First Report of Hiemalis begonias Wilt Disease Caused by Fusarium foetens in Canada

Hiemalis begonias Fotsch (Begonia × hiemalis), a member of the family Begoniaceae, is a commercially important potted flowering plant in Europe and North America. In the spring of 2010, stunted growth and dull green leaves of H. begonias were observed in a commercial greenhouse in southern Ontario, Canada. Symptoms began with dull green foliage, followed by wilted leaves, then the stem base became water soaked with vascular discoloration, and finally, large macroconidial masses of a fungus developed on the collapsed stems and veins. A fungus was consistently isolated from the leaves, stems, and roots of symptomatic plants. Single conidia were isolated from sporodochia and cultured on potato dextrose agar (PDA) and oatmeal agar (OA) for 7 days. Isolates exhibited strong pungent odors on PDA and OA and a brownish orange colony on OA and a light orange colony on PDA. Masses of light orange and hemispherical-shaped conidia and stromata formed on OA. Conidiophores formed from aerial mycelium producing ellipsoidal microconidia without septation. Sporodochia formed on agar surface producing three-septate, slightly curved macroconidia. The cultural and conidial characteristics of the isolates were similar to those of Fusarium foetens Schroers (4). Partial translation elongation factor 1-α (TEF) gene was amplified and sequenced with primers ef1 and ef2. A comparison of a partial sequence has been deposited in GenBank (Accession No. HM748968) and showed a 100% match with F. foetens (2). Inoculations with F. foetens isolates were performed by injecting a 100-μl suspension of 1 × 106 conidia/ml into stems of five healthy plants near the ground or soaking the soil of five healthy 6-week-old H. begonias cv. Golden Edith with 50 ml of suspension. Control plants were similarly injected with sterile water or sown in sterile soil. After 4 weeks, all inoculated plants developed dark, wilting leaves and collapsed stems and veins similar to those observed in the commercial greenhouse. F. foetens was reisolated from diseased plants, and identification was reconfirmed by conidial characteristics and TEF 1-α sequence. Control plants were healthy and symptom free. F. foetens has recently been described in association with a new disease of H. begonias in Europe (3) and the United States (1). F. foetens can cause major economic losses to farmers and marketers of H. begonias in Europe and the United States. To our knowledge, this is the first report of F. foetens causing wilt disease of H. begonias in Canada. References: (1) W.-H. Elmer et al. Plant Dis. 88:1287, 2004. (2) D.-M. Geiser et al. Eur. J. Plant Pathol. 110:473, 2004. (3) R. Schrage. Phytomed. Ges. 33:68, 2003. (4) H.-J. Schroers et al. Mycologia 96:393, 2004.

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First Report of a Wilt Disease of Hiemalis Begonias Caused by Fusarium foetens in the United States

Plant Disease ◽

10.1094/pdis.2004.88.11.1287b ◽

2004 ◽

Vol 88 (11) ◽

pp. 1287-1287 ◽

Cited By ~ 10

Author(s):

W. H. Elmer ◽

C. Vossbrinck ◽

D. M. Geiser

Keyword(s):

Elongation Factor ◽

Aerial Mycelium ◽

The United States ◽

Wilt Disease ◽

Potato Dextrose Agar ◽

State University ◽

Rare Occurrence ◽

Pennsylvania State University ◽

Fusarium Spp ◽

Fusarium Foetens

During 2003, 10% of the Hiemalis begonias (Begonia × hiemalis Fotsch) developed wilt symptoms in a commercial greenhouse in Connecticut. Foliage turned a dull green, and stems developed a dark watersoaked discoloration near the soil line and had vascular discoloration. Stems, petioles, and leaves collapsed and became covered with sporodochia of a Fusarium spp. Single conidia were isolated from sporodochia and cultured on carnation leaf agar (CLA) and potato dextrose agar for 10 days. Isolates resembled Fusarium oxysporum, but the profuse sporulation with minimal aerial mycelium and the rare occurrence of polyphialides was consistent with the description of F. foetens (2). A comparison of a partial sequence of the 1-α elongation factor gene showed a 100% match with F. foetens. Inocula from five isolates were grown on CLA, washed from the plate, and adjusted to 106 conidia per ml. Suspension (50 μl) was injected into stems of healthy 6-week-old Hiemalis begonias cv. Barkos (one plant per isolate). Controls received distilled water. After 4 weeks, all inoculated plants turned dark and collapsed, and the same fungus was reisolated from these plants. Control stems remained healthy. An isolate (O-2348) has been deposited at the Fusarium Research Center at Pennsylvania State University, University Park. F. foetens has recently been described in association with a new disease of Hiemalis begonias in Europe (1). References: (1) R. Schrage, Phytomedizinischen Gesellschaft 33:68, 2003. (2) H.-J. Schroers et al. Mycologia 96:393, 2004.

