First Report of Colletotrichum phormii Causing Anthracnose on New Zealand Flax in the United States

Phormium colensoi Hook.f. (syn. P. cookianum), New Zealand flax, (family Xanthorrhoeaceae) is popular in ornamental landscapes in the United States because of its sturdy blade-like foliage available in diverse colors. In February 2012, the Oregon State University Plant Clinic received three potted plants of P. colensoi ‘Black Adder’ from a commercial nursery in Santa Cruz County, California. The margins and midribs of several leaves had brown lesions that were variable in size, and fusiform to ellipsoidal in shape. Embedded in the lesions were black acervuli without setae that exuded salmon-colored spore masses under moist conditions. Conidia were hyaline, cylindrical to fusiform, straight to slightly curved, and 22.4 to 35.2 × 4.0 to 6.4 (average 24.7 × 4.9) μm. Based on morphology, the fungus was confirmed by USDA-APHIS National Identification Services to be Colletotrichum phormii (Henn.) D.F. Farr & Rossman (2). In March 2012, the California Department of Food and Agriculture Plant Pest Diagnostic Lab received additional samples from the same nursery lot (25% disease incidence) from which a similar fungus was recovered. rDNA sequences of the internal transcribed spacer (ITS) region from the California isolate (GenBank KC122681), amplified using primers ITS1 and ITS4 (2), were 100% identical to multiple species of Colletotrichum, including C. phormii by a BLAST query (JQ948446 through JQ948453). ITS sequence similarity alone is not sufficient to address Colletotrichum taxonomy and must be used in combination with host range and morphology (1). Pathogenicity of C. phormii (isolate CDFA986) was tested on three ‘Black Adder’ plants, which were inoculated with 6-mm agar plugs from a 14-day-old culture grown on half strength potato dextrose agar (PDA). Leaves were wound-inoculated along the midrib using colonized plugs (4). Five leaves per plant were inoculated with C. phormii plugs and five leaves per plant were treated with uncolonized PDA agar plugs as controls. Plants were sprayed with water and incubated in plastic bags at 22°C with a 12-h photoperiod. After 48 h, the bags and caps were removed and plants were kept under the same conditions. Two weeks later, water-soaked lesions had developed on the inoculated leaves. Lesions expanded along the midrib and became fusiform in shape after 21 to 28 days. C. phormii was isolated from lesion margins of all the inoculated leaves, but not from control leaves. This experiment was repeated once with similar results. Another Colletotrichum species, C. gloeosporiodes, also occurs on Phormium spp., but differs from C. phormii in morphology and symptom expression. Subsequent nursery and landscape surveys showed that anthracnose caused by C. phormii occurs on several P. colensoi cultivars as well as on P. tenax in five California counties including Santa Cruz, Yolo, Sacramento, San Luis Obispo, and Solano. C. phormii is also reported to infect P. colensoi and P. tenax in New Zealand, Europe, the United Kingdom, Australia, and South Africa (2,3). To our knowledge, this is the first report of C. phormii causing anthracnose on Phormium in North America. This disease could impact the American nursery trade and New Zealand flax production due to crop loss and increased production costs for pest management. References: (1) J. Crouch et al. Mycologia 101:648, 2009. (2) D. F. Farr et al. Mycol. Res. 110:1395, 2006. (3). H. Golzar and C. Wang. Australas. Plant Pathol. 5:110, 2010. (4) L. E. Yakabe et al. Plant Dis. 93:883, 2009.

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First Report of Black Rot of Carrots Caused by Alternaria radicina in Michigan

Plant Disease ◽

10.1094/pd-90-0684b ◽

2006 ◽

Vol 90 (5) ◽

pp. 684-684

Author(s):

C. Saude ◽

M. K. Hausbeck

Keyword(s):

