avocado trees is not a concern for food safety and several triazole and DMI fungicides can protect avocado trees from laurel wilt, cost-effective measures with which the xylem could be loaded with and protected by these products remains a challenge. Management of laurel wilt in commercial avocado production areas is discussed.

  • response of swamp bay persea palustris and redbay p borbonia to Raffaelea spp isolated from xyleborus glabratus
    Forest Pathology, 2017
    Co-Authors: Alina Campbell, T. J. Dreaden, R C Ploetz, Carlos A Gonzalezbenecke, Jason A. Smith
    Abstract:

    Summary Laurel wilt is a devastating invasive disease of members of the Lauraceae plant family. It is caused by the fungus Raffaelea lauricola, which is a nutritional symbiont of its ambrosia beetle vector, Xyleborus glabratus. In the United States, six Raffaelea spp., in addition to R. lauricola, have been recovered from mycangia of X. glabratus. We compared the response of two laurel wilt suspects, swamp bay (Persea palustris) and redbay (Persea borbonia), to five of these species, another undescribed Raffaelea sp., and R. lauricola. Six weeks after inoculation, only R. lauricola caused significantly greater symptoms than water inoculations. The fungi varied in their ability to move systemically and be recovered from the host at the end of the experiment. Stem hydraulic conductivity was decreased by R. lauricola, but none of the other taxa. Although the roles these fungi play in the life cycle of X. glabratus are not known, they do not appear to be pathogens on these host tree species.

  • geographic variation in mycangial communities of xyleborus glabratus
    Mycologia, 2016
    Co-Authors: Alina Campbell, T. J. Dreaden, Paul E Kendra, R C Ploetz, Wayne S Montgomery
    Abstract:

    Factors that influence fungal communities in ambrosia beetle mycangia are poorly understood. The beetle that is responsible for spreading laurel wilt in SE USA, Xyleborus glabratrus, was examined at three sites along a 500 km N-S transect in Florida, each populated by host trees in the Lauraceae. Fungal phenotypes were quantified in mycangia of individual females that were collected from a site in Miami-Dade County (MDC), 25.8N, with swamp bay (Persea palustris), one in Highlands County (HC), 27.9N, with silkbay (P. humulis) and swamp bay and another in Alachua County (AC), 29.8N, with redbay (P. borbonia). Based on combined LSU, SSU and beta-tubulin datasets the most prominent phenotypes were Raffaelea lauricola (cause of laurel wilt), R. subalba, R. subfusca, R. fusca, R. arxii and an undescribed Raffaelea sp. Mean numbers of colony forming units (CFUs) of R. lauricola varied by location (P < 0.003), and a multivariate analysis, which accounted for the presence and relative abundance of fungal species, indicated that there were significant variations in mycangial communities among the sites; thus climate and vegetation might have affected fungal diversity and the relative abundance of these fungi in the mycangia of X. glabratus Statistically it was unlikely that any of the species influenced the presence and prevalence of another species.

Jason A. Smith - One of the best experts on this subject based on the ideXlab platform.

  • genomic and transcriptomic insights into Raffaelea lauricola pathogenesis
    BMC Genomics, 2020
    Co-Authors: Yucheng Zhang, Jason A. Smith, Junli Zhang, Dan Vanderpool, Jeffrey A Rollins
    Abstract:

    Laurel wilt caused by Raffaelea lauricola is a lethal vascular disease of North American members of the Lauraceae plant family. This fungus and its primary ambrosia beetle vector Xyleborus glabratus originated from Asia; however, there is no report of laurel wilt causing widespread mortality on native Lauraceae trees in Asia. To gain insight into why R. lauricola is a tree-killing plant pathogen in North America, we generated and compared high quality draft genome assemblies of R. lauricola and its closely related non-pathogenic species R. aguacate. Relative to R. aguacate, the R. lauricola genome uniquely encodes several small-secreted proteins that are associated with virulence in other pathogens and is enriched in secondary metabolite biosynthetic clusters, particularly polyketide synthase (PKS), non-ribosomal peptide synthetase (NRPS) and PKS-NRPS anchored gene clusters. The two species also exhibit significant differences in secreted proteins including CAZymes that are associated with polysaccharide binding including the chitin binding CBM50 (LysM) domain. Transcriptomic comparisons of inoculated redbay trees and in vitro-grown fungal cultures further revealed a number of secreted protein genes, secondary metabolite clusters and alternative sulfur uptake and assimilation pathways that are coordinately up-regulated during infection. Through these comparative analyses we have identified potential adaptations of R. lauricola that may enable it to colonize and cause disease on susceptible hosts. How these adaptations have interacted with co-evolved hosts in Asia, where little to no disease occurs, and non-co-evolved hosts in North America, where lethal wilt occurs, requires additional functional analysis of genes and pathways.