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First Report of Impatiens Downy Mildew Outbreaks Caused by Plasmopara obducens Throughout the Hawai'ian Islands

Plant Disease ◽

10.1094/pdis-10-13-1017-pdn ◽

2014 ◽

Vol 98 (5) ◽

pp. 696-696 ◽

Cited By ~ 7

Author(s):

J. A. Crouch ◽

M. P. Ko ◽

J. M. McKemy

Keyword(s):

United States ◽

Downy Mildew ◽

The United States ◽

Molecular Data ◽

Economic Losses ◽

Voucher Specimen ◽

First Report ◽

Plastic Bags ◽

Leaf Surfaces ◽

Impatiens Walleriana

Downy mildew of impatiens (Impatiens walleriana Hook.f.) was first reported from the continental United States in 2004. In 2011 to 2012, severe and widespread outbreaks were documented across the United States mainland, resulting in considerable economic losses. On May 5, 2013, downy mildew disease symptoms were observed from I. walleriana ‘Super Elfin’ at a retail nursery in Mililani, on the Hawai'ian island of Oahu. Throughout May and June 2013, additional sightings of the disease were documented from the islands of Oahu, Kauai, Maui, and Hawai'i from nurseries, home gardens, and botanical park and landscape plantings. Symptoms of infected plants initially showed downward leaf curl, followed by a stippled chlorotic appearance on the adaxial leaf surfaces. Abaxial leaf surfaces were covered with a layer of white mycelia. Affected plants exhibited defoliation, flower drop, and stem rot as the disease progressed. Based on morphological and molecular data, the organism was identified as Plasmopara obducens (J. Schröt.) J. Schröt. Microscopic observation disclosed coenocytic mycelium and hyaline, thin-walled, tree-like (monopodial branches), straight, 94.0 to 300.0 × 3.2 to 10.8 μm sporangiophores. Ovoid, hyaline sporangia measuring 11.0 to 14.6 × 12.2 to 16.2 (average 13.2 × 14.7) μm were borne on sterigma tips of rigid branchlets (8.0 to 15.0 μm) at right angle to the main axis of the sporangiophores (1,3). Molecular identification of the pathogen was conducted by removing hyphae from the surface of three heavily infected leaves using sterile tweezers, then extracting DNA using the QIAGEN Plant DNA kit (QIAGEN, Gaithersburg, MD). The nuclear rDNA internal transcribed spacer was sequenced from each of the three samples bidirectionally from Illustra EXOStar (GE Healthcare, Piscataway, NJ) purified amplicon generated from primers ITS1-O and LR-0R (4). Resultant sequences (GenBank KF366378 to 80) shared 99 to 100% nucleotide identity with P. obducens accession DQ665666 (4). A voucher specimen (BPI892676) was deposited in the U.S. National Fungus Collections, Beltsville, MD. Pathogenicity tests were performed by spraying 6-week-old impatiens plants (I. walleriana var. Super Elfin) grown singly in 4-inch pots with a suspension of 1 × 104 P. obducens sporangia/ml until runoff using a handheld atomizer. Control plants were sprayed with distilled water. The plants were kept in high humidity by covering with black plastic bags for 48 h at 20°C, and then maintained in the greenhouse (night/day temperature of 20/24°C). The first symptoms (downward curling and chlorotic stippling of leaves) and sporulation of the pathogen on under-leaf surfaces of the inoculated plants appeared at 10 days and 21 days after inoculation, respectively. Control plants remained healthy. Morphological features and measurements matched those of the original inoculum, thus fulfilling Koch's postulates. To our knowledge, this is the first report of downy mildew on I. walleriana in Hawai'i (2). The disease appears to be widespread throughout the islands and is likely to cause considerable losses in Hawai'ian landscapes and production settings. References: (1) O. Constantinescu. Mycologia 83:473, 1991. (2) D. F. Farr and A. Y. Rossman. Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ July 16, 2013. (3) P. A. Saccardo. Syllogue Fungorum 7:242, 1888. (4) M. Thines. Fungal Genet Biol 44:199, 2007.