United States ◽

New York ◽

Sequence Similarity ◽

Morphological Characteristics ◽

Its Region ◽

The United States ◽

Distilled Water ◽

First Report ◽

Plastic Bags ◽

Alternaria Sp

In April 2005, an Alternaria sp. was isolated from carrot (Daucus carota) roots harvested in the fall of 2004 and held at 1 to 3°C in a storage facility in Newaygo County, MI. The pathogen was readily isolated on water agar from root tissue exhibiting grayish black, sunken lesions. Morphological characteristics were noted 5 to 7 days after single-conidium cultures were established on potato dextrose agar (3). Sixteen Alternaria sp. isolates were recovered. Cultures were dark olive brown, and conidia were pigmented, ellipsoidal, and produced singly or in chains of two. Conidia were 35 to 45 μm long and 15 to18 μm in diameter, usually with three to eight transverse and one to four longitudinal septa. Pathogenicity of isolates was tested on carrot roots in the laboratory and carrot seedlings (cv. Goliath) in the greenhouse. In the laboratory, four surface-sterilized, whole carrot roots were sprayed until runoff with 2 × 106 conidia/ml of each isolate and incubated at 23 to 25°C in a moist chamber for 10 days. Controls were sprayed with sterile distilled water. Ten to fifteen days after inoculation, inoculated carrots exhibited grayish black, sunken lesions, and an Alternaria sp. was reisolated from the margin of the lesions. Controls remained healthy. In the greenhouse, seven pots containing one 2-week-old carrot seedling were watered to saturation and plants were sprayed until runoff with 2 × 106 conidia/ml for each isolate. Control plants were sprayed with sterile distilled water. After inoculation, plants were enclosed in clear plastic bags, placed under 63% woven shade cloth and watered regularly. Black lesions were observed on the foliage 7 days after inoculation, and wilt and death of plants were observed 15 to 30 days after inoculation. Alternaria sp. was reisolated from the foliage of symptomatic plants. Control plants remained healthy. DNA was extracted from all isolates, and the nuclear ribosomal internal transcribed spacer (ITS) region amplified with primers ITS4 and ITS5 and sequenced. A portion of the ITS sequence has been deposited in the NCBI database (GenBank Accession No. DQ394073). A BLAST search of the NCBI database with the ITS sequences revealed A. radicina, Accession No AY154704, as the closest match with 100% sequence similarity. In September 2005, an Alternaria sp. was isolated from black lesions on carrot roots, crowns, and foliage that were collected from fields in Newaygo and Oceana counties, MI. The recovered isolates were morphologically similar to A. radicina isolates obtained from stored carrots in April 2005. First isolated and identified on stored carrots in New York (3), A. radicina is also present in other carrot-producing areas of the United States (1) and was isolated not only from stored carrots but also from carrots in the field (2) and carrot seeds (4). To our knowledge, this is the first report of A. radicina on stored and field carrots in Michigan, which signifies a serious risk to a carrot industry that ranks among the top five in the United States. References: (1) D. F. Farr et al. Fungi on Plants and Plant Produce in the United States.The American Phytopathological Society, St. Paul, MN, 1989. (2) R. G. Grogan and W. C. Snyder. Phytopathology 42:215, 1952. (3) F. C. Meier and E. D. Eddy. Phytopathology 12:157, 1922. (4) B. M. Pryor and R. L. Gilbertson. Plant Dis. 85:18, 2001.

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First Report of Stem and Foliage Blight of Chrysanthemum Caused by Phytophthora drechsleri in the United States

Plant Disease ◽

10.1094/pdis-03-21-0631-pdn ◽

2021 ◽

Author(s):

Charles Krasnow ◽

Nancy Rechcigl ◽

Jennifer Olson ◽

Linus Schmitz ◽

Steven N. Jeffers

Keyword(s):

