During an investigation into southern pine decline at Fort Benning Georgia, the possibility of wild pigs (Sus scrofa) as an inciting factor became evident. Their rooting activity caused significant root damage on sites showing symptoms of pine decline. It was thought that perhaps the pigs may be moving around pathogenic fungi during their rooting activity in Pinus taeda (loblolly pine) stands. In 2008 and 2010, fungal isolates were obtained from the snouts of wild pigs captured from these stands, as well as, from root-feeding bark beetles and roots sampled 2003-2005. Micromorphology and DNA sequences of the ITS, elongation factor, and beta-tubulin gene regions were employed to identify the fungi recovered. Two new Ophiostoma species and a new Leptographium species were recovered. This study shows that wild pigs may exacerbate pine decline in this location by predisposing trees to bark beetles by reducing tree vigor when causing wounds for soil-borne or insect vectored pathogen infection and perhaps incidentally vectoring plant or tree pathogens during rooting activity.

HomePlant DiseaseVol. 100, No. 7First Report of Laurel Wilt, Caused by Raffaelea lauricola, on Redbay (Persea borbonia) in Texas PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Laurel Wilt, Caused by Raffaelea lauricola, on Redbay (Persea borbonia) in TexasR. D. Menard, S. R. Clarke, S. W. Fraedrich, and T. C. HarringtonR. D. Menard, S. R. Clarke, S. W. Fraedrich, and T. C. HarringtonAffiliationsAuthors and Affiliations R. D. Menard , US Forest Service, Forest Health Protection, Pineville, LA 71360 S. R. Clarke , US Forest Service, Forestry Health Protection, Lufkin, TX 75901 S. W. Fraedrich , US Forest Service, Forestry Sciences Laboratory, Athens, GA 30602 T. C. Harrington , Department of Plant Pathology and Microbiology, Iowa State University, Ames 50011. Published Online:5 May 2016https://doi.org/10.1094/PDIS-01-16-0038-PDNAboutSections ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat Laurel wilt, caused by Raffaelea lauricola T.C.Harr., Aghayeva, & Fraedrich, a fungal symbiont of the redbay ambrosia beetle (Xyleborus glabratus Eichhoff), is responsible for extensive mortality of redbay (Persea borbonia (L.) Spreng) and other Lauraceae native to the United States (Fraedrich et al. 2008). The beetle and fungus were introduced into the United States near Savannah, GA, from Asia around 2000, and since then the disease has been spreading rapidly through the southern United States. In March 2015 dead and dying redbay trees were observed in Hardin County, TX, in an area southwest of Lumberton (30.22404° N; 94.23572° W). The trees exhibited wilt-like symptoms (i.e., limp and dead leaves, and streaks of black discoloration in the xylem) and small insect entrance holes characteristic of X. glabratus. Samples of the discolored wood were plated on malt extract agar (MEA) amended with cycloheximide and streptomycin (CSMA) (Harrington et al. 2010), and a fungus with the unique mucoid growth and budding conidia the size and shape of R. lauricola (Harrington et al. 2008) was routinely isolated. The sequences of a portion of the large subunit (28S) rDNA of eight isolates (C3681-4, C3690-3, Iowa State Univ.) from symptomatic trees were identical to that of all other U.S. isolates of R. lauricola (GenBank Accession No. EU123077) (Harrington et al. 2008). For each of two isolates, three container-grown redbay saplings (165-cm mean height, 1.6-cm mean diameter at groundline) were inoculated with MEA plugs containing mycelium and conidia (Fraedrich et al. 2008). Three additional redbay saplings were mock inoculated with sterile, MEA plugs, and all plants were placed in a growth chamber at 28°C/25°C (day/night) with a 15-h photoperiod. Inoculated plants began to exhibit wilt symptoms within 11 days, and at 28 days all inoculated plants had xylem discoloration and completely wilted. Control plants remained healthy and had no discolored xylem. Pieces of sapwood from 15 cm above the inoculation points were plated on CSMA, and colonies with the unique mucoid growth and budding conidia of R. lauricola were recovered from all wilted plants but not from control plants. A survey for symptomatic trees was conducted in