First Report of Alternaria alternata Causing Postharvest Decay on Apple Fruit During Cold Storage in Pennsylvania

Alternaria rot, caused by Alternaria alternata (Fr.) Keissl., occurs on apple fruit (Malus × domestica Borkh) worldwide and is not controlled with postharvest fungicides currently registered for apple in the United States (1). Initial infections can occur in the orchard prior to harvest, or during cold storage, and appear as small red dots located around lenticels (1). The symptoms appear on fruits within a 2 month period after placement into cold storage (3). In February 2013, ‘Nittany’ apple fruit with round, dark, dry, spongy lesions were collected from bins at commercial storage facility located in Pennsylvania. Symptomatic apples (n = 2 fruits) were placed on paper trays in an 80 count apple box and immediately transported to the laboratory. Fruit were rinsed with sterile water, and the lesions were superficially disinfected with 70% ethanol. The skin was removed with a sterile scalpel, and tissues underneath the lesion were cultured on potato dextrose agar (PDA) and incubated at 25°C with constant light. Two single-spore isolates were propagated on PDA, and permanent cultures were maintained on PDA slants and stored at 4°C in darkness. Colonies varied from light gray to olive green in color, produced abundant aerial hyphae, and had fluffy mycelial growth on PDA after 14 days. Both isolates were tentatively identified as Alternaria based on multicelled conidial morphology resembling “fragmentation grenades” that were medium brown in color, and obclavate to obpyriform catentulate with longitudinal and transverse septa attached in chains on simple conidiophores (2). Conidia ranged from 15 to 60 μm (mean 25.5 μm) long and 10 to 25 μm (mean 13.6 μm) wide (n = 50) with 1 to 6 transverse and 0 to 1 longitudinal septa per spore. To identify both isolates to the species level, genomic DNA was extracted from mycelial plugs and gene specific primers (ALT-HIS3F/R) were used via conventional PCR to amplify a portion of the histone gene (357 bp) (Jurick II, unpublished). Amplicons were sequenced using the Sanger method, and the forward and reverse sequences of each amplicon were assembled into a consensus representing 2× coverage. A megaBLAST analysis revealed that the isolates were 99% identical to Alternaria alternata sequences in GenBank (Accession No. AF404617), which was previously identified to cause decay on stored apple fruit in South Africa. To prove pathogenicity, Koch's postulates were conducted using organic ‘Gala’ apples. The fruit were surface disinfested with soap and water and sprayed with 70% ethanol to runoff. Wounds, 3 mm deep, were done using a sterile nail and 50 μl of a conidial suspension (1 × 104 conidia/ml) was introduced into each wound per fruit. Fruit were then stored at 25°C in 80 count boxes on paper trays for 21 days. Water only was used as a control. Ten fruit were inoculated with each isolate or water only (control) and the experiment was repeated once. Symptoms of decay observed on inoculated were ‘Gala’ apple fruit were identical to the symptoms initially observed on ‘Nittany’ apples obtained from cold storage after 21 days. No symptoms developed on fruit in the controls. A. alternata was re-isolated 100% from apple inoculated with the fungus, completing Koch's postulates. A. alternata has been documented as a pre- and postharvest pathogen on Malus spp. (3). To our knowledge, this is the first report of postharvest decay caused by A. alternata on apple fruit during cold storage in Pennsylvania. References: (1) A. L. Biggs et al. Plant Dis. 77:976, 1993. (2) E. G. Simmons. Alternaria: An Identification Manual. CBS Fungal Biodiversity Center, Utrecht, the Netherlands, 2007. (3) R. S. Spotts. Pages 56-57 in: Compendium of Apple and Pear Diseases, A. L. Jones and H. S. Aldwinkle, eds. American Phytopathological Society, St. Paul, MN, 1990.

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First Report of Alternaria tenuissima Causing Postharvest Decay on Apple Fruit from Cold Storage in the United States

Plant Disease ◽

10.1094/pdis-07-13-0802-pdn ◽

2014 ◽

Vol 98 (5) ◽

pp. 690-690 ◽

Cited By ~ 1

Author(s):

L. P. Kou ◽

V. L. Gaskins ◽

Y. G. Luo ◽

W. M. Jurick

Keyword(s):