United States ◽

South Carolina ◽

Sequence Similarity ◽

Morphological Characteristics ◽

The United States ◽

Universal Primers ◽

Broad Host Range ◽

Pathogenicity Test ◽

First Report ◽

Foliage Blight

Chrysanthemum (Chrysanthemum × morifolium) plants exhibiting stem and foliage blight were observed in a commercial nursery in eastern Oklahoma in June 2019. Disease symptoms were observed on ~10% of plants during a period of frequent rain and high temperatures (26-36°C). Dark brown lesions girdled the stems of symptomatic plants and leaves were wilted and necrotic. The crown and roots were asymptomatic and not discolored. A species of Phytophthora was consistently isolated from the stems of diseased plants on selective V8 agar (Lamour and Hausbeck 2000). The Phytophthora sp. produced ellipsoid to obpyriform sporangia that were non-papillate and persistent on V8 agar plugs submerged in distilled water for 8 h. Sporangia formed on long sporangiophores and measured 50.5 (45-60) × 29.8 (25-35) µm. Oospores and chlamydospores were not formed by individual isolates. Mycelium growth was present at 35°C. Isolates were tentatively identified as P. drechsleri using morphological characteristics and growth at 35°C (Erwin and Ribeiro 1996). DNA was extracted from mycelium of four isolates, and the internal transcribed spacer (ITS) region was amplified using universal primers ITS 4 and ITS 6. The PCR product was sequenced and a BLASTn search showed 100% sequence similarity to P. drechsleri (GenBank Accession Nos. KJ755118 and GU111625), a common species of Phytophthora that has been observed on ornamental and vegetable crops in the U.S. (Erwin and Ribeiro 1996). The gene sequences for each isolate were deposited in GenBank (accession Nos. MW315961, MW315962, MW315963, and MW315964). These four isolates were paired with known A1 and A2 isolates on super clarified V8 agar (Jeffers 2015), and all four were mating type A1. They also were sensitive to the fungicide mefenoxam at 100 ppm (Olson et al. 2013). To confirm pathogenicity, 4-week-old ‘Brandi Burgundy’ chrysanthemum plants were grown in 10-cm pots containing a peat potting medium. Plants (n = 7) were atomized with 1 ml of zoospore suspension containing 5 × 103 zoospores of each isolate. Control plants received sterile water. Plants were maintained at 100% RH for 24 h and then placed in a protected shade-structure where temperatures ranged from 19-32°C. All plants displayed symptoms of stem and foliage blight in 2-3 days. Symptoms that developed on infected plants were similar to those observed in the nursery. Several inoculated plants died, but stem blight, dieback, and foliar wilt were primarily observed. Disease severity averaged 50-60% on inoculated plants 15 days after inoculation. Control plants did not develop symptoms. The pathogen was consistently isolated from stems of symptomatic plants and verified as P. drechsleri based on morphology. The pathogenicity test was repeated with similar results. P. drechsleri has a broad host range (Erwin and Ribeiro 1996; Farr et al. 2021), including green beans (Phaseolus vulgaris), which are susceptible to seedling blight and pod rot in eastern Oklahoma. Previously, P. drechsleri has been reported on chrysanthemums in Argentina (Frezzi 1950), Pennsylvania (Molnar et al. 2020), and South Carolina (Camacho 2009). Chrysanthemums are widely grown in nurseries in the Midwest and other regions of the USA for local and national markets. This is the first report of P. drechsleri causing stem and foliage blight on chrysanthemum species in the United States. Identifying sources of primary inoculum may be necessary to limit economic loss from P. drechsleri.

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First Report of Leaf Blight and Stem Canker of Pachysandra terminalis Caused by Pseudonectria pachysandricola in Korea

Plant Disease ◽

10.1094/pdis-09-11-0813 ◽

2012 ◽

Vol 96 (2) ◽

pp. 287-287

Author(s):

K. S. Han ◽

J. H. Park ◽

S. E. Cho ◽

H. D. Shin

Keyword(s):