areas around Lumberton in May 2015, and the pathogen was isolated from wilted redbay trees at three additional locations in Hardin and Jasper counties, ranging from 3 to 23 km west and northwest of the original location. The vector was routinely captured in Lindgren traps with cubeb oil lures at several sites around Lumberton. The discovery of laurel wilt in Texas represents another major jump in the distribution of this disease, approximately 300 km to the southwest from Ruston, LA, and 530 km to the west of a five-county-area in southern Mississippi (Laurel Wilt Infestation Map, http://www.fs.usda.gov/main/r8/forest-grasslandhealth). The vector may have been transported with air currents, or moved with infested timber, firewood, or wood chips. Hardin and Jasper counties have forest product mills, similar to other areas of satellite outbreaks found far from the advancing front of the disease (Bates et al. 2013; Fraedrich et al. 2015). Laurel wilt and X. glabratus are now within 550 km of the Mexico border, which has an abundance of native species in the Lauraceae and major avocado plantings.References:Bates, C., et al. 2013. Plant Dis. 97:688. https://doi.org/10.1094/PDIS-09-12-0866-PDN Link, ISI, Google ScholarFraedrich, S. W., et al. 2008. Plant Dis. 92:215. https://doi.org/10.1094/PDIS-92-2-0215 Link, ISI, Google ScholarFraedrich, S. W., et al. 2015. Fla. Entomol. 98:1266. https://doi.org/10.1653/024.098.0445 Crossref, ISI, Google ScholarHarrington, T. C., et al. 2008. Mycotaxon 104:339. Google ScholarHarrington, T. C., et al. 2010. Mycotaxon 111:337. https://doi.org/10.5248/111.337 Crossref, ISI, Google ScholarDetailsFiguresLiterature CitedRelated Vol. 100, No. 7 July 2016SubscribeISSN:0191-2917e-ISSN:1943-7692 Metrics Article History Issue Date: 7 Jun 2016Published: 5 May 2016First Look: 1 Mar 2016Accepted: 23 Feb 2016 Page: 1502 Information© 2016 The American Phytopathological SocietyCited byLaurel wilt susceptibility of three avocado (Persea americana Mill.) ecotypes in relation to xylem anatomy, sap flow and leaf gas exchange22 June 2022 | Trees, Vol. 36, No. 5Raffaelea lauricola (laurel wilt)CABI Compendium, Vol. CABI CompendiumXyleborus glabratus (redbay ambrosia beetle)CABI Compendium, Vol. CABI CompendiumA Diagnostic Guide for Laurel Wilt Disease in AvocadoMonica Navia-Urrutia, Laura Sánchez-Pinzón, Pedro Pablo Parra, and Romina Gazis15 September 2022 | Plant Health Progress, Vol. 23, No. 3Disease severity and ecophysiology of rootstock/scion combinations of different avocado (Persea americana Mill.) genotypes in response to laurel wiltScientia Horticulturae, Vol. 287Sap flow, xylem anatomy and photosynthetic variables of three Persea species in response to laurel wilt20 October 2020 | Tree Physiology, Vol. 41, No. 6Laurel Wilt: Current and Potential Impacts and Possibilities for Prevention and Management4 February 2021 | Forests, Vol. 12, No. 2Rapid Detection of Raffaelea lauricola Directly from Host Plant and Beetle Vector Tissues Using Loop-Mediated Isothermal AmplificationJeffrey L. Hamilton, J. Noah Workman, Campbell J. Nairn, Stephen W. Fraedrich, and Caterina Villari20 October 2020 | Plant Disease, Vol. 104, No. 12High efficiency transformation and mutant screening of the laurel wilt pathogen, Raffaelea lauricola12 July 2020 | Applied Microbiology and Biotechnology, Vol. 104, No. 17An Acaromyces Species Associated with Bark Beetles from Southern Pine Has Inhibitory Properties Against Raffaelea lauricola, the Causal Pathogen of Laurel Wilt Disease of RedbayRabiu Olatinwo and Stephen Fraedrich26 September 2019 | Plant Health Progress, Vol. 20, No. 4Distribution of the Invasive Redbay Ambrosia Beetle Xyleborus glabratus In Southeastern Texas9 July 2018 | The Southwestern Naturalist, Vol. 62, No. 4Genetic Variation in Native Populations of the Laurel Wilt Pathogen, Raffaelea lauricola, in Taiwan and Japan and the Introduced Population in the United StatesCaroline E. Wuest, Thomas C. Harrington, Stephen W. Fraedrich, Hye-Young Yun, and Sheng-Shan Lu8 February 2017 | Plant Disease, Vol. 101, No. 4Status of Sassafras albidum (Nutt.) Nees in the Presence of Laurel Wilt Disease and Throughout the Eastern United StatesSoutheastern Naturalist, Vol. 16, No. 1