United States ◽

South Africa ◽

Cold Storage ◽

Fungal Pathogens ◽

The United States ◽

Apple Fruit ◽

Conidial Suspension ◽

Single Spore ◽

Alternaria Tenuissima ◽

First Report

Apples are grown and stored for 9 to 12 months under controlled atmosphere conditions in the United States. During storage, apples are susceptible to various fungal pathogens, including several Alternaria species (2). Alternaria tenuissima (Nees) Wiltshire causes dry core rot (DCR) on apples during storage and has recently occurred in South Africa (1). Losses range widely, but typically occur at 6 to 8% annually due to this disease (2). In February 2013, ‘Nittany’ apples with round, dark-colored, dry, spongy lesions were obtained from wooden bins in a commercial cold storage facility located in Pennsylvania. Symptomatic fruits were transported to the lab, rinsed with sterile water, and the lesions were sprayed with 70% ethanol until runoff and wiped dry. The skin was aseptically removed with a scalpel, and asymptomatic tissue was placed onto potato dextrose agar (PDA) and incubated at 25°C. Two single-spore isolates were propagated on PDA and permanent cultures were maintained as slants and stored at 4°C. The fungus produced a cottony white mycelium that turned olive-green to brown with abundant aerial hyphae and had a dark brown to black reverse on PDA. Isolates were identified as Alternaria based on conidial morphology as the spores were slightly melanized and obclavate to obpyriform catentulate with longitudinal and transverse septa attached in unbranched chains on simple short conidiophores. Conidia ranged from 10 to 70 μm long (mean 27.7 μm) and 5 to 15 μm wide (mean 5.25 μm) (n = 50) with 1 to 6 transverse and 0 to 2 longitudinal septa. Conidial beaks, when present, were short (5 μm or less) and tapered. Mycelial genomic DNA was extracted, and a portion of the histone gene (357 bp) was amplified via gene specific primers (Alt-His3-F/R) using conventional PCR (Jurick II, unpublished). The forward and reverse sequences were assembled into a consensus representing 2× coverage and MegaBLAST analysis showed that both isolates were 100% identical to Alternaria tenuissima isolates including CR27 (GenBank Accession No. AF404622.1) that caused DCR on apple fruit during storage in South Africa. Koch's postulates were conducted using 10 organic ‘Gala’ apple fruit that were surface sterilized with soap and water, sprayed with 70% ethanol, and wiped dry. The fruit were aseptically wounded with a nail to a 3 mm depth, inoculated with 50 μl of a conidial suspension (1 × 104 conidia/ml), and stored at 25°C in 80 count boxes on paper trays for 21 days. Mean lesion diameters on inoculated ‘Gala’ apple fruit were 19.1 mm (±7.4), water only controls (n = 10 fruit) were symptomless, and the experiment was repeated. Symptoms observed on artificially inoculated ‘Gala’ apple fruit were similar to the decay observed on ‘Nittany’ apples from cold storage. Based on our findings, it is possible that A. tenuissima can cause decay that originates from wounded tissue in addition to dry core rot, which has been reported (1). Since A. tenuissima produces potent mycotoxins, even low levels of the pathogen could pose a health problem for contaminated fruit destined for processing and may impact export to other countries. To the best of our knowledge, this is the first report of alternaria rot caused by A. tenuissima on apple fruit from cold storage in the United States. References: (1) J. C. Combrink et al. Decid. Fruit Grow. 34:88, 1984. (2) M. Serdani et al. Mycol. Res. 106:562, 2002. (3) E. E. Stinson et al. J. Agric. Food Chem. 28:960, 1980.

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First Report of Colletotrichum fioriniae Causing Postharvest Decay on ‘Nittany’ Apple Fruit in the United States

Plant Disease ◽

10.1094/pdis-08-13-0816-pdn ◽

2014 ◽

Vol 98 (7) ◽

pp. 993-993 ◽

Cited By ~ 14

Author(s):

L. P. Kou ◽

V. Gaskins ◽

Y. G. Luo ◽

W. M. Jurick

Keyword(s):