United States ◽

Its Region ◽

Stem Canker ◽

The United States ◽

Culture Collection ◽

Leaf Blight ◽

First Report ◽

Cornell University ◽

Plastic Bags ◽

Young Leaves

Pachysandra terminalis Siebold & Zucc., known as Japanese pachysandra, is a creeping evergreen perennial belonging to the family Buxaceae. In April 2011, hundreds of plants showing symptoms of leaf blight and stem canker with nearly 100% incidence were found in a private garden in Suwon, Korea. Plants with the same symptoms were found in Seoul in May and Hongcheon in August. Affected leaves contained tan-to-yellow brown blotches. Stem and stolon cankers first appeared as water soaked and developed into necrotic lesions. Sporodochia were solitary, erumpent, circular, 50 to 150 μm in diameter, salmon-colored, pink-orange when wet, and with or without setae. Setae were hyaline, acicular, 60 to 100 μm long, and had a base that was 4 to 6 μm wide. Conidiophores were in a dense fascicle, not branched, hyaline, aseptate or uniseptate, and 8 to 20 × 2 to 3.5 μm. Conidia were long, ellipsoid to cylindric, fusiform, rounded at the apex, subtruncate at the base, straight to slightly bent, guttulate, hyaline, aseptate, 11 to 26 × 2.5 to 4.0 μm. A single-conidial isolate formed cream-colored colonies that turned into salmon-colored colonies on potato dextrose agar (PDA). Morphological and cultural characteristics of the fungus were consistent with previous reports of Pseudonectria pachysandricola B.O. Dodge (1,3,4). Voucher specimens were housed at Korea University (KUS). Two isolates, KACC46110 (ex KUS-F25663) and KACC46111 (ex KUS-F25683), were accessioned in the Korean Agricultural Culture Collection. Fungal DNA was extracted with DNeasy Plant Mini DNA Extraction Kits (Qiagen Inc., Valencia, CA). The complete internal transcribed spacer (ITS) region of rDNA was amplified with the primers ITS1/ITS4 and sequenced using ABI Prism 337 automatic DNA sequencer (Applied Biosystems, Foster, CA). The resulting sequence of 487 bp was deposited in GenBank (Accession No. JN797821). This showed 100% similarity with a sequence of P. pachysandricola from the United States (HQ897807). Isolate KACC46110 was used in pathogenicity tests. Inoculum was prepared by harvesting conidia from 2-week-old cultures on PDA. Ten young leaves wounded with needles were sprayed with conidial suspensions (~1 × 106 conidia/ml). Ten young leaves that served as the control were treated with sterile distilled water. Plants were covered with plastic bags to maintain a relative humidity of 100% at 25 ± 2°C for 24 h. Typical symptoms of brown spots appeared on the inoculated leaves 4 days after inoculation and were identical to the ones observed in the field. P. pachysandricola was reisolated from 10 symptomatic leaf tissues, confirming Koch's postulates. No symptoms were observed on control plants. Previously, the disease was reported in the United States, Britain, Japan, and the Czech Republic (2,3), but not in Korea. To our knowledge, this is the first report of P. pachysandricola on Pachysandra terminalis in Korea. Since this plant is popular and widely planted in Korea, this disease could cause significant damage to nurseries and the landscape. References: (1) B. O. Dodge. Mycologia 36:532, 1944. (2) D. F. Farr and A. Y. Rossman. Fungal Databases. Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , September 24, 2011. (3) I. Safrankova. Plant Prot. Sci. 43:10, 2007. (4) W. A. Sinclair and H. H. Lyon. Disease of Trees and Shrubs. 2nd ed. Cornell University Press, Ithaca, NY, 2005.

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First Report of Iris yellow spot virus on Onion and Leek in Western Oregon

Plant Disease ◽

10.1094/pdis-91-4-0468a ◽

2007 ◽

Vol 91 (4) ◽

pp. 468-468 ◽

Cited By ~ 5

Author(s):

D. H. Gent ◽

R. R. Martin ◽

C. M. Ocamb

Keyword(s):

United States ◽

Disease Incidence ◽

The United States ◽

Yellow Spot ◽

Onion Bulb ◽

Spot Virus ◽

First Report ◽

Seed Crop ◽

Onion Seed ◽

Seed Crops

Onion (Allium cepa) and leek (Allium porrum) are grown on approximately 600 ha in western Oregon annually for bulb and seed production. During July and August of 2006, surveys of onion bulb crops and onion and leek seed crops in western Oregon found plants with symptoms of elongated to diamond-shaped, straw-colored lesions characteristic of those caused by Iris yellow spot virus (IYSV) (1–4). Symptomatic plants were collected from fields of an onion bulb crop, an onion seed crop, and two leek seed crops located in Marion County. The onion bulb crop had been planted in the spring of 2006, and the onion and leek seed crops had been planted in the fall of 2005, all direct seeded. Cultivar names were not provided for proprietary purposes. Symptomatic plants in the onion bulb crop and leek seed crop generally were found near the borders of the field. Disease incidence was less than 5% and yield losses in these crops appeared to be negligible. In the onion seed crop, symptomatic plants were found throughout the field and disease incidence was approximately 20%. Approximately 1% of the onion plants in this field had large necrotic lesions that caused the seed stalks (scapes) to lodge. The presence of IYSV was confirmed from symptomatic leaves and scapes by ELISA (Agdia Inc., Elkhart, IN) using antiserum specific to IYSV. RNA was extracted from symptomatic areas of onion leaves and scapes, and a portion of the nucleocapsid gene was amplified by reverse transcription-PCR. The amplicons were sequenced and found to share more than 99% nucleotide and amino acid sequence identity with an onion isolate of IYSV from the Imperial Valley of California (GenBank Accession No. DQ233475). In the Pacific Northwest region of the United States, IYSV has been confirmed in the semi-arid regions of central Oregon (1), central Washington (2), and the Treasure Valley of eastern Oregon and southwest Idaho (3). To our knowledge, this is the first report of the disease on a host crop in the mild, maritime region west of the Cascade Mountain Range and the first report of IYSV on leek seed crops in the United States, which complements a simultaneous report of IYSV on commercial leek in Colorado. The presence of IYSV may have implications for the iris and other ornamental bulb industries in western Oregon and western Washington. This report underscores the need for further research to determine the impact of the disease on allium crops and other hosts and the development of effective management programs for IYSV and the vector, Thrips tabaci. References: (1) F. J. Crowe and H. R. Pappu. Plant Dis. 89:105, 2005. (2) L. J. du Toit et al. Plant Dis. 88:222, 2004. (3) J. M. Hall et al. Plant Dis. 77:952, 1993. (4) H. F. Schwartz et al. Plant Dis. 91:113, 2007.