  • response of swamp bay persea palustris and redbay p borbonia to Raffaelea spp isolated from xyleborus glabratus
    Forest Pathology, 2017
    Co-Authors: Alina Campbell, T. J. Dreaden, R C Ploetz, Carlos A Gonzalezbenecke, Jason A. Smith
    Abstract:

    Summary Laurel wilt is a devastating invasive disease of members of the Lauraceae plant family. It is caused by the fungus Raffaelea lauricola, which is a nutritional symbiont of its ambrosia beetle vector, Xyleborus glabratus. In the United States, six Raffaelea spp., in addition to R. lauricola, have been recovered from mycangia of X. glabratus. We compared the response of two laurel wilt suspects, swamp bay (Persea palustris) and redbay (Persea borbonia), to five of these species, another undescribed Raffaelea sp., and R. lauricola. Six weeks after inoculation, only R. lauricola caused significantly greater symptoms than water inoculations. The fungi varied in their ability to move systemically and be recovered from the host at the end of the experiment. Stem hydraulic conductivity was decreased by R. lauricola, but none of the other taxa. Although the roles these fungi play in the life cycle of X. glabratus are not known, they do not appear to be pathogens on these host tree species.

  • phylogeny of ambrosia beetle symbionts in the genus Raffaelea
    Fungal Biology, 2014
    Co-Authors: T. J. Dreaden, Michael J. Wingfield, R C Ploetz, John M Davis, Wilhelm Z De Beer, Pamela S Soltis, Jason A. Smith
    Abstract:

    The genus Raffaelea was established in 1965 when the type species, Raffaelea ambrosia, a symbiont of Platypus ambrosia beetles was described. Since then, many additional ambrosia beetle symbionts have been added to the genus, including the important tree pathogens Raffaelea quercivora, Raffaelea quercus-mongolicae, and Raffaelea lauricola, causal agents of Japanese and Korean oak wilt and laurel wilt, respectively. The discovery of new and the dispersal of described species of Raffaelea to new areas, where they can become invasive, presents challenges for diagnosticians as well as plant protection and quarantine efforts. In this paper, we present the first comprehensive multigene phylogenetic analysis of Raffaelea. As it is currently defined, the genus was found to not be monophyletic. On the basis of this work, Raffaelea sensu stricto is defined and the affinities of undescribed isolates are considered.

  • development of multilocus pcr assays for Raffaelea lauricola causal agent of laurel wilt disease
    Plant Disease, 2014
    Co-Authors: T. J. Dreaden, R C Ploetz, John M Davis, Pamela S Soltis, C L Harmon, A J Palmateer, Jason A. Smith
    Abstract:

    Dreaden, T. J., Davis, J. M., Harmon, C. L., Ploetz, R. C., Palmateer, A. J., Soltis, P. S., and Smith, J. A. 2014. Development of multilocus PCR assays for Raffaelea lauricola, causal agent of laurel wilt disease. Plant Dis. 98:379-383. Laurel wilt, caused by the fungus Raffaelea lauricola, is an exotic disease that affects members of the Lauraceae plant family in the southeastern United States. The disease is spreading rapidly in native forests and is now found in commercial avocado groves in south Florida, where an accurate diagnostic method would improve disease management. A polymerase chain reaction (PCR) method based on amplifying the ribosomal small-subunit DNA, with a detection limit of 0.0001 ng, was found to be suitable for some quantitative PCR applications; however, it was not taxon specific. Genomic sequencing of R. lauricola was used to identify and develop primers to amplify two taxon-specific simple-sequence repeat (SSR) loci, which did not amplify from related taxa or host DNA. The new SSR loci PCR assay has a detection limit of 0.1 ng of R. lauricola DNA, is compatible with traditional and real-time PCR, was tested in four labs to confirm consistency, and reduces diagnostic time from 1 week to 1 day. Our work illustrates pitfalls to designing taxon-specific assays for new pathogens and that undescribed fungi can limit specificity.

  • responses of avocado to laurel wilt caused by Raffaelea lauricola
    Plant Pathology, 2012
    Co-Authors: R C Ploetz, Jason A. Smith, M Hughes, Tyler J Dreaden, Sharon Inch, Jose M Perezmartinez, Y Fu
    Abstract:

    Laurel wilt, caused by Raffaelea lauricola, threatens native and non-native species in the Lauraceae in the south-eastern USA. Avocado, Persea americana, is the most important agricultural suscept of laurel wilt. Grafted plants (clonal scions on seedling rootstocks) of 24 cultivars were screened against the disease in the field from 2008 to 2010. Disease was induced with either mycelial plugs or conidial suspensions of R. lauricola. There were significant differences in the severity of disease that developed on different cultivars, and West Indian cultivars were most susceptible (P <0 AE05). Simmonds, a West Indian cultivar that comprises 35% of the commercial production in Florida, was consistently susceptible and was used as a standard genotype in different studies. Disease severity increased significantly on cv. Simmonds as plant size (stem diameter) increased (P <0 AE0042). In greenhouse studies, internal (sapwood) and external disease severities on cv. Simmonds were correlated (P <0 AE0001), and a threshold was evident, in that external symptoms developed only after moderately severe symptoms had developed internally. Latent infection was uncommon; R. lauricola was usually isolated on a semiselective medium or detected via qPCR only from discoloured xylem of inoculated cv. Simmonds. As basipetal movement of the pathogen was common, its movement among trees via root grafts is probable. Greater understanding is needed of the movement of R. lauricola in naturally and artificially infected trees, and whether sufficient tolerance exists in avocado to assist in the management of this important new disease.

Albert E. Mayfield - One of the best experts on this subject based on the ideXlab platform.

  • North American Lauraceae: Terpenoid Emissions, Relative Attraction and Boring Preferences of Redbay Ambrosia Beetle, Xyleborus glabratus (Coleoptera:
    2016
    Co-Authors: Curculionidae Scolytinae, Paul E Kendra, Wayne S Montgomery, Jerome Niogret, Grechen E. Pruett, Albert E. Mayfield
    Abstract:

    The invasive redbay ambrosia beetle, Xyleborus glabratus, is the primary vector of Raffaelea lauricola, a symbiotic fungus and the etiologic agent of laurel wilt. This lethal disease has caused severe mortality of redbay (Persea borbonia) and swampbay (P. palustris) trees in the southeastern USA, threatens avocado (P. americana) production in Florida, and has potential to impact additional New World species. To date, all North American hosts of X. glabratus and suscepts of laurel wilt are members of the family Lauraceae. This comparative study combined field tests and laboratory bioassays to evaluate attraction and boring preferences of female X. glabratus using freshly-cut bolts from nine species of Lauraceae: avocado (one cultivar of each botanical race), redbay, swampbay, silkbay (Persea humilis), California bay laurel (Umbellularia californica), sassafras (Sassafras albidum), northern spicebush (Lindera benzoin), camphor tree (Cinnamomum camphora), and lancewood (Nectandra coriacea). In addition, volatile collections and gas chromatography-mass spectroscopy (GC-MS) were conducted to quantify terpenoid emissions from test bolts, and electroantennography (EAG) was performed to measur

  • first report of laurel wilt disease caused by Raffaelea lauricola on camphor in florida and georgia
    Plant Disease, 2009
    Co-Authors: Jason A. Smith, Albert E. Mayfield, Lacey L Mount, C Bates, W A Lamborn, Stephen W Fraedrich
    Abstract:

    Laurel wilt is a recently described (1) vascular disease of redbay (Persea borbonia (L.) Spreng) and other plants in the family Lauraceae. The wilt is caused by Raffaelea lauricola, a fungus vectored by the nonnative redbay ambrosia beetle (Xyleborus glabratus Eichhoff) (1,2). Since 2003, laurel wilt has caused widespread mortality of redbay in Georgia, South Carolina, and Florida (1) and has recently been found on avocado in Florida (4). Since June of 2007, wilted shoots and branch dieback have been observed in several camphor trees (Cinnamomum camphora (L.) Sieb.) in residential areas of McIntosh and Glynn counties in Georgia and Baker County in Florida. Symptomatic camphor trees ranged from 4.5 to 12 m high and occurred in areas where redbay mortality due to laurel wilt has been frequently observed during the last 2 to 3 years. In some camphor trees, only the smaller branches (<2 cm in diameter) were wilting or dead, whereas in other trees (e.g., Baker County, Florida), the larger branches and substant...

  • biology and host associations of redbay ambrosia beetle coleoptera curculionidae scolytinae exotic vector of laurel wilt killing redbay trees in the southeastern united states
    Journal of Economic Entomology, 2008
    Co-Authors: James L. Hanula, Stephen W Fraedrich, Albert E. Mayfield, Robert J Rabaglia
    Abstract:

    Abstract The redbay ambrosia beetle, Xyleborus glabratus Eichhoff (Coleoptera: Curculionidae: Scolytinae), and its fungal symbiont, Raffaelea sp., are new introductions to the southeastern United States responsible for the wilt of mature redbay, Persea borbonia (L.) Spreng., trees. In 2006 and 2007, we investigated the seasonal flight activity of X. glabratus, its host associations, and population levels at eight locations in South Carolina and Georgia where infestations ranged from very recent to at least several years old. Adults were active throughout the year with peak activity in early September. Brood development seems to take 50–60 d. Wood infested with beetles and infected with the Raffaelea sp. was similar in attraction to uninfested redbay wood, whereas both were more attractive than a nonhost species. Sassafras, Sassafras albidium (Nutt.) Nees, another species of Lauraceae, was not attractive to X. glabratus and very few beetle entrance holes were found in sassafras wood compared with redbay. C...

  • biology and host associations of redbay ambrosia beetle coleoptera curculionidae scolytinae exotic vector of laurel wilt killing redbay trees in the southeastern united states
    Journal of Economic Entomology, 2008
    Co-Authors: James L. Hanula, Stephen W Fraedrich, Albert E. Mayfield, Robert J Rabaglia
    Abstract:

    The redbay ambrosia beetle, Xyleborus glabratus Eichhoff (Coleoptera: Curculionidae: Scolytinae), and its fungal symbiont, Raffaelea sp., are new introductions to the southeastern United States responsible for the wilt of mature redbay, Persea borbonia (L.) Spreng., trees. In 2006 and 2007, we investigated the seasonal flight activity of X. glabratus, its host associations, and population levels at eight locations in South Carolina and Georgia where infestations ranged from very recent to at least several years old. Adults were active throughout the year with peak activity in early September. Brood development seems to take 50-60 d. Wood infested with beetles and infected with the Raffaelea sp. was similar in attraction to uninfested redbay wood, whereas both were more attractive than a nonhost species. Sassafras, Sassafras albidium (Nutt.) Nees, another species of Lauraceae, was not attractive to X. glabratus and very few beetle entrance holes were found in sassafras wood compared with redbay. Conversely, avocado, Persea americana Mill., was as attractive to X. glabratus as swampbay, P. palustris (Raf.) Sarg., and both were more attractive than the nonhost red maple, Acer rubrum L. However, avocado had relatively few entrance holes in the wood. In 2007, we compared X. glabratus populations in areas where all mature redbay have died to areas where infestations were very active and more recent. Trap catches of X. glabratus and numbers of entrance holes in trap bolts of redbay were correlated with the number of dead trees with leaves attached. Older infestations where mature host trees had been eliminated by the wilt had low numbers of beetles resulting in trap catches ranging from 0.04 to 0.12 beetles per trap per d compared with 4-7 beetles per trap per d in areas with numerous recently dead trees. Our results indicate beetle populations drop dramatically after suitable host material is gone and provide hope that management strategies can be developed to restore redbay trees. The lack of attraction of X. glabratus to sassafras suggests that spread of X. glabratus may slow once it is outside the range of redbay.

  • first report of laurel wilt disease caused by a Raffaelea sp on avocado in florida
    Plant Disease, 2008
    Co-Authors: Albert E. Mayfield, Jason A. Smith, M Hughes, Tyler J Dreaden
    Abstract:

    Laurel wilt is a vascular disease of redbay (Persea borbonia (L.) Spreng.) and other plants in the family Lauraceae in the southeastern United States. It is caused by a fungus (Raffaelea sp.) that is vectored by a non-native insect of Asian origin, the redbay ambrosia beetle (Xyleborus glabratus Eichhoff) (1). Since the initial detection of the redbay ambrosia beetle near Savannah, GA in 2002, laurel wilt has caused widespread mortality of redbay in Georgia, South Carolina, and Florida (1). In September 2007, an avocado (Persea americana Mill.) tree planted approximately 10 years earlier in a residential neighborhood in Jacksonville, FL was discovered to be infected with laurel wilt. The crown was in various stages of decline, including upper branches that were dead and leafless, those with wilted and drooping foliage, and those with healthy foliage. Removal of bark from wilted branch sections revealed black-to-brown streaks of discoloration in the sapwood and a few ambrosia beetle holes from which the di...