United States ◽

Cold Storage ◽

Management Practices ◽

The United States ◽

Apple Fruit ◽

Morphological Identification ◽

Conidial Suspension ◽

First Report ◽

Postharvest Decay ◽

Bitter Rot

Bitter rot of apple is caused by Colletotrichum acutatum and C. gleosporioides and is an economically important disease in the mid-Atlantic and southern regions of the United States (1). However, other Colletotrichum spp. have been found to infect apple and pear fruit in Croatia that include C. fioriniae and C. clavatum (3). The disease is favorable under wet, humid conditions and can occur in the field or during storage causing postharvest decay (2). In February 2013, ‘Nittany’ apples with round, brown, dry, firm lesions having acervuli in concentric rings were observed at a commercial cold storage facility in Pennsylvania. Samples were placed on a paper tray in an 80-count apple box and immediately transported to the lab. Fruit were rinsed with sterile water, and lesions were sprayed with 70% ethanol until runoff. The skin was aseptically removed with a scalpel, and tissue under the lesion was placed onto potato dextrose agar (PDA) petri dishes. Dishes were incubated at 25°C with constant light, and a single-spore isolate was propagated on PDA. Permanent cultures were maintained as PDA slants stored at 4°C in darkness. The isolate was identified as a Colletotrichum sp. based on culture morphology, having light gray mycelium with a pinkish reverse and abundant pin-shaped melanized acervuli oozing pink conidia on PDA. Conidia were fusiform, pointed at one or both ends, one-celled, thin-walled, aseptate, hyaline, and averaged 10.5 μm (7.5 to 20 μm) long and 5.1 μm (5 to 10 μm) wide (n = 50). Genomic DNA was extracted from mycelia and amplified using conventional PCR and gene specific primers for 313 bp of the Histone 3 gene and with ITS4/5 primers for the internal transcribed spacer (ITS) rDNA region. MegaBLAST analysis of both gene sequences showed that our isolate was identical to other Colletotrichum fioriniae sequences in GenBank and was 100% identical to culture-collection C. fioriniae isolate CBS:128517, thus confirming the morphological identification. To prove pathogenicity, Koch's postulates were conducted using organic ‘Gala’ apple fruit that were washed with soap and water, sprayed with 70% ethanol, and wiped dry. The fruit were wounded with a sterile nail to a 3-mm depth, inoculated with 50 μl of a conidial suspension (1 × 104 conidia/ml), and stored at 25°C in 80-count boxes on paper trays for 14 days. Lesion diameter was measured from 10 replicate fruit with a digital micrometer and averaged 31.2 mm (±2.5 mm) over two experiments (n = 20). Water-only controls were symptomless. Artificially inoculated ‘Gala’ apples had identical external and internal symptoms (v-shaped decay pattern when the fruit were cut in half) to those observed on ‘Nittany’ apples that were originally obtained from cold storage. Bitter rot caused by C. fioriniae may become an emerging problem for the pome fruit growing industry in the near future, and may require investigation of new disease management practices to control this fungus. This is the first report of postharvest decay caused by C. fioriniae on apple fruit from cold storage in the United States. References: (1) H. W. Anderson. Diseases of Fruit Crops. McGraw-Hill, New York, 1956. (2) A. R. Biggs et al. Plant Dis. 85:657, 2001. (3) D. Ivic et al. J. Phytopathol. 161:284, 2013.

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First Report of Anthracnose on Hymenocallis littoralis Caused by Colletotrichum siamense in China

Plant Disease ◽

10.1094/pdis-02-21-0405-pdn ◽

2021 ◽

Author(s):

Yong Huang ◽

Yue Qin zhang ◽

Han Hu ◽

Nai Feng

Keyword(s):

Its Region ◽

Leaf Spot Disease ◽

Data Sets ◽

Conidial Suspension ◽

Single Spore ◽

Koch’S Postulates ◽

First Report ◽

Medicinal Value ◽

Sterile Needle ◽

Koch's Postulates

Spider lily (Hymenocallis littoralis (Jacq.) Salisb.) is a widely cultivated horticultural plant worldwide and has ornamental and medicinal value. Spider lily plants were seriously affected by a leaf spot disease in the campus of Guangdong Ocean University and gardens in Zhanjiang city in February 2018 with an incidence of 30 to 100%. Affected leaves usually developed small circular purple spots, which enlarged to oval spots and large irregular spots. The spots were brown at the center, deep purple at the border and surrounded by a yellow halo. Diseased cultivars were collected in Zhanjiang city, Gangzhou city in Guangdong province and and Zhangping city in Fujian province. Symptomatic leaf samples were disinfested with 1% NaOCl, and cultured on sucrose agar (PSA) at 28 °C for one week. Ten single-spore isolates were recovered from PSA medium. Colonies developing on PSA were grayish white with a regular border. Conidia were straight, hyaline with rounded ends, 4.3 to 6.1×12.8 to 32.1μm (n = 50 conidia of each isolate). Fungal mycelia were hyaline, septate, and branched. Conidia were born on a long conidiogenous cell, appressoria were oval, 6.7 to 10.7 × 5.2 to 6.2 μm (n=50). The isolates were morphologically identified as Colletotrichum sp. (Weir et al. 2012). Tests of pathogenicity were performed according to Koch's postulates using three isolates. Fresh wounds were made with a sterile needle on the healthy surface of leaves of H. littoralis at the 4- to 6-leaf stage and each leaf was covered with a piece of cotton drenched with 200 μL of conidial suspension (106 conidia/ml) from each isolate. Control seedlings were inoculated identically except sterile water was used to drench the cotton. Inoculated plants were placed in a moisturizing light incubator at 25℃ and 80% humidity under a 12-h light/dark cycle for 20 days and examined daily to monitor disease symptom development. Small round brown spots were observed at the inoculation sites 3 days after the inoculation. The brown spots developed into large brown lesions 5 days after inoculation. There were no symptoms observed in the water-inoculated plants. A Colletotrichum spp. strain based on morphology was consistently reisolated from leaves lesions fulfilling Koch’s postulates. For molecular identification, the internal transcribed spacer (ITS) region of ribosomal DNA, calmodulin (CAL), Tublin (Tub) and Apmat loci of three isolates were amplified using primer pairs of ITS4/ITS5, CL1C/CL2C, T1/T2 and AM-F/AM-R (Sharma et al. 2015). A phylogenetic tree derived from a neighbor-joining analysis of a concatenated alignment of ITS, CAL, Tub and ApMAT sequences was created. The accession numbers of three isolates GZHLCG, ZJHLCG and FJHLCG used in this study were MW553083, MN540457, MN540458 for ITS, MW553087- MW553089 for CL, MW553090-MW553092 for Tub and MW553084-MW553086 for ApMAT. The sequences of the three isolates were aligned with related species of Colletotrichum (Sharma et al. 2015). Analyses based on concatenated data sets of four genes showed that the sequences had high levels of identity to those of the C. siamense strains. According to both morphological and sequence analyses, the H. littoralis pathogen was identified as C. siamense. There is a report of foliar diseases on H. littoralis caused by Colletotrichum sp. (Tan et al., 2009). To our knowledge, this is the first report of anthracnose on H. littoralis caused by C. siamense in China. Identification of the pathogen provide valuable information for diagnosis and controlling this disease in H. littoralis.