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First Report of Downy Mildew Caused by Plasmopara obducens on Impatiens in California

Plant Disease ◽

10.1094/pdis.2004.88.8.909b ◽

2004 ◽

Vol 88 (8) ◽

pp. 909-909 ◽

Cited By ~ 14

Author(s):

S. N. Wegulo ◽

S. T. Koike ◽

M. Vilchez ◽

P. Santos

Keyword(s):

United States ◽

Downy Mildew ◽

Disease Incidence ◽

Leaf Tissue ◽

The United States ◽

Plant Diseases ◽

Single Type ◽

First Report ◽

Commercial Grower ◽

Impatiens Walleriana

During February 2004, diseased double impatiens (Impatiens walleriana) plants were received from a commercial grower in southern California. The upper surfaces of symptomatic leaves were pale yellow with no distinct lesions. Diseased leaves later wilted, and severely affected leaves abscised from the stem. At the nursery, only double impatiens plants in the Fiesta series were infected, and some cultivars were more heavily infected than others. Disease incidence in cv. Sparkler Hot pink was nearly 100%. The interior of infected leaves was colonized by coenocytic mycelium. A conspicuous white growth was observed only on the underside of leaves. Sporangiophores were hyaline, thin walled, emergent from stomata, and had slightly swollen bases. Sporangiophore branching was distinctly monopodial. Smaller sporangiophore branches were arranged at right angles to the supporting branches, and tips of branches measured 8 to 14 μm long. Sporangia were ovoid and hyaline with a single pore on the distal ends. Distal ends of sporangia were predominantly flat but occasionally had a slight papilla. Short pedicels were present on the attached ends. Sporangia measured 19.4 to 22.2 (-25.0) μm × 13.9 to 16.7 (-19.4) μm. Oospores were not observed in leaf tissue. On the basis of symptoms and morphology of the organism, the pathogen was identified as Plasmopara obducens J. Schröt. Pathogenicity tests were done on double type cvs. Fiesta, Tioga Red, and Tioga Cherry Red and on single type cvs. Cajun Watermelon and Accent Lilac. Plants were spray inoculated with sporangiospore suspensions (1 × 104 sporangiospores per milliliter), incubated for 24 h in a dew chamber (18 to 20°C), and then maintained in a greenhouse (22 to 24°C). Symptoms and signs of downy mildew developed after 12 days only on inoculated cv. Fiesta plants, and the pathogen morphology matched that of the originally observed pathogen. Nontreated control plants did not develop downy mildew. To our knowledge, this is the first report of downy mildew on impatiens in California. P. obducens is one of two causal agents of downy mildew of impatiens (2,4). The other pathogen, Bremiella sphaerosperma, has dichotomous sporangiophore branching and causes lesions with well-defined margins (2,4). In the United States, the disease has been recorded in the eastern and northeastern states and in Indiana, Minnesota, Mississippi, Montana, and Wisconsin (3). In Canada, the disease has been recorded in Manitoba and Quebec (1). References: (1) I. L. Conners. An Annotated Index of Plant Diseases in Canada and Fungi Recorded on Plants in Alaska, Canada, and Greenland. Research Branch, Canada Department of Agriculture, Publication 1251, 1967. (2) O. Constantinescu. Mycologia 83:473, 1991. (3) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, 1989. (4) G. W. Wilson. Bull. Torrey Bot. Club 34:387, 1907.