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First Report of Okra yellow mosaic Mexico virus in Okra in the United States

Plant Disease ◽

10.1094/pdis-94-7-0924b ◽

2010 ◽

Vol 94 (7) ◽

pp. 924-924 ◽

Cited By ~ 7

Author(s):

C. Hernandez-Zepeda ◽

T. Isakeit ◽

A. Scott ◽

J. K. Brown

Keyword(s):

United States ◽

The United States ◽

Full Length ◽

Bipartite Begomoviruses ◽

Economic Losses ◽

Growth Stages ◽

First Report ◽

Total Dna ◽

Hidalgo County ◽

Whitefly Vector

During the okra growing season from August to November of 2009, symptoms reminiscent of geminivirus infection were observed on 75% of ‘Green Emerald’ Abelmoschus esculentus (L.) Moench, plants in a 0.2-km2 field in Hidalgo County, TX. Visible symptoms consisted of irregular yellow patches on leaves, distinctive yellow borders on leaf edges, and chlorosis of subsequently developing leaves. The whitefly vector of begomoviruses, Bemisia tabaci (Genn.), infested okra plants in the early growth stages during late July 2009. Total DNA was isolated from the leaves of three symptomatic okra plant samples (1) and used as the PCR template to amplify a 575-bp fragment of the coat protein gene (CP) using the universal begomovirus primers AV494 and AC1048 (2). PCR products of the expected size were cloned into the pGEM-T Easy (Promega, Madison, WI) and sequenced using the universal M13F and M13 R primers. ClustalV alignment indicated 99 to 100% shared nucleotide (nt) identity, and BLAST analysis revealed that the closest relative was Okra yellow mosaic Mexico virus - Tetekalitla (OkYMMV) (GenBank Accession No. EF591631) at 98%. To amplify the full-length DNA-A and a possible cognate DNA-B component, one plant that was positive by CP-PCR and DNA sequencing was selected for further analysis. Total DNA from this plant was used as template for a second detection method that consisted of rolling circle amplification (RCA) using the TempliPhi 100 Amplification System (GE Healthcare). RCA is a non-sequence-specific approach that permits amplification of circular DNA. The RCA products were linearized to release unit length ~2.6 kb DNA-A and DNA-B components using BamHI, and EcoRI, respectively. These products were cloned into pGEM3zf+ (Promega) and sequenced using M13F and M13 R primers and then by primer walking (>300 base overlap). Full-length DNA-A and DNA-B components were obtained, respectively, at 2,613 bp (GenBank Accession No. HM035059) and 2,594 bp (GenBank Accession No HM035060). Alignment of the DNA-A component using ClustalV (MegAlign, DNASTAR, Madison, WI) with begomoviral sequences available in GenBank indicated that it was 99% identical to OkYMMV DNA-A (GenBank Accession No. DQ022611). The closest relative to the DNA-B component (ClustalV) was Sida golden mosaic virus (SiGMV) (GenBank Accession No. AJ250731) at 73%. The nt identity of the 172-nt ‘common region’ present in the DNA-A and DNA-B components was 99%, and the iterons (predicted Rep binding motif) were identical for the two components, indicating that they are a cognate pair. The genome organization was typical of other New World bipartite begomoviruses. The economic losses due to infection by this virus could not be determined because an early freeze killed the plants. Hidalgo County is adjacent to Tamaulipas, Mexico, where ~50 km2 of okra are grown and the whitefly vector is also present. The identification of OkYMMV based on two independent detection methods, and the presence of begomovirus-like symptoms together with the whitefly vector, provide robust evidence for the association of OkYMMV-TX with diseased okra plants. To our knowledge, this is the first report of OkYMMV-TX infecting okra crops in Texas and in the continental United States. References: (1) J. J. Doyle and J. L. Doyle. Focus 12:13, 1990. (2) S. Wyatt and J. K. Brown. Phytopathology 86:1288, 1996.