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First Report of Fusarium avenaceum Causing Postharvest Decay of ‘Gala’ Apple Fruit in the United States

Plant Disease ◽

10.1094/pdis-07-13-0803-pdn ◽

2014 ◽

Vol 98 (5) ◽

pp. 690-690

Author(s):

L. P. Kou ◽

V. L. Gaskins ◽

Y. G. Luo ◽

W. M. Jurick

Keyword(s):

United States ◽

Cold Storage ◽

The United States ◽

Apple Fruit ◽

Fusarium Avenaceum ◽

Primary Concern ◽

Processing Industry ◽

First Report ◽

Postharvest Decay ◽

Fusarium Rot

Apples are kept in controlled atmosphere cold storage for 9 to 12 months and are highly susceptible to postharvest decay caused by various fungi. Fusarium avenaceum is a wound pathogen that has been shown to account for the majority of Fusarium rot on apple fruit in Croatia (1). F. avenaceum produces an array of mycotoxins including moniliformin, acuminatopyrone, and chrysogine, which are of primary concern for the apple processing industry (2). In February 2013, ‘Gala’ apple fruits with soft, circular, brown, watery lesions with characteristic abundant whitish mycelium covering the surface of the colonized fruit were obtained from bins from a commercial storage facility located in Pennsylvania. Several samples were collected and prepared for pathogen isolation. Apples were rinsed with sterile water, and the lesions were sprayed with 70% ethanol until runoff. The apple skin was aseptically removed with a scalpel, and asymptomatic tissue was placed onto full strength potato dextrose agar (PDA) petri plates without antibiotics and incubated at 25°C under natural light. Two single-spore isolates were propagated on PDA and permanent cultures were maintained as slants and stored in a cold room at 4°C in the dark. Fungal colonies initially formed abundant fluffy white mycelium and produced a golden orange pigment on PDA at 25°C. Isolates were identified as Fusarium based on cultural and conidial morphology as macroconidia were slightly falcate, thin-walled, usually 3 to 5 septate, with a tapering apical cell that was on average 23.6 μm long × 5.0 μm wide (n = 50). Microconidia were produced on PDA plates while chlamydospores were not evident. Identity of the isolates was confirmed through DNA extraction followed by amplification and sequencing of the translation elongation factor (EF-1α, 350 bp) gene region. The amplicons were sequenced using the forward and reverse primers and assembled into a consensus representing 2X coverage. MegaBLAST analysis revealed that both isolates were 100% identical with many other culture collection F. avenaceum sequences in Genbank (Accessions JQ949291.1, JQ949305.1, and JQ949283.1), which confirms their identification in conjunction with the morphological observations. Koch's postulates were conducted to determine pathogenicity using organic ‘Gala’ apple fruit that were surface sanitized with soap and water, sprayed with 70% ethanol, and wiped dry. The fruit were wounded with a finishing nail to 3 mm depth, inoculated with 50 μl of a conidial suspension (1 × 104 conidia/ml) using a hemocytometer, and stored at 25°C in 80-count boxes on paper trays for 21 days. Water-only controls were symptomless. Ten fruit composed a replicate for each isolate, and the experiment was repeated. Symptoms observed on artificially inoculated ‘Gala’ apple fruit were identical to the decay observed on ‘Gala’ apples that were obtained from cold storage. Decay caused by F. avenaceum may represent an emerging problem for the apple storage and processing industry. Therefore, it is important to monitor for this pathogen to prevent future losses and mycotoxin contamination of processed fruit products caused by this fungus. To the best of our knowledge, this is the first report of Fusarium rot caused by F. avenaceum on apple fruit from cold storage in the United States. References: (1) Z. Sever et al. Arch. Ind. Hygiene Toxicol. 63:463, 2012. (2) J. L. Sorenson. J. Agric. Food Chem. 57:1632, 2009.

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First Report of Penicillium crustosum Causing Blue Mold on Stored Apple Fruit in Serbia

Plant Disease ◽

10.1094/pdis-02-14-0179-pdn ◽

2014 ◽

Vol 98 (10) ◽

pp. 1430-1430 ◽

Cited By ~ 5

Author(s):

I. Vico ◽

V. Gaskins ◽

N. Duduk ◽

Miljan Vasić ◽

J. J. Yu ◽

...

Keyword(s):

Apple Fruit ◽

Conidial Suspension ◽

Blue Mold ◽

Koch’S Postulates ◽

First Report ◽

Control Fruit ◽

Wide Range ◽

Penicillium Crustosum ◽

Golden Delicious ◽

Koch's Postulates

Penicillium crustosum Thom (1930) causes blue mold on pome fruits and is also regularly found on cheese, nuts, and soil (1,3). The fungus produces a wide range of mycotoxins such as penitrem A, roquefortine C, terrestric acid, and cyclopenol, which impact human health (1). In January and February 2013, 20 decayed apples, ‘Golden Delicious’ and ‘Jonagold’ (Malus × domestica Borkh.) with blue mold symptoms were collected from cold storages in Svilajnac and Bela Crkva, Serbia. Decayed areas were light to medium brown with blue green sporulation on the surface of the lesion. Decayed tissue was soft and watery with a sharp margin between the diseased and healthy areas. One isolate from each cultivar was designated JP2 (‘Golden Delicious’) and JBC7 (‘Jonagold’) and further characterized. Conidiophores of both isolates were terverticillate, stipes were septate with rough walls, and phialides were ampulliform. Conidia were smooth, borne in columns, and were spherical to subglobose. Conidial dimensions for JP2 were 3.2 to 4.56 (3.73) × 2.64 to 4.3 (3.32) μm and for JBC7 were 3.1 to 4.46 (3.65) × 2.81 to 4.27 (3.31) μm (n = 50). The isolates were cultured on Czapek yeast autolysate agar (CYA), malt extract agar (MEA), and yeast extract sucrose agar (YES) media and incubated at 25°C for 7 days. Mycelia were white with heavy sporulation yielding grayish green colonies on all media. Colonies were radially sulcate and velutinous, with clear exudate, and produced a yellow to orange reverse on CYA and YES. On MEA, colonies were plane, low, and mycelia subsurface with conidia having a dry powdery appearance. Crusts of conidial masses formed after 10 or more days. No growth was observed on CYA when these isolates were incubated at 37°C. Both isolates were identified as P. crustosum Thom using morphological characters according to (2) and (1). Species level identification was confirmed by isolating genomic DNA followed by amplification of the β-tubulin locus using gene specific primers via conventional PCR (4). MegaBLAST analysis of the 2X consensus nucleotide sequences revealed that JP2 and JBC7 (GenBank KJ433984 and 85) were 99% identical to P. crustosum culture collection isolate IBT 21518 (JN112030.1). Koch's postulates were examined using two apple cvs. Idared and Kolacara. Ten fruit per cultivar per isolate were inoculated on two sides of each fruit; 20 fruit were used as water-only inoculated controls. Fruit were washed with soap and water, surface sanitized with 70% ethanol, and placed into polyethylene boxes. Using a finishing nail, 4-mm wounds were created and inoculated with 50 μl of a 3 × 105/ml conidial suspension or Tween-treated sterile distilled water. Boxes with inoculated and control fruit were stored at 25°C for 10 days. The inoculated fruit developed small, soft, watery lesions, which enlarged into decayed areas with defined edges and abundant sporulation on the surface. Symptoms were identical to the original ones, while the control fruit remained symptomless. The fungus was re-isolated from infected tissue and showed the same morphological characteristics as the original isolates, thus completing Koch's postulates. Blue mold occurs during long term storage of apples and is predominantly caused by P. expansum. This is the first report of P. crustosum causing postharvest blue mold decay on apple fruit obtained from storage in Serbia and indicates that P. crustosum is an emerging pathogen for the Serbian pome fruit growing and packing industry. References: (1) J. C. Frisvad and R. A. Samson. Stud. Mycol. 49:1, 2004. (2) J. I. Pitt and A. D. Hocking. Fungi and Food Spoilage, 239. Springer, 2009. (3) P. G. Sanderson and R. A. Spotts. Phytopathology 85:103. 1995. (4) P. L. Sholberg et al. Postharvest Biol. Technol. 36:41, 2005.

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First Report of Pathogenicity of Fusarium sporotrichioides and Fusarium acuminatum on Sunflowers in the United States

Plant Health Progress ◽

10.1094/php-2010-0915-02-br ◽

2010 ◽

Vol 11 (1) ◽

pp. 42 ◽

Cited By ~ 4

Author(s):

F. Mathew ◽

B. Kirkeide ◽

T. Gulya ◽

S. Markell

Keyword(s):

United States ◽

Helianthus Annuus ◽

The United States ◽

Fusarium Sporotrichioides ◽

Charcoal Rot ◽

Koch’S Postulates ◽

First Report ◽

Fusarium Acuminatum ◽

Helianthus Annuus L ◽

Koch's Postulates

Widespread infection of charcoal rot was observed in a commercial sunflower field in Minnesota in September 2009. Based on morphology, isolates were identified as F. sporotrichioides and F. acuminatum. Koch's postulates demonstrated pathogencity of both species. To our knowledge, this is the first report of F. sporotrichoides and F. acuminatum causing disease on Helianthus annuus L. in the United States. Accepted for publication 23 August 2010. Published 15 September 2010.

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First Report of Alternaria Leaf Spot of Banana Caused by Alternaria alternata in the United States

Plant Disease ◽

10.1094/pdis-01-13-0007-pdn ◽

2013 ◽

Vol 97 (8) ◽

pp. 1116-1116 ◽

Cited By ~ 3

Author(s):

V. Parkunan ◽

S. Li ◽

E. G. Fonsah ◽

P. Ji

Keyword(s):

United States ◽

Alternaria Alternata ◽

Leaf Spot ◽

Morphological Characteristics ◽

The United States ◽

Its Sequencing ◽

Single Spore ◽

First Report ◽

Alternaria Leaf Spot ◽

Leaf Spots

Research efforts were initiated in 2003 to identify and introduce banana (Musa spp.) cultivars suitable for production in Georgia (1). Selected cultivars have been evaluated since 2009 in Tifton Banana Garden, Tifton, GA, comprising of cold hardy, short cycle, and ornamental types. In spring and summer of 2012, 7 out of 13 cultivars (African Red, Blue Torres Island, Cacambou, Chinese Cavendish, Novaria, Raja Puri, and Veinte Cohol) showed tiny, oval (0.5 to 1.0 mm long and 0.3 to 0.9 mm wide), light to dark brown spots on the adaxial surface of the leaves. Spots were more concentrated along the midrib than the rest of the leaf and occurred on all except the newly emerged leaves. Leaf spots did not expand much in size, but the numbers approximately doubled during the season. Disease incidences on the seven cultivars ranged from 10 to 63% (10% on Blue Torres Island and 63% on Novaria), with an average of 35% when a total of 52 plants were evaluated. Six cultivars including Belle, Ice Cream, Dwarf Namwah, Kandarian, Praying Hands, and Saba did not show any spots. Tissue from infected leaves of the seven cultivars were surface sterilized with 0.5% NaOCl, plated onto potato dextrose agar (PDA) media and incubated at 25°C in the dark for 5 days. The plates were then incubated at room temperature (23 ± 2°C) under a 12-hour photoperiod for 3 days. Grayish black colonies developed from all the samples, which were further identified as Alternaria spp. based on the dark, brown, obclavate to obpyriform catenulate conidia with longitudinal and transverse septa tapering to a prominent beak attached in chains on a simple and short conidiophore (2). Conidia were 23 to 73 μm long and 15 to 35 μm wide, with a beak length of 5 to 10 μm, and had 3 to 6 transverse and 0 to 5 longitudinal septa. Single spore cultures of four isolates from four different cultivars were obtained and genomic DNA was extracted and the internal transcribed spacer (ITS1-5.8S-ITS2) regions of rDNA (562 bp) were amplified and sequenced with primers ITS1 and ITS4. MegaBLAST analysis of the four sequences showed that they were 100% identical to two Alternaria alternata isolates (GQ916545 and GQ169766). ITS sequence of a representative isolate VCT1FT1 from cv. Veinte Cohol was submitted to GenBank (JX985742). Pathogenicity assay was conducted using 1-month-old banana plants (cv. Veinte Cohol) grown in pots under greenhouse conditions (25 to 27°C). Three plants were spray inoculated with the isolate VCT1FT1 (100 ml suspension per plant containing 105 spores per ml) and incubated under 100% humidity for 2 days and then kept in the greenhouse. Three plants sprayed with water were used as a control. Leaf spots identical to those observed in the field were developed in a week on the inoculated plants but not on the non-inoculated control. The fungus was reisolated from the inoculated plants and the identity was confirmed by morphological characteristics and ITS sequencing. To our knowledge, this is the first report of Alternaria leaf spot caused by A. alternata on banana in the United States. Occurrence of the disease on some banana cultivars in Georgia provides useful information to potential producers, and the cultivars that were observed to be resistant to the disease may be more suitable for production. References: (1) E. G. Fonsah et al. J. Food Distrib. Res. 37:2, 2006. (2) E. G. Simmons. Alternaria: An identification manual. CBS Fungal Biodiversity Center, Utrecht, Netherlands, 2007.

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First Report of Phytophthora syringae Causing Rot on Apples in Cold Storage in the United States

Plant Disease ◽

10.1094/pdis.2002.86.6.693b ◽

2002 ◽

Vol 86 (6) ◽

pp. 693-693 ◽

Cited By ~ 2

Author(s):

R. A. Spotts ◽

G. G. Grove

Keyword(s):

United States ◽

Cold Storage ◽

The United States ◽

River Valley ◽

Fruit Rot ◽

Commonwealth Mycological Institute ◽

Postharvest Diseases ◽

First Report ◽

Postharvest Decay ◽

Wide Range

A decay of ‘Granny Smith’ apples (Malus domestica Borkh.) was observed in 1988, 1990, and 1991 on fruit grown in the lower Hood River Valley of Oregon and stored at 0°C. Harvested fruit were drenched with thiabendazole and stored in October in all years. In mid-November, fruit were sized, drenched with sodium hypochlorite, and returned to cold storage. Decay was observed in January when fruit were removed from cold storage, sorted, and packed. Decayed areas were light brown and firm with a slightly indefinite margin. Losses were less than 1% of fruit packed. Diseased fruit were surface-disinfested with 95% ethanol, and tissue pieces were transferred aseptically to potato dextrose agar acidified with lactic acid and incubated at approximately 22°C. The fungus consistently isolated was identified as Phytophthora syringae (Kleb.) Kleb. based on morphological characters (3). Sporangia were persistent and averaged 60 μm long (range 59 to 69) × 40 μm wide (range 37 to 43). Antheridia were paragynous, and oospores averaged 37 μm (range 31 to 46). ‘Golden Delicious’, ‘Granny Smith’, and ‘Gala’ apples were inoculated with mycelial plugs from a 7-day-old culture of P. syringae and incubated 12 days at 5°C and 7 to 12 days at 22°C. Twenty fruit of each cultivar were used—ten were inoculated, and ten uninoculated fruit served as controls. Lesions developed on all inoculated fruit but not on uninoculated controls. Lesions were spherical, chocolate brown, and firm with no evidence of external mycelia. Lesion morphology was similar on all cultivars. P. syringae was reisolated from lesion margins of all infected fruit. This postharvest decay of apples has not been observed in the Hood River Valley since 1991. Fruit rot of apples caused by P. syringae is known in Canada (1) and is common in the United Kingdom (2), but has not been reported previously in the United States. To our knowledge, this is the first report of postharvest decay of apples by P. syringae in the United States. References: (1) R. G. Ross and C. O. Gourley. Can. Plant Dis. Surv. 49:33, 1969. (2) A. L. Snowdon. A Color Atlas of Postharvest Diseases. CRC Press, Inc., Boca Raton, FL, 1990. (3) G. M. Waterhouse. The Genus Phytophthora. Misc. Publ. 12. The Commonwealth Mycological Institute, Kew, Surrey, England, 1956.

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First Report of Passalora Leaf Spot Caused by Passalora bougainvilleae on Bougainvillea in Mexico

Plant Disease ◽

10.1094/pdis-11-10-0787 ◽

2011 ◽

Vol 95 (6) ◽

pp. 775-775 ◽

Cited By ~ 1

Author(s):

V. Ayala-Escobar ◽

V. Santiago-Santiago ◽

A. Madariaga-Navarrete ◽

A. Castañeda-Vildozola ◽

C. Nava-Diaz

Keyword(s):

Uv Light ◽

Disease Incidence ◽

Morphological Characteristics ◽

The United States ◽

Pathogenicity Test ◽

Commonwealth Mycological Institute ◽

Conidial Suspension ◽

Single Spore ◽

First Report ◽

Bougainvillea Spectabilis

Bougainvillea (Bougainvillea spectabilis Willd) growing in 28 gardens during 2009 showed 100% disease incidence and 3 to 7% disease severity. Bougainvilleas with white flowers were the most affected. Symptoms consisted of light brown spots with dark brown margins visible on adaxial and abaxial sides of the leaves. Spots were circular, 2 to 7 mm in diameter, often surrounded by a chlorotic halo, and delimited by major leaf veins. Single-spore cultures were incubated at 24°C under near UV light for 7 days to obtain conidia. Pathogenicity was confirmed by spraying a conidial suspension (1 × 104 spores/ml) on leaves of potted bougainvillea plants (white, red, yellow, and purple flowers), incubating the plants in a dew chamber for 48 h and maintaining them in a greenhouse (20 to 24°C). Identical symptoms to those observed at the residential gardens appeared on inoculated plants after 45 to 60 days. The fungus was reisolated from inoculated plants that showed typical symptoms. No symptoms developed on control plants treated with sterile distilled water. The fungus produced distinct stromata that were dark brown, spherical to irregular, and 20 to 24 μm in diameter. Conidiophores were simple, born from the stromata, loose to dense fascicles, brown, straight to curved, not branched, zero to two septate, 14 × 2 μm, with two to four conspicuous and darkened scars. The conidia formed singly, were brown, broad, ellipsoid, obclavate, straight to curved with three to four septa, 40 × 4 μm, and finely verrucous with thick hilum at the end. Fungal DNA from the single-spore cultures was obtained using a commercial DNA Extraction Kit (Qiagen, Valencia, CA); ribosomal DNA was amplified with ITS5 and ITS4 primers and sequenced. The sequence was deposited at the National Center for Biotechnology Information Database (GenBank Accession Nos. HQ231216 and HQ231217). The symptoms (4), morphological characteristics (1,2,4), and pathogenicity test confirm the identity of the fungus as Passalora bougainvilleae (Muntañola) Castañeda & Braun (= Cercosporidium bougainvilleae Muntañola). This pathogen has been reported from Argentina, Brazil, Brunei, China, Cuba, El Salvador, India, Indonesia, Jamaica, Japan, Thailand, the United States, and Venezuela (3). To our knowledge, this is the first report of this disease on B. spectabilis Willd in Mexico. P. bougainvilleae may become an important disease of bougainvillea plants in tropical and subtropical areas of Mexico. References: (1) U. Braun and R. R. Castañeda. Cryptogam. Bot. 2/3:289, 1991. (2) M. B. Ellis. More Dematiaceous Hypomycetes. Commonwealth Mycological Institute, Kew, Surrey, UK, 1976. (3) C. Nakashima et al. Fungal Divers. 26:257, 2007. (4) K. L. Nechet and B. A. Halfeld-Vieira. Acta Amazonica 38:585, 2008.