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First Report of Apple Hammerhead Viroid in the United States, Japan, Italy, Spain, and New Zealand

Plant Disease ◽

10.1094/pdis-04-18-0557-pdn ◽

2018 ◽

Vol 102 (12) ◽

pp. 2670-2670 ◽

Cited By ~ 6

Author(s):

S. A. Szostek ◽

A. A. Wright ◽

S. J. Harper

Keyword(s):

United States ◽

New Zealand ◽

The United States ◽

First Report

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First Report of Postharvest Fruit Rot in Persimmon Caused by Phacidiopycnis washingtonensis in Italy

Plant Disease ◽

10.1094/pdis-94-6-0788b ◽

2010 ◽

Vol 94 (6) ◽

pp. 788-788 ◽

Cited By ~ 2

Author(s):

A. Garibaldi ◽

D. Bertetti ◽

M. T. Amatulli ◽

M. L. Gullino

Keyword(s):

United States ◽

Its Region ◽

The United States ◽

Fruit Rot ◽

Diospyros Kaki ◽

Pathogenicity Test ◽

Conidial Suspension ◽

First Report ◽

Pathogenicity Tests ◽

Phacidiopycnis Washingtonensis

Persimmon (Diospyros kaki L.) is widely grown in Italy, the leading producer in Europe. In the fall of 2009, a previously unknown rot was observed on 3% of fruit stored at temperatures between 5 and 15°C in Torino Province (northern Italy). The decayed area was elliptical, firm, and appeared light brown to dark olive-green. It was surrounded by a soft margin. The internal decayed area appeared rotten, brown, and surrounded by bleached tissue. On the decayed tissue, black pycnidia that were partially immersed and up to 0.5 mm in diameter were observed. Light gray conidia produced in the pycnidia were unicellular, ovoid or lacriform, and measured 3.9 to 6.7 × 2.3 to 3.5 (average 5.0 × 2.9) μm. Fragments (approximately 2 mm) were taken from the margin of the internal diseased tissues, cultured on potato dextrose agar (PDA), and incubated at temperatures between 23 and 26°C under alternating light and darkness. Colonies of the fungus initially appeared ash colored and then turned to dark greenish gray. After 14 days of growth, pycnidia and conidia similar to those described on fruit were produced. The internal transcribed spacer (ITS) region of rDNA was amplified using the primers ITS4/ITS6 and sequenced. BLAST analysis (1) of the 502-bp segment showed a 100% similarity with the sequence of Phacidiopycnis washingtonensis Xiao & J.D. Rogers (GenBank Accession No. AY608648). The nucleotide sequence has been assigned the GenBank Accession No. GU949537. Pathogenicity tests were performed by inoculating three persimmon fruits after surface disinfesting in 1% sodium hypochlorite and wounding. Mycelial disks (10 mm in diameter), obtained from PDA cultures of one strain were placed on wounds. Three control fruits were inoculated with plain PDA. Fruits were incubated at 10 ± 1°C. The first symptoms developed 6 days after the artificial inoculation. After 15 days, the rot was very evident and P. washingtonensis was consistently reisolated. Noninoculated fruit remained healthy. The pathogenicity test was performed twice. Since P. washingtonensis was first identified in the United States on decayed apples (2), ‘Fuji’, ‘Gala’, ‘Golden Delicious’, ‘Granny Smith’, ‘Red Chief’, and ‘Stark Delicious’, apple fruits also were artificially inoculated with a conidial suspension (1 × 106 CFU/ml) of the pathogen obtained from PDA cultures. For each cultivar, three surface-disinfested fruit were wounded and inoculated, while three others served as mock-inoculated (sterile water) controls. Fruits were stored at temperatures ranging from 10 to 15°C. First symptoms appeared after 7 days on all the inoculated apples. After 14 days, rot was evident on all fruit inoculated with the fungus, and P. washingtonensis was consistently reisolated. Controls remained symptomless. To our knowledge, this is the first report of the presence of P. washingtonensis on persimmon in Italy, as well as worldwide. The occurrence of postharvest fruit rot on apple caused by P. washingtonensis was recently described in the United States (3). In Italy, the economic importance of the disease on persimmon fruit is currently limited, although the pathogen could represent a risk for apple. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) Y. K. Kim and C. L. Xiao. Plant Dis. 90:1376, 2006. (3) C. L. Xiao et al. Mycologia 97:473, 2005.