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First Report of Cytospora punicae Causing Wood Canker and Branch Dieback of Pomegranate (Punica granatum) in the United States

Plant Disease ◽

10.1094/pdis-11-13-1133-pdn ◽

2014 ◽

Vol 98 (6) ◽

pp. 853-853 ◽

Cited By ~ 5

Author(s):

F. Peduto Hand ◽

R. A. Choudhury ◽

W. D. Gubler

Keyword(s):

United States ◽

Elongation Factor ◽

Punica Granatum ◽

The United States ◽

Internal Transcribed Spacer Region ◽

Intermittent Light ◽

First Report ◽

Consensus Sequences ◽

Vascular Discoloration ◽

Branch Dieback

Pomegranates (Punica granatum L.) are an expanding industry in the United States with California growing approximately 32,000 acres with a crop value of over $155 million (1). During June and July of 2012, we observed severe limb and branch dieback in pomegranate orchards cv. Wonderful located in Contra Costa, Kings, and Kern counties of California. Disease symptoms included yellowing of leaves, branch and limb dieback, wood lesions, and canker formation. Dark brown Cytospora-like cultures were consistently isolated from active cankers on potato dextrose agar (PDA) amended with 100 mg l−1 tetracycline hydrochloride. Three isolates (UCCE1223, UCCE1233, and UCCE1234) representative of each orchard were sub-cultured onto PDA and incubated at 22°C under fluorescent intermittent light (12 h light, 12 h dark). Fungal colonies had whitish mycelia that turned olive green to dark brown with maturity and formed globose and dark brown pycnidia after 12 days. Conidia were hyaline, aseptate, allantoid, and (4) 4.5 to 5 (6) × (1) 1.5 (2) μm (n = 180). Pycnidia formed in culture measured (250) 350 to 475 (650) μm in diameter (n = 40). Identification of the isolates was confirmed by sequence comparison of the internal transcribed spacer region (ITS1-5.8S-ITS2) of the rDNA and part of the translation elongation factor 1-α gene (EF1-α) with sequences available in GenBank. Consensus sequences of both genes of all isolates showed 99% homology to the species Cytospora punicae Sacc. (2). All sequences were deposited in GenBank (Accession Nos. KJ621684 to 89). Pathogenicity of the isolates was determined by branch inoculation. In December 2012, 3-year-old branches of P. granatum cv. Wonderful were inoculated by placing 5-mm-diameter mycelium plugs from the growing margin of 14-day-old PDA cultures in fresh wounds made with a 5-mm-diameter cork-borer. Eight branches per isolate were inoculated on eight different trees. Eight control branches were inoculated with non-colonized PDA agar plugs. Inoculations were covered with Vaseline and wrapped with Parafilm to retain moisture. Branches were harvested in August 2013 and examined for canker development and the extent of vascular discoloration spreading downward and upward from the inoculation point. Isolations from the edge of discolored tissue were conducted to fulfill Koch's postulates. C. punicae was re-isolated from 100% of the inoculated branches. Total length of vascular discoloration averaged 30.2 mm in branches inoculated with the three C. punicae isolates and 9 mm in the control branches. No fungi were isolated from the slightly discolored tissue of the controls. To our knowledge, this is the first report of C. punicae as a fungal trunk pathogen of pomegranate trees in the United States. References: (1) California County Agricultural Commissioners' Data, 2010 Crop Year. USDA NASS California field office, retrieved from http://www.nass.usda.gov/Statistics_by_State/California/ Publications/AgComm/201010cactb00.pdf , 2011. (2) P. A. Saccardo. Sylloge Fungorum 3:256, 1884.

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Fusarium Canker of Bitternut Hickory Caused by Fusarium solani in the North-Central and Northeastern United States

Plant Disease ◽

10.1094/pdis-09-11-0766 ◽

2012 ◽

Vol 96 (3) ◽

pp. 455-455 ◽

Cited By ~ 1

Author(s):

J.-H. Park ◽

J. Juzwik

Keyword(s):