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Recent Outbreak of Soybean Sudden Death Syndrome Caused by Fusarium virguliforme and F. tucumaniae in Argentina

Plant Disease ◽

10.1094/pdis.2004.88.9.1044c ◽

2004 ◽

Vol 88 (9) ◽

pp. 1044-1044 ◽

Cited By ~ 6

Author(s):

M. Scandiani ◽

D. Ruberti ◽

K. O'Donnell ◽

T. Aoki ◽

R. Pioli ◽

...

Keyword(s):

United States ◽

Phylogenetic Analyses ◽

The United States ◽

Positive Control ◽

Koch’S Postulates ◽

First Report ◽

Molecular Phylogenetic ◽

Soil Infestation ◽

Pathogenicity Tests ◽

Koch's Postulates

Sudden death syndrome (SDS) of soybean was detected initially in Argentina during 1991-1992 in the Pampas Region and 1992-1993 in the Northwest Region. The first report of the fulfillment of Koch's postulates of SDS caused by Fusarium solani f. sp. glycines in Argentina was published in 2003 (3). Subsequently, analyses have shown that F. solani f. sp. glycines represents several morphologically and phylogenetically distinct species, including F. tucumaniae in Argentina and F. virguliforme in the United States (1). Isolations were made from plants that exhibited typical SDS symptoms (interveinal foliar chlorosis and necrosis leading to defoliation of the leaflets but not the petioles) from fields in Santa Fe and Buenos Aires provinces in 2001, 2002, and 2003. To determine which species are responsible for SDS in Argentina, cultures of eight slow growing isolates that developed bluish pigmentation and produced abundant macroconidia in sporodochia on potato dextrose agar were subjected to morphological and molecular phylogenetic analyses and pathogenicity tests. Morphological analyses demonstrated that three of the isolates were F. virguliforme and five were F. tucumaniae. Isolates of F. tucumaniae produced long and narrow sporodochial conidia while F. virguliforme produced diagnostic comma-shaped conidia. Molecular phylogenetic analyses of DNA sequences from multiple loci confirmed morphology-based identifications and showed that the soybean SDS pathogen in the United States, F. virguliforme, was also present in Argentina. To our knowledge, this is the first report of F. virguliforme in Argentina and of this pathogen outside the United States. Five isolates of F. tucumaniae and three isolates of F. virguliforme were used for pathogenicity tests. F. virguliforme isolate 171 provided by J. Rupe (University of Arkansas, Fayetteville) was used as a positive control. Soybean cultivars Ripley, RA 702, Pioneer 9492RR, Spencer, and A-6445RG were inoculated with each of the isolates tested in a greenhouse assay using soil infestation and toothpick methods (2). All eight isolates produced typical foliar SDS symptoms 15 to 25 days after inoculation. Severity of foliar symptoms averaged 3.3 for F. virguliforme, 2.6 for F. tucumaniae, and 3.3 for the positive control using a disease severity scale in which 1 = no symptoms and 5 = severely infected or dead plants. Under these conditions, F. virguliforme appeared to be more virulent than F tucumaniae. Noninoculated plants remained symptomless. Koch's postulates were confirmed with soybean cultivars RA 702 and A6445RG. Isolates recovered from symptomatic plants inoculated by the soil infestation and toothpick methods were identical to those used to inoculate the plant. Strains were recovered at frequencies of 100 and 60% from plants inoculated by the toothpick and soil infestation methods, respectively. To our knowledge, this is the first report of the fulfillment of Koch's postulates for F. tucumaniae and F. virguliforme in Argentina. References: (1) T. Aoki et al. Mycologia 95:660, 2003. (2) K. W. Roy et al. Plant Dis. 81:1100, 1997 (3) M. Scandiani et al. Plant Dis. 87:447, 2003.

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