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First Report of Leaf Spot of Sesame Caused by Xanthomonas sp. In the United States

Plant Disease ◽

10.1094/pdis-03-12-0284-pdn ◽

2012 ◽

Vol 96 (8) ◽

pp. 1222-1222 ◽

Cited By ~ 2

Author(s):

T. Isakeit ◽

B. T. Hassett ◽

K. L. Ong

Keyword(s):

United States ◽

Leaf Area ◽

Its Region ◽

The United States ◽

Pcr Analysis ◽

Sterile Water ◽

First Report ◽

Genomic Dna Isolation ◽

Leaf Spots ◽

Mist Chamber

In July 2010 in Texas, extensive leaf spots (10 to 30% leaf area affected) occurred on a commercial planting of sesame (Sesamum indicum L.) in Hidalgo County and to a lesser extent (1 to 5% leaf area) on leaves of several varieties in experimental trials in Colorado and Victoria Counties. The leaf spots were light to dark brown, somewhat circular, and 1 to 3 mm in diameter. A symptomatic leaf from each of three to five plants per county was sampled for isolations. Leaves were sprayed with 70% ethanol and immediately blotted dry with a paper towel. The margins of spots (2 mm2) were excised with a scalpel and placed in a drop of sterile water for 5 min. Drops were streaked on nutrient agar (NA) and incubated at 30°C. The 12 isolations consistently yielded gram-negative, rod-shaped bacteria with yellow, translucent colonies that were visible after 2 days of incubation. The DNA of 11 isolates was extracted with the Norgen (Thorold, ON) Bacterial genomic DNA isolation kit (Cat. #17900) and the ITS region was amplified by 16S uni 1330 and 23S uni 322 anti primers (1). PCR products were treated with the ZymoResearch (Irvine, CA) DNA clean & concentrator kit (Cat. #D4003) and sequenced. With the NCBI database, a BLAST search of the 1,100 bp amplicons showed 93 to 99% identity with pathovars of either Xanthomonas oryzae or X. axonopodis (GenBank Accession Nos. CP003057.1 and CP002914.1, respectively). Amplicon sequences of the sesame isolates were deposited in GenBank as Accession Nos. JQ975037 through JQ975047. The reported species on sesame is X. campestris pv. sesami (2). To fulfill Koch's postulates, potted sesame plants (var. Sesaco 25), 15 to 20 cm tall, were sprayed until runoff with a suspension of bacteria (106 to 107 CFU/ml) from a 2-day-old NA culture. All 12 isolates were evaluated, with five to seven plants per isolate. Plants were maintained in a mist chamber in a greenhouse at 27 to 30°C and 100% relative humidity. The pathogenicity trial was repeated once. Leaf spots were first seen 7 days after inoculation and were prevalent 14 days after inoculation. All 12 isolates were pathogenic. There were no symptoms on leaves sprayed with sterile water. Bacteria that produced colonies consistent with Xanthomonas were reisolated on NA from symptomatic leaves but not from controls. The identities of three isolates were reconfirmed with PCR analysis and sequencing. In 2007, more than 2,000 ha of sesame were grown in the continental United States, with 80% of that in Texas. Currently, acreage of shatter-free varieties of sesame is increasing in arid areas of Texas, Oklahoma, and Kansas. In such areas, the yield impact of this disease is likely to be minimal, except in years with above-average rainfall. To our knowledge, this is the first report of this disease in the United States. References: (1) E. R. Gonçalves and Y. B. Rosato. Int. J. Syst. Evol. Microbiol. 52:355, 2002. (2) J. M. Young et al., New Zealand J. Agric. Res. 21:153, 1978.

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First Report of Botrytis Blight Caused by Botrytis cinerea on Platycodon grandiflorum in Italy

Plant Disease ◽

10.1094/pdis-93-9-0969b ◽

2009 ◽

Vol 93 (9) ◽

pp. 969-969

Author(s):

A. Garibaldi ◽

D. Bertetti ◽

M. L. Gullino

Keyword(s):