United States ◽

Fusarium Solani ◽

Apical Cell ◽

Elongation Factor ◽

Morphological Characteristics ◽

Aerial Mycelium ◽

The United States ◽

Eastern United States ◽

Gene Sequences ◽

Inner Bark

Multiple annual cankers were observed on the upper main stems of bitternut hickory (Carya cordiformis) exhibiting top dieback in Indiana, Iowa, Minnesota, New York, Ohio, and Wisconsin during a 2006 to 2008 survey of declining hickory. The top-killed trees had normal-sized, green leaves below and the cankers were oval, sunken, and bounded by heavy callus that seemed to arrest further canker expansion. Fusarium solani was consistently isolated from the margins of inner bark lesions or discolored sapwood of the cankers. When cultured on potato dextrose agar, the isolates grew rapidly with abundant aerial mycelium. On carnation leaf agar, thick-walled macroconidia with 4 to 5 septa were produced in cream, blue-green, or blue sporodochia. Macroconidia were generally cylindrical with a blunt or rounded apical cell and a rounded or foot-shaped basal cell. Microconidia were oval to kidney shaped with 0 to 1 septa and were produced in false heads on elongate monophialides. Chlamydospores were formed singly or in pairs. These morphological characteristics are consistent with descriptions of F. solani (2). The identities of 42 representative isolates were confirmed by sequencing the translation elongation factor (tef) 1-α gene. BLAST analysis of the sequences from each isolate against the GenBank and FUSARIUM-ID database found 98 to 100% similarities to F. solani isolates (GenBank Accession Nos. DQ246841, DQ247025, DQ247282, and DQ247436 and FUSARIUM-ID isolate FD01041). Two haplotypes (BB and BC) were distinguished based on the tef 1-α gene sequences that differed by 10 bp. Pathogenicity tests were conducted with two isolates of each haplotype on asymptomatic C. cordiformis (12 to 21 cm in diameter) in forest stands. In May 2009 in Wabasha County, MN, 0.1-ml spore suspensions (1 × 104 macroconidia/ml) or sterile water was placed in one of three holes (0.6 cm in diameter) drilled to the cambium of 12 trees. The holes were sealed with moist cotton and moldable putty. A duplicate trial, but with BB and BC isolates from Wisconsin, was initiated in Chippewa County, WI in June 2009. The extent of inner bark necrosis was assessed 13 months after inoculation in both sites. Inoculations with F. solani in Minnesota resulted in inner bark lesions with average lengths of 20 and 30 mm for the BB and BC haplotypes, respectively. In Wisconsin, BB and BC haplotypes caused inner bark lesions with average lengths of 34 and 38 mm, respectively. While sunken or open cankers were found for all the BC isolate inoculations, relatively small and callus-bounded cankers were found for BB isolate inoculations. All control wounds were callus-closed with average wound lengths of 12 and 23 mm in Minnesota and Wisconsin, respectively. The same haplotype of F. solani used for inoculation was recovered from each canker as confirmed by analysis of tef 1-α gene sequences. F. solani was not obtained from control wounds. To our knowledge, this is the first report of a canker caused by F. solani on bitternut hickory (1). The same fungus has been previously reported to cause cankers on stems of other hardwood tree genera in the eastern United States and Canada. We hypothesize that numerous main-stem cankers caused by F. solani lead to top dieback of bitternut hickory. References: (1) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St. Paul, MN, 1989. (2) J. F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual. Blackwell Publishing, Ames, IA, 2006.

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First Report of Powdery Mildew Caused by Erysiphe cruciferarum on Camelina sativa in Montana

Plant Disease ◽

10.1094/pdis-10-21-2362-pdn ◽

2021 ◽

Author(s):

Benzhong Fu ◽

Qing Yan

Keyword(s):

United States ◽

Powdery Mildew ◽

The United States ◽

Camelina Sativa ◽

Its Sequences ◽

Flowering Plant ◽

Biofuel Crop ◽

First Report ◽

Erysiphe Cruciferarum ◽

Query Cover

Camelina sativa (L.) Crantz, also known as false flax, is an annual flowering plant in the family Brassicaceae and originated in Europe and Asia. In recent years, it is cultivated as an important biofuel crop in Europe, Canada, and the northwest of the United States. In June of 2021, severe powdery mildew was observed on C. sativa ‘Suneson’ plants under greenhouse conditions (temperature 18.3°C/22.2°C, night/day) in Bozeman, Montana (45°40'N, 111°2'W). The disease incidence was 80.67% (150 pots, one plant per pot). White ectophytic powdery mildew including mycelia and conidia were observed on the upper leaves, usually developed from bottom tissues to top parts, also present on stems and siliques. Mycelia on leaves were amphigenous and in patches, often spreading to become effused. These typical symptoms were similar to a previous report of powdery mildew on Broccoli raab (Koike and Saenz 1997). Appressoria are lobed, and foot cells are cylindrical with size 18 to 26 × 7 to 10 μm. Conidia are cylindrical and produced singly, with a size of 35 to 50 × 12 to 21 μm and a length : width ratio greater than two (Koike and Saenz 1997). No chasmothecia were observed under the greenhouse conditions. The symptoms and fungal microscopic characters are typical of Pseudoidium anamorph of Erysiphe (Braun 1995). The specific measurements and characteristics are consistent with previous records of Erysiphe cruciferarum Opiz ex L. Junell (Braun and Cook 2012; Vellios et al. 2017). To identify the pathogen, the partial internal transcribed spacer (ITS) region of rDNA of sample CPD-1 was amplified using primers ITS1 and ITS4 (White et al. 1990). The amplicons were sequenced, and the resulting 559-bp sequence was deposited in GenBank (CPD-1, Accession number: OK160719). A GenBank BLAST search of the ITS sequences showed an exact match (100% query cover, E-value 0, and 100% identity 559/559 bp) with those of E. cruciferarum on hosts Brassica sp. (KY660929.1), B. juncea from Vietnam (KM260718.1) and China (KT957424.1). A phylogenetic tree was generated with the CPD-1 ITS sequence with several of ITS sequences of close species with different hosts obtained from the GenBank. Isolate CPD-1 was grouped with pathogens from Brassica hosts rather than the holotype strain (KU672364.1) from papaveraceous hosts. To fulfill Koch's postulates, pathogenicity was confirmed through inoculation by dusting conidia onto leaves of seven healthy, potted, 14-day-old C. sativa seedlings (cv. Suneson). Seven non-inoculated plants served as a control treatment. The plants were incubated in a greenhouse with a temperature of 18°C (night) to 22°C (day). The inoculated plants developed similar symptoms after 7 days, whereas the control plants remained symptomless. The fungus on the inoculated plants was morphologically identical to that was originally observed on the diseased plants. Though many Brassica spp. have been known to be infected by E. cruciferarum throughout the world, powdery mildew of C. sativa cultivar Crantz in natural conditions by E. cruciferarum has been reported only in the province of Domokos in Central Greece (Vellios et al. 2017). To our knowledge, this is the first report of powdery mildew caused by E. cruciferarum on C. sativa in Montana. Though the powdery mildew on C. sativa was observed in the greenhouse conditions in this work, it poses a potential threat to the production of this biofuel crop in the northwest of the United States.

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First Report of Five Sooty Blotch and Flyspeck Fungi on Prunus americana in the United States

Plant Disease ◽

10.1094/pdis-91-12-1685b ◽

2007 ◽

Vol 91 (12) ◽

pp. 1685-1685 ◽

Cited By ~ 5

Author(s):

J. Latinović ◽

J. C. Batzer ◽

K. B. Duttweiler ◽

M. L. Gleason ◽

G. Sun

Keyword(s):

United States ◽

The United States ◽

Apple Fruit ◽

Economic Losses ◽

Research Station ◽

First Report ◽

Sooty Blotch ◽

Sooty Blotch And Flyspeck ◽

Pcr Products ◽

Pure Cultures

The sooty blotch and flyspeck (SBFS) complex includes more than 30 fungi that blemish the cuticle of apple fruit, causing economic losses in humid regions worldwide (1). In August 2005, we sampled SBFS-infested wild plum (Prunus americana) fruit growing in hedgerows in Iowa. Colonies were categorized according to mycelial type (1), and isolates were made from representative colonies onto acidified water agar (AWA). Plum skins with SBFS signs were excised, pressed, and photographed. DNA was obtained from purified isolates and also from mycelium and fruiting bodies scraped directly from plum fruit skins. Extracted DNA was amplified using primer pair ITS1-F/Myc1-R (ACTCGTCGAAGGAGCTACG) and PCR products were sequenced using primer pair ITS-1F/ITS4. Six sequences were obtained from pure cultures and seven from colonies on plum fruit skin. BLAST analysis of the 470-bp sequences showed 100% homology to five known species in the SBFS complex: Zygophiala cryptogama, Zygophiala wisconsinensis, Pseudocercosporella sp. RH1, and Stomiopeltis spp. RS1 and RS2 (GenBank Accession Nos. AY598854, AY598853, AY5988645, AY598882, and AY598883, respectively). Observations of colony and fruiting structure morphology from cultures on potato dextrose agar (PDA) and colonies on plums confirmed species identity. A modified version of Koch's postulates was conducted to verify that these fungi caused the signs observed on plum and could also infest apple fruit. In June 2006, 1-month-old cultures on PDA were pulverized in a blender with sterile distilled water, passed through four layers of sterile cheesecloth, and transferred to sterile jars. Each isolate was inoculated onto 20 fruit on plum trees (P. americana) on the Iowa State University (ISU) campus and 20 fruit on cv. Golden Delicious apple trees at the ISU Research Station, Gilbert, IA. Each fruit was disinfested with 70% ethanol, air dried, swabbed with inoculum, and covered with a Fuji bag. At harvest, fungal colonies on fruit were reisolated onto AWA. DNA was extracted from pure cultures; when isolations on agar were unsuccessful, DNA was extracted directly from colonies on fruit. PCR was conducted using ITS1-F/Myc1-R, and PCR products were sequenced using ITS1-F/ITS4. All five species were reisolated and sequenced from apple. Pseudocercosporella sp. RH1 and Stomiopeltis sp. RS1 were sequenced from inoculated plums. Although flyspeck, presumably caused by Schizothyrium pomi, was reported on Japanese plum (P. salicina) in Japan (2) and black cherry (P. serotina) in the United States (3), to our knowledge this is the first report of SBFS fungi on plum in the United States and the first confirmation that fungi from plum can produce SBFS signs on apple fruit. Wild plum may therefore act as a reservoir host, providing inoculum for SBFS infestations on apple. References: (1) J. Batzer et al. Mycologia 97:1268, 2005. (2) H. Nasu and H. Kunoh. Plant Dis. 71:361, 1987. (3) T. B. Sutton. Plant Dis. 72:801, 1988.

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First Report of Xanthomonas translucens Causing Wilt Disease on Perennial Ryegrass (Lolium perenne) in the United States

Plant Disease ◽

10.1094/pdis-01-15-0127-pdn ◽

2015 ◽

Vol 99 (9) ◽

pp. 1270-1270 ◽

Cited By ~ 2

Author(s):

P. R. Giordano ◽

Q. Zeng ◽

N. M. Dykema ◽

A. R. Detweiler ◽

J. M. Vargas

Keyword(s):

United States ◽

Lolium Perenne ◽

Perennial Ryegrass ◽

The United States ◽

Wilt Disease ◽

First Report ◽

Xanthomonas Translucens

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First Report of Penicillium expansum Isolates Resistant to Pyrimethanil from Stored Apple Fruit in Pennsylvania

Plant Disease ◽

10.1094/pdis-12-13-1214-pdn ◽

2014 ◽

Vol 98 (7) ◽

pp. 1004-1004 ◽

Cited By ~ 4

Author(s):

H. J. Yan ◽

V. L. Gaskins ◽

I. Vico ◽

Y. G. Luo ◽

W. M. Jurick

Keyword(s):

United States ◽

The United States ◽

Apple Fruit ◽

Washington State ◽

Penicillium Expansum ◽

Economic Losses ◽

Conidial Suspension ◽

Blue Mold ◽

First Report ◽

Penicillium Spp

Apples in the United States are stored in low-temperature controlled atmospheres for 9 to 12 months and are highly susceptible to blue mold decay. Penicillium spp. cause significant economic losses worldwide and produce mycotoxins that contaminate processed apple products. Blue mold is managed by a combination of cultural practices and the application of fungicides. In 2004, a new postharvest fungicide, pyrimethanil (Penbotec 400 SC, Janseen PMP, Beerse, Belgium) was registered for use in the United States to control blue mold on pome fruits (1). In this study, 10 blue mold symptomatic ‘Red Delicious’ apples were collected in May 2011 from wooden bins at a commercial facility located in Pennsylvania. These fruit had been treated with Penbotec prior to controlled atmosphere storage. Ten single-spore Penicillium spp. isolates were analyzed for growth using 96-well microtiter plates containing Richards minimal medium amended with a range of technical grade pyrimethanil from 0 to 500 μg/ml. Conidial suspensions adjusted to 1 × 105 conidia/ml were added to three 96-well plates for each experiment; all experiments were repeated three times. Nine resistant isolates had prolific mycelial growth at 500 μg/ml, which is 1,000 times the discriminatory dose that inhibited baseline sensitive P. expansum isolates from Washington State (1). However, one isolate (R13) had limited conidial germination and no mycelial proliferation at 0.5 μg/ml and was categorized as sensitive. One resistant (R22) and one sensitive (R13) isolate were selected on the basis of their different sensitivities to pyrimethanil. Both isolates were identified as P. expansum via conventional PCR using β-tubulin gene-specific primers according to Sholberg et al. (2). Analysis of the 2X consensus amplicon sequences from R13 and R22 matched perfectly (100% identity and 0.0 E value) with other P. expansum accessions in GenBank including JN872743.1, which was isolated from decayed apple fruit from Washington State. To determine if pyrimethanil applied at the labeled rate of 500 μg/ml would control R13 or R22 in vivo, organic ‘Gala’ apple fruit were wounded, inoculated with 50 μl of a conidial suspension (1 × 104 conidia/ml) of either isolate, dipped in Penbotec fungicide or sterile water, and stored at 25°C for 7 days. Twenty fruit composed a replicate within a treatment and the experiment was performed twice. Non-inoculated water-only controls were symptomless, while water-dipped inoculated fruit had 100% decay with mean lesion diameters of 36.8 ± 2.68 mm for R22 and 38.5 ± 2.61 mm for R13. The R22 isolate caused 30% decay with 21.6 ± 5.44 mm lesions when inoculated onto Penbotec-treated apples, while the R13 isolate had 7.5% decay incidence with mean lesion diameters of 23.1 ± 3.41 mm. The results from this study demonstrate that P. expansum pyrimethanil-resistant strains are virulent on Penbotec-treated apple fruit and have the potential to manifest in decay during storage. To the best of our knowledge, this is the first report of pyrimethanil resistance in P. expansum from Pennsylvania, a major apple growing region for the United States. Moreover, these results illuminate the need to develop additional chemical, cultural, and biological methods to control this fungus. References: (1) H. X. Li and C. L. Xiao. Phytopathology 98:427, 2008. (2) P. L. Sholberg et al. Postharvest Biol. Technol. 36:41, 2005.