Xyleborus glabratus Eichhoff (Coleoptera: Curculionidae: Scolytinae) and sassafras trees that died from laurel wilt were discovered in a 3-parish area of northern Louisiana, USA, in Sep 2014. Redbay, a species that has been severely affected by the disease in the coastal plains forests of the southeastern USA, is not found in this area of northern Louisiana, suggesting that sassafras is attractive to X. glabratus and an adequate reproductive host for the beetle. This is the first report of X. glabratus and laurel wilt in Louisiana and the first report of the beetle and disease west of the Mississippi River. Sumario En septiembre del 2014, Xyleborus glabratus Eichhoff (Coleoptera: Curculionidae: Scolytinae) y arboles de sasafras que murieron a causa de la marchitez del laurel fueron descubiertos en un area de 3 municipios del norte de Louisiana, EE.UU. El aguacatillo ( Persea borbonia ), una especie que se ha visto gravemente afectada por la enfermedad en los bosques de la llanura costero del sudeste de EE.UU., no se encuentra en esta zona del norte de Louisiana, lo que sugiere que el sasafras es atractivo para X. glabratus y un hospedero reproductivo adecuado para el escarabajo. Este es el primer informe de X. glabratus y la marchitez del laurel en Louisiana y el primer informe del escarabajo y la enfermedad al oeste del rio Mississippi. View this article in BioOne

Root feeding bark beetles in the genus Hylastes Hylastes breeding in loblolly pine across 3 crown (Coleoptera: Curculionidae: Scolytinae) commoncondition classes (healthy, dying, dead). Addition ly carry ophiostomatoid fungi (Ophistomatales: ally, the relationship between ophiostomatoid Ophistomataceae)and collectively contribute to species, their Hylastes species vectors, and tree root disorders of Pinus species around the world condition were investigated. (Jacobs & Wingfield 2001). One of the most damLoblolly pine stands across central Alabama aging root disorders is black-stain root disease have experienced high mortality rates, character of conifers in the Western United States, caused ized by scattered stand mortality with a distinct by the fungal species Leptographium wageneri lack of above-ground pests (Brown & McDowell Kendrick and its primary beetle vector H. nig1968). During an investigation of one stand in rinus (Mannerheim) (Witcosky et al. 1986). ReMay 2008 in central Alabama, dying trees were cently, Hylastes salebrosus Eichhoff and H. tenuis found to be infested with root-inhabiting beetles Eichhoff have been associated with loblolly pine and their associated ophiostomatoid fungi. Six (Pinus taeda L.) decline (Eckhardt et al. 2007), trees were selected based on crown condition, in which is considered an emerging forest health iseluding 2 with green, healthy crowns (healthy), sue in the southeastern United States (Eckhardt 2 with severely chlorotic and thinning crowns et al. 2010). (dying), and 2 with red crowns (dead). Two pri Loblolly pine decline (LPD) is a tree disease mary lateral roots were randomly selected and complex that is characterized by symptoms that excavated to approximately 3 meters from the include thinning tree crowns, growth reductions root collar. Roots were removed from trees and (Eckhardt et al. 2007) and premature mortality in carefully dissected. All insects, including imma localized areas (Brown and McDowell 1968). Eviture stages, were collected from roots and adult dence suggests the complex is the result of interbeetles were identified to species. Root tissue was acting abiotic (Eckhardt & Menard 2008) and biobtained from each brood gallery for the isolation otic (Eckhardt et al. 2007) stress factors. Hylastes of ophiostomatoid fungal species using methods species vector a variety of root-infecting ophiostodescribed in Eckhardt et al. (2007). Following matoid fungi (Klebzig et al. 1991, 1995; Eckhardt surface sterilization, tissue was placed on CSMA et al. 2007; Zanzot et al. 2010) which are patho(malt extract agar containing 800 mg/L of cyclo genic to loblolly pine (Matusick & Eckhardt 2010; heximide and 200 mg/1 of streptomycin sulfate) Matusick et al. 2011). Hylastes beetles and their selective nutrient agar (Jacobs & Wingfield 2001). associated fungi are thought to collectively contribEach adult insect was also rolled on CSMA to re ute to LPD by causing root damage through fungal cover ophiostomatoid fungi from insect bodies infection and insect feeding (Eckhardt et al. 2007). (Zanzot et al. 2010). Isolated ophiostomatoid fun Root and lower stem feeding beetle species (Colegal species were identified using morphological optera: Curculionidae) includingH. salebrosus and characters and established keys. Unknown iso H. tenuis are found in increased numbers within lates were sequenced and confirmed as new spe LPD-affected stands, compared to healthy stands cies by M. Wingfield (Forestry and Agricultural (Eckhardt et al. 2007, Menard 2007). A recent Biotechnology Institute, Pretoria, South Africa), study has found Hylastes to be the most common A total of 157 adult beetles (Coleoptera: Cur bark beetle genus observed in loblolly pine stands culionidae) were collected from roots, most from in central Alabama (Thompson 2011), illustrating dying trees (Table 1). A majority of the beetles col their dominance in this ecosystem. Despite their lected were Hylastes species, including a total of dominance and potential for damage in loblolly 113 H. salebrosus (all from dying trees) and 34 pine, the breeding behavior of Hylastes species in H. tenuis (31 from dying and 3 from dead trees), the southeastern United States is not well underIn addition, H. salebrosus larvae and pupae were stood. In the current study, observational methcollected from dying trees. Other adult insect spe ods were used to investigate the potential for cies collected include the black turpentine beetle

SummaryAs a means of exploring pine resistance to root disease and declines, the effects of host plant secondary metabolites on the growth of root colonizing fungi associated with three diseases/declines of southern pines – loblolly pine decline, littleleaf disease and annosum root rot were tested. The associated fungi –Leptographium huntii, L. serpens, L. terebrantis, L. procerum, Heterobasidion annosum and Phytophthora cinnamomi– were grown in saturated atmospheres or in direct contact with, pure monoterpenes and crude oleoresin collected from the four southern pines (Pinus taeda, P. eschinata, P. palustris and P. elliotti) for 7 day. Fungal growth was measured at 3, 5 and 7 day. Root‐infecting fungi differed significantly in sensitivity to crude oleoresin and pure monoterpenes. All fungi tested were inhibited, to some extent, by the resins tested. H. annosum and P. cinnamomi were strongly inhibited by all the monoterpenes tested. The ophiostomatoid fungi were significantly less affected by the compounds tested. L. huntii and L. serpens were less inhibited by monoterpenes than either L. terebrantis or L. procerum. These fungal growth studies show that the kind and amount of secondary metabolite produced by the host plant have a profound effect on tree pathogens. Alterations of tree physiology may have implications for defenses against tree pathogens as well as to the ecology and management of forest ecosystems. Difference in incidence of root disease observed in the field may be explained by the ability of the fungus to tolerate these host defense mechanisms.

Loblolly pine (Pinus taeda L.) decline has been present in upland sites of central Alabama since the 1960s. Symptoms of loblolly pine decline (fine root deterioration, short chlorotic needles, sparse crowns, reduced radial growth) begin in the 30–40 year age class, resulting in premature death at ages 35–50. Loblolly pine decline occurs on sandy, well-drained soils and is associated with Leptographium spp., as well as with root-feeding bark beetles and weevils. The present article discusses the results of a comparison of biological factors associated with pine decline and topographical features, using the analysis of tree health at the Talladega National Forest and Westervelt (formerly Gulf State Paper) Company in central Alabama. Results of this study suggest that an ecological pattern of tree decline and mortality exists. Loblolly stands were more prone to develop symptoms at sites with increased slope and south/southwest orientation. This report indicates that the dominant determinants, or predictors, of loblolly decline are identifiable topographical features.

Loblolly pine decline, characterized by an expanding area of declining and dead trees, is becoming increasingly prevalent in loblolly pine (Pinus taeda L.) forests in central Alabama. A 3-year study was conducted to determine the fungal, root, and lower stem-infesting insect, and/or soil parameters associated with this decline. Hylastes salebrosus, Hylastes tenuis, Pachylobius picivorus, and Hylobius pales were significantly more abundant in declining plots than in asymptomatic plots. Root- and lower stem-infesting insects consistently carried Leptographium terebrantis, L. procerum, and L. serpens. Sampled roots had high levels of root damage, mortality, and staining typically associated with Leptographium species. Root damage and mortality preceded aboveground symptoms of short chlorotic needles, sparse crowns, reduced radial growth, and tree mortality. A sequence of biotic and abiotic factors is proposed as the cause of loblolly pine decline complex.

By the early 1960s over 1.9 million acres of pine plantations had been established on private lands in the south as a result of both the Conservation Reserve Program and an increase in industrial forest management in the region. Because of its rapid growth and ease of establishment, loblolly pine (Pinus taeda L.) quickly became the commercial tree species of choice for southern forestry. However, as time passed, reports of declining loblolly health began to be reported throughout Alabama and the South. Symptoms included trees with short, yellow-green needles, sparse crowns, and reduced radial growth at approximately 40-50 years of age. Mortality usually occurred two to three years after symptoms appeared. Early recommendations were to reduce rotation age of loblolly pine from 70 to 60 years on these sites, maintain a basal area of 60-70 square feet per acre, and convert these stands to longleaf pine (Pinus palustris Mill.), the historic tree species in much of the area. Pine decline, or die-back, continues to impact forest stands. Loblolly pine is currently planted on 80 percent of all southern pine plantations, and is the primary forest type on almost 7 million acres of forestland acres in Alabama. Therefore it is very important that landowners are aware of symptoms and causes of pine stand decline, as well as management options, should their pine stand begin to show signs of decline. Although there are many factors that can affect forest tree health, declines have been associated with soil and weather conditions, deterioration of fine roots, root-feeding insects, and the presence of fungi such as Leptographium spp. in the primary roots. Fire history, previous agricultural practices, lower vegetation density, and landform are factors that are also associated with declining trees.