Copper tolerance in Xanthomonas arboricola pv. pruni in South Carolina peach orchards

Plant Disease ◽  
2021 ◽  
Author(s):  
Brodie Cox ◽  
Hehe Wang ◽  
Guido Schnabel
Keyword(s):  
United States ◽  
South Carolina ◽  
Management Practices ◽  
Southeastern United States ◽  
The United States ◽  
Copper Tolerance ◽  
Bacterial Spot ◽  
Organic Farm ◽  
Xanthomonas Arboricola ◽  
Tolerance To Copper

Bacterial spot of peach, caused by Xanthomonas arboricola pv. pruni (Xap), causes yield loss every year in southeastern United States peach orchards. Management is mainly driven by season-long applications of copper-based products, site location, and choice of cultivar. Although tolerance to copper has not been reported in Xap in the United States, adaptation of populations due to frequent use is a concern. We collected Xap from shoot cankers, leaves, and fruit of cv. O'Henry over two years from three conventional farms and one organic farm in South Carolina, one orchard per farm. The four farms had been using copper extensively for years to control bacterial spot. Xap was isolated from four canker types (bud canker, tip canker, non-concentric canker, and concentric canker) in early spring (‘bud break’), as well as from leaf and fruit tissues later in the season at phenological stages ‘pit hardening’ and ‘final swell’. Xap was most frequently isolated from cankers of the organic farm (24% of the cankers) and most isolates (45%) came from bud cankers. Xap isolates were assessed for sensitivity to copper using minimal glucose yeast agar and nutrient agar amended with 38 µg/ml or 51 µg/ml of Cu2+. Two phenotypes of copper-tolerance in Xap were discovered: low copper tolerance (LCT: growth up to 38 µg/ml Cu2+) and high copper tolerance (HCT: growth up to 51 µg/ml Cu2+). A total of 26 (23 LCT and 3 HCT) out of 165 isolates in 2018 and 32 (20 LCT and 12 HCT) out of 133 isolates in 2019 were tolerant to copper. Peach leaves on potted trees were sprayed with copper rates typically applied at ‘delayed dormancy’ (high rate; 2,397 µg/ml Cu2+), at ‘shuck split’ (medium rate; 599 µg/ml Cu2+), and during ‘summer cover sprays’ (low rate; 120 µg/ml Cu2+) and subsequently inoculated with sensitive, LCT and HCT strains. Results indicated that the low and medium rates of copper reduced bacterial spot incidence caused by the sensitive strain but not by the LCT and HCT strains. This study confirms existence of Xap tolerance to copper in commercial peach orchards in the southeastern United States and suggests its contribution to bacterial spot development under current management practices.

scholarly journals Fungicide Rotation Programs for Managing Phytophthora Fruit Rot of Watermelon in Southeastern United States

2017 ◽  
Vol 18 (1) ◽  
pp. 28-34 ◽  
Author(s):  
Chandrasekar (Shaker) S. Kousik ◽  
Pingsheng Ji ◽  
Daniel S. Egel ◽  
Lina M. Quesada-Ocampo
Keyword(s):  
United States ◽  
South Carolina ◽  
Phytophthora Capsici ◽  
Southeastern United States ◽  
Heavy Rain ◽  
Integrated Approach ◽  
The United States ◽  
Fruit Rot ◽  
Management Options ◽  
Before And After

About 50% of the watermelons in the United States are produced in the southeastern states, where optimal conditions for development of Phytophthora fruit rot prevail. Phytophthora fruit rot significantly limits watermelon production by causing serious yield losses before and after fruit harvest. Efficacy of fungicide rotation programs and Melcast-scheduled sprays for managing Phytophthora fruit rot was determined by conducting experiments in Phytophthora capsici-infested fields at three locations in southeastern United States (North Carolina, South Carolina, and Georgia). The mini seedless cultivar Wonder and seeded cultivar Mickey Lee (pollenizer) were used. Five weekly applications of fungicides were made at all locations. Significant fruit rot (53 to 91%, mean 68%) was observed in the nontreated control plots in all three years (2013 to 2015) and across locations. All fungicide rotation programs significantly reduced Phytophthora fruit rot compared with nontreated controls. Overall, the rotation of Zampro alternated with Orondis was highly effective across three locations and two years. Rotations of Actigard followed by Ranman+Ridomil Gold, Presidio, V-10208, and Orondis, or rotation of Revus alternated with Presidio were similarly effective. Use of Melcast, a melon disease-forecasting tool, may occasionally enable savings of one spray application without significantly impacting control. Although many fungicides are available for use in rotations, under very heavy rain and pathogen pressure, the fungicides alone may not offer adequate protection; therefore, an integrated approach should be used with other management options including well-drained fields.

scholarly journals Structure and Origin of Xanthomonas arboricola pv. pruni Populations Causing Bacterial Spot of Stone Fruit Trees in Western Europe

2005 ◽  
Vol 95 (9) ◽  
pp. 1081-1088 ◽  
Author(s):  
Sylvain Boudon ◽  
Charles Manceau ◽  
Jean-Loup Nottéghem
Keyword(s):  
United States ◽  
Western Europe ◽  
Housekeeping Genes ◽  
Fruit Trees ◽  
The United States ◽  
European Population ◽  
Population Diversity ◽  
Stone Fruit ◽  
Bacterial Spot ◽  
Xanthomonas Arboricola

Xanthomonas arboricola pv. pruni, the causal agent of bacterial spot on stone fruit, was found in 1995 in several orchards in southeastern France. We studied population genetics of this emerging pathogen in comparison with populations from the United States, where the disease was first described, and from Italy, where the disease has occurred since 1920. Four housekeeping genes (atpD, dnaK, efp, and glnA) and the intergenic transcribed spacer region were sequenced from a total of 3.9 kb of sequences, and fluorescent amplified fragment length polymorphism (FAFLP) analysis was performed. A collection of 64 X. arboricola pv. pruni strains, including 23 strains from France, was analyzed. The X. arboricola pv. pruni population had a low diversity because no sequence polymorphisms were observed. Population diversity revealed by FAFLP was lower for the West European population than for the American population. The same bacterial genotype was detected from five countries on three continents, a geographic distribution that can be explained by human-aided migration of bacteria. Our data support the hypothesis that the pathogen originated in the United States and subsequently has been disseminated to other stone-fruit-growing regions of the world. In France, emergence of this disease was due to a recent introduction of the most prevalent genotype of the bacterium found worldwide.

scholarly journals First Report of Resistance to Mefenoxam in Phytophthora cactorum in the United States and Elsewhere

Plant Disease ◽  
2004 ◽  
Vol 88 (5) ◽  
pp. 576-576 ◽  
Author(s):  
S. N. Jeffers ◽  
G. Schnabel ◽  
J. P. Smith
Keyword(s):  
United States ◽  
South Carolina ◽  
Tap Water ◽  
Southeastern United States ◽  
Crop Protection ◽  
The United States ◽  
Crown Rot ◽  
Phytophthora Cactorum ◽  
Mycelium Growth ◽  
First Report

Phytophthora cactorum causes crown rot of strawberry (Fragaria × ananassa) (2), a disease that has been particularly severe during the last 5 years in the southeastern United States. In the fall of 2001, strawberry plants (cv. Camarosa) in a field in Lexington County, South Carolina exhibited typical crown rot symptoms (2) 1 to 2 weeks after transplanting, even though plants had been drenched with mefenoxam (Ridomil Gold; Syngenta Crop Protection, Greensboro, NC) immediately after transplanting. Initially, we observed leaves that had marginal necrosis, were smaller than normal, and were discolored. Soon after, diseased plants appeared stunted and unthrifty compared with other plants in the field, and some of these plants eventually wilted and died. Severely affected plants had necrotic roots and decayed crowns. Ten symptomatic plants were collected for isolation. In the laboratory, root and crown tissues were rinsed in running tap water and blotted dry, small pieces of necrotic tissue were placed aseptically on PAR-V8 selective medium (1), and isolation plates were placed at 20°C in the dark for up to 7 days. P. cactorum was recovered from six plants. Isolates produced characteristic asexual and sexual structures directly on the isolation plates (i.e., papillate sporangia on sympodial sporangiophores and oospores with paragynous antheridia) (2). A single hypha of an isolate from each plant was transferred to fresh PAR-V8, and pure cultures were stored on cornmeal agar in glass vials at 15°C in the dark. All six isolates from the Lexington County field and nine other isolates of P. cactorum from strawberry (three from South Carolina, three from North Carolina, and three from Florida) were tested for sensitivity to mefenoxam on fungicide-amended medium. Mefenoxam was added to 10% clarified V8 juice agar (cV8A) after autoclaving so the concentration in the medium was 100 ppm. Agar plugs from active colonies were transferred to mefenoxam-amended and nonamended cV8A (three replicates per treatment), plates were placed at 25°C in the dark for 3 days, and linear mycelium growth was measured. All six isolates from Lexington County were highly resistant to mefenoxam with mycelium growth relatively unrestricted on mefenoxam-amended medium (73 to 89% of that on nonamended medium). In comparison, the other nine isolates were sensitive to mefenoxam with mycelium growth severely restricted by 100 ppm of mefenoxam (0 to 7% of that on nonamended medium). To our knowledge, this is the first report of mefenoxam resistance in P. cactorum on strawberry or any other crop in the United States and elsewhere. Because mefenoxam is the primary fungicide used to manage Phytophthora crown rot in the southeastern United States, resistance may limit use of this fungicide in strawberry production. References: (1) A. J. Ferguson and S. N. Jeffers. Plant Dis. 83:1129, 1999. (2) E. Seemüller. Crown rot. Pages 50–51 in: Compendium of Strawberry Diseases, 2nd ed. J. L. Maas, ed. The American Phytopathological Society, St. Paul, MN, 1998.

scholarly journals Emergence of Groundnut ringspot virus and Tomato chlorotic spot virus in Vegetables in Florida and the Southeastern United States

2015 ◽  
Vol 105 (3) ◽  
pp. 388-398 ◽  
Author(s):  
Craig G. Webster ◽  
Galen Frantz ◽  
Stuart R. Reitz ◽  
Joseph E. Funderburk ◽  
H. Charles Mellinger ◽  
...  
Keyword(s):  
United States ◽  
New York ◽  
South Carolina ◽  
Southeastern United States ◽  
The United States ◽  
South Florida ◽  
Ringspot Virus ◽  
Spot Virus ◽  
Genomic Rnas ◽  
Chlorotic Spot

Groundnut ringspot virus (GRSV) and Tomato chlorotic spot virus (TCSV) are two emerging tospoviruses in Florida. In a survey of the southeastern United States, GRSV and TCSV were frequently detected in solanaceous crops and weeds with tospovirus-like symptoms in south Florida, and occurred sympatrically with Tomato spotted wilt virus (TSWV) in tomato and pepper in south Florida. TSWV was the only tospovirus detected in other survey locations, with the exceptions of GRSV from tomato (Solanum lycopersicum) in South Carolina and New York, both of which are first reports. Impatiens (Impatiens walleriana) and lettuce (Lactuca sativa) were the only non-solanaceous GRSV and/or TCSV hosts identified in experimental host range studies. Little genetic diversity was observed in GRSV and TCSV sequences, likely due to the recent introductions of both viruses. All GRSV isolates characterized were reassortants with the TCSV M RNA. In laboratory transmission studies, Frankliniella schultzei was a more efficient vector of GRSV than F. occidentalis. TCSV was acquired more efficiently than GRSV by F. occidentalis but upon acquisition, transmission frequencies were similar. Further spread of GRSV and TCSV in the United States is possible and detection of mixed infections highlights the opportunity for additional reassortment of tospovirus genomic RNAs.

scholarly journals Diversity Among Ralstonia solanacearum Strains Isolated from the Southeastern United States

2012 ◽  
Vol 102 (10) ◽  
pp. 924-936 ◽  
Author(s):  
Jason C. Hong ◽  
David J. Norman ◽  
David L. Reed ◽  
M. Timur Momol ◽  
Jeffrey B. Jones
Keyword(s):  
United States ◽  
South Carolina ◽  
Ralstonia Solanacearum ◽  
Phylogenetic Analyses ◽  
Southeastern United States ◽  
The United States ◽  
Hypersensitive Reaction ◽  
Systemic Movement ◽  
Solanacearum Strain ◽  
Unique Banding Pattern

This is the first comprehensive study of a collection of Ralstonia solanacearum strains from the southeastern United States to be characterized based on biovar, pathogenicity, hypersensitive reaction on tobacco, and phylogenetic analyses of the egl sequence. Rigorous phylogenetic analysis of the commonly used egl gene produced robust phylogenies that differed significantly from a neighbor-joining tree differed from and previously published phylogenies for R. solanacearum strains. These robust trees placed phylotype IV within the phylotype I clade, which may suggest that phylogenies based solely on egl may be misleading. As a result of phylogenetic analyses in this study, we determined that U.S. strains from Georgia, North Carolina, South Carolina, and older Florida strains isolated from solanaceous crops all belong to phylotype II sequevar 7. However, many strains recently isolated in Florida from tomato and other crops were more diverse than the southeastern United States population. These unique Florida strains grouped with strains mostly originating from the Caribbean and Central America. One of the exotic strains, which in a previous study was determined to be established in northern Florida, was characterized more extensively. Upon using Musa-specific multiplex polymerase chain reaction, this strain produced a unique banding pattern, which has not previously been reported. Inoculation of this strain into Musa spp. did not result in wilt symptoms; however, the plants were stunted and root masses were significantly reduced. Furthermore, following root inoculation, the bacterium, unlike a typical Florida race 1 biovar 1 strain, was recovered from the roots and stems, indicating systemic movement. This is the first report of an R. solanacearum strain isolated in the United States that is deleterious to the growth of Musa plants.

Black Muslimness Mobilized

2019 ◽  
Vol 36 (1) ◽  
Author(s):  
Youssef J. Carter
Keyword(s):  
United States ◽  
South Carolina ◽  
Religious Study ◽  
The United States ◽  
Black Atlantic ◽  
West African ◽  
Religious Leader ◽  
American Muslims ◽  
The Rich ◽  
Sufi Order

The Mustafawi Tariqa is a transnational Sufi Order that was initiated in 1966 by the late Cheikh Mustafa Gueye Haydara (d. 1989) in Thiès, Senegal. Yet, only since 1994 has this specific Sufi network reached westward across the water, bringing American Muslims—many of whom are converts—into the larger network. In the United States, the majority of students who have entered the Tariqa and have declared allegiance (bayah) to Shaykh Arona Rashid Faye Al-Faqir are African-Americans who have inserted themselves religiously, culturally, and pedagogically into a West African Sufi tradition which emphasizes religious study and the practice of dhikr (remembrance of God). Shaykh Arona Faye is a Senegalese religious leader who relocated to the southeastern region of the United States from West Africa to spread the religion of Islam and expose American Muslims to the rich West African tradition of spiritual purification and Islamic piety. At the same time, many of those who are African-American members of this tradition have made it a point to travel to Senegal themselves to strengthen transatlantic ties with West African compatriots and visit sacred burial sites in the small city of Thiès. I examine how two sites of pilgrimage for the Mustafawi—Moncks Corner, South Carolina and Thiès, Senegal—play a part in the infrastructure of Black Atlantic Sufi network. Moncks Corner is the central site in which access to the Tariqa’s most charismatic living shaykh, Shaykh Arona Faye, has worked for the past two decades teaching and mentoring those on the Path. On the other hand, Thiès is the location where the Tariqa’s founder is buried and travelers visit the town in order to pay homage to his memory. I show how these sites catalyze mobility and operate as spaces of spiritual refuge for visitors in both local and regional contexts by looking at how a local zawiyah produces movement in relation to a broader tariqa. By looking at pilgrimage and knowledge transmission, I argue that the manner in which esoteric approaches to spiritual care and the embodiment of higher Islamic ethics via the West African Sufi methodology of the Mustafawi informs the manner in which Muslims of varying African descent inhabit a broader diasporic identification of “Black Muslimness.”

Hunting the eagle killer: A cyanobacterial neurotoxin causes vacuolar myelinopathy

Science ◽  
2021 ◽  
Vol 371 (6536) ◽  
pp. eaax9050
Author(s):  
Steffen Breinlinger ◽  
Tabitha J. Phillips ◽  
Brigette N. Haram ◽  
Jan Mareš ◽  
José A. Martínez Yerena ◽  
...  
Keyword(s):  
United States ◽  
Aquatic Vegetation ◽  
Southeastern United States ◽  
Hydrilla Verticillata ◽  
Toxin Production ◽  
The United States ◽  
Biosynthetic Gene Cluster ◽  
Biosynthetic Gene ◽  
Bald Eagles ◽  
Cyanobacterial Species

Vacuolar myelinopathy is a fatal neurological disease that was initially discovered during a mysterious mass mortality of bald eagles in Arkansas in the United States. The cause of this wildlife disease has eluded scientists for decades while its occurrence has continued to spread throughout freshwater reservoirs in the southeastern United States. Recent studies have demonstrated that vacuolar myelinopathy is induced by consumption of the epiphytic cyanobacterial species Aetokthonos hydrillicola growing on aquatic vegetation, primarily the invasive Hydrilla verticillata. Here, we describe the identification, biosynthetic gene cluster, and biological activity of aetokthonotoxin, a pentabrominated biindole alkaloid that is produced by the cyanobacterium A. hydrillicola. We identify this cyanobacterial neurotoxin as the causal agent of vacuolar myelinopathy and discuss environmental factors—especially bromide availability—that promote toxin production.

Sign in / Sign up

Export Citation Format

Share Document