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First Report of Fusarium Rot of Garlic Bulbs Caused by Fusarium proliferatum in North Carolina

Plant Disease ◽

10.1094/pdis-01-14-0040-pdn ◽

2014 ◽

Vol 98 (7) ◽

pp. 1009-1009 ◽

Cited By ~ 2

Author(s):

L. M. Quesada-Ocampo ◽

S. Butler ◽

S. Withers ◽

K. Ivors

Keyword(s):

North Carolina ◽

Apical Cell ◽

Elongation Factor ◽

Morphological Characteristics ◽

Aerial Mycelium ◽

The United States ◽

Fusarium Proliferatum ◽

First Report ◽

Its Regions ◽

Dry Conditions

In August of 2013, garlic bulbs (Allium sativum) of the variety Chesnok Red grown and stored under dry conditions by a commercial producer in Buncombe County showed water-soaked, tan to salmon-pink lesions. Lesions on cloves became soft over time, slightly sunken, and had mycelium near the center of the bulb, which is characteristic of Fusarium rots on garlic (1,2). Approximately 10 to 20% of the bulbs inspected in the drying storage room were affected. Surface-sterilized tissue was excised from the margin of lesions on eight bulbs, plated onto acid potato dextrose agar (APDA), and incubated in the dark at room temperature (21°C). White to light pink colonies with abundant aerial mycelium and a purple pigment were obtained from all samples after 2 to 3 days of incubation. Inspection of colony morphology and reproductive structures under a microscope revealed that isolate characteristics were consistent with Fusarium proliferatum (Matsushima) Nirenberg. Microscopic morphological characteristics of the isolate included hyaline, septate hyphae; slender, slightly curved macroconidia with three to five septae produced in sporodochia; curved apical cell; and club-shaped, aseptate microconidia (measuring 3.3 to 8.3 × 1.1 to 1.3 μm) produced in chains by mono and polyphyalides. To further define the identity of the isolate, the beta-tubulin (Btub), elongation factor 1a (EF1a), and internal transcribed spacer (ITS) regions were amplified and sequenced (3). The resulting sequences were compared against the GenBank nucleotide database by using a BLAST alignment, which revealed that the isolate had 100% identity with F. proliferatum for the Btub, EF1a, and ITS regions (GenBank Accession Nos. AF291055.1, JX118976.1, and HF930594.1, respectively). Sequences for the isolate were deposited in GenBank under accessions KJ128963, KJ128964, and KJ128965. While there have been other reports of F. proliferatum causing bulb rot of garlic in the United States (1), to our knowledge, this is the first report in North Carolina. The finding is significant since F. proliferatum can produce a broad range of mycotoxins, including fumonisins, when infecting its host, which is a concern for food safety in Allium crops. References: (1) F. M. Dugan et al. Plant Pathol. 52:426, 2003. (2) L. J. du Toit and F. M. Dugan. Page 15 in: Compendium of Onion and Garlic Diseases and Pests. H. F. Schwartz and S. K. Mohan, eds. The American Phytopathological Society, St. Paul, MN, 2008. (3) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, San Diego, CA, 1990.

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