United States ◽

Botrytis Cinerea ◽

Its Region ◽

The United States ◽

Fluorescent Light ◽

Pathogenicity Test ◽

Commonwealth Mycological Institute ◽

Platycodon Grandiflorum ◽

First Report ◽

Bedding Plant

Platycodon grandiflorum (balloon flower), a perennial plant belonging to the Campanulaceae family, is widely grown as a bedding plant in temperate gardens. This species is characterized by the ability to bloom profusely throughout the summer into early fall and for its white to blue and pink flowers. In September 2008, symptoms of a previously unknown blight were observed in six gardens located in the Biella Province of northern Italy. When the disease developed, temperatures ranged between 15 and 22°C with frequent rains (149.8 mm of rainfall registered in September 2008 by the meteorological station of Oropa, located in the same area in which the disease appeared). Initially, leaves and petioles appeared chlorotic. Subsequently, lesions developed on the stems and flowers were sometimes affected. In each garden examined, approximately 50% of the plants were affected by the disease. A soft, gray mycelium was observed on symptomatic tissues, especially the stems. Severely infected leaves and stems eventually became completely rotted and later desiccated. Diseased tissue was excised from affected leaves, immersed in a solution containing 1% sodium hypochlorite for 10 s, and then cultured on potato dextrose agar (PDA) medium. A fungus developed that produced abundant mycelium on PDA medium when incubated under constant fluorescent light at 22 ± 1°C. Numerous sclerotia were produced on PDA plates incubated for 20 days at 8 ± 1°C. Sclerotia were dark, irregular, and measured 1 to 3.5 × 0.9 to 2.5 (average 2.1 × 1.5) mm. Conidia were smooth, ash colored, unicellular, ovoid, and measured 11 to 19 × 7 to 13 (average 15 × 11) μm. These morphological features were typical of those described for Botrytis cinerea (2). The internal transcribed spacer (ITS) region of rDNA was amplified using primers ITS4/ITS6 and sequenced. BLAST analysis (1) of the 539-bp segment showed 100% similarity with the sequence of Botryotinia fuckeliana (perfect stage of B. cinerea). The nucleotide sequence has been assigned the GenBank Accession No. GQ149480. Pathogenicity tests were performed by placing 1-cm2 fragments removed from PDA cultures of B. cinerea isolated from balloon flower on leaves of healthy potted P. grandiflorum plants (4-month-old). Five fragments were placed on each plant. Plants inoculated with PDA alone served as controls. Ten plants per treatment were used. Plants were covered with plastic bags for 5 days after inoculation and maintained in a greenhouse at temperatures between 18 and 23°C. The first foliar lesions developed on leaves 3 days after inoculation, and after 5 days, 80% of the leaves were severely infected. As the infection progressed after the inoculation, the stems also became infected. Control plants remained healthy. B. cinerea was consistently reisolated from leaf and stem lesions. The pathogenicity test was completed twice. To our knowledge, this is the first report of the presence of B. cinerea on P. grandiflorum in Italy, as well as in Europe. Blight on balloon flower attributed to Botrytis spp. was previously reported in the United States (3). References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) M. B. Ellis. Dematiaceous Hyphomycetes. Commonwealth Mycological Institute, Kew, England, 1971. (3) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St. Paul, MN, 1989.

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On the Identity of the Weedy Bittercresses (Cardamine : Brassicaceae) in United States Nurseries: Evidence from Molecules and Morphology

Weed Science ◽

10.1614/ws-d-10-00063.1 ◽

2011 ◽

Vol 59 (1) ◽

pp. 123-135 ◽

Cited By ~ 10

Author(s):

Angela R. Post ◽

Regina Ali ◽

Alexander Krings ◽

Jenny Xiang ◽

Brian R. Sosinski ◽

...

Keyword(s):

United States ◽

New Zealand ◽

Its Region ◽

The United States ◽

Nuclear Ribosomal Dna ◽

Molecular Evidence ◽

Herbarium Specimens ◽

Interacting Protein ◽

Cardamine Flexuosa ◽

Container Nurseries

Bittercress (Brassicaceae) is one of the most prolific and costly weeds of the container nursery industry. Bittercress accessions from container nurseries throughout the major production zones in the United States were examined and compared with herbarium specimens. The identity of these weedy bittercress species were further explored using sequences of the nuclear ribosomal DNA (nrDNA) internal transcribed spacer (ITS) region and the nrDNA region for the COP1-interacting protein 7 (CIP7). Four species of bittercress were detected in the nursery industry of the United States, including New Zealand bittercress, hairy bittercress, flexuous bittercress, and little bittercress. The taxon referred to here as Cardamine flexuosa With. (flexuous bittercress) likely contains two genotypes previously reported as European C. flexuosa and Asian C. flexuosa. Phylogenetic relationships between the four species we examined, particularly in relationship to flexuous bittercress, were not fully resolved by the molecular evidence generated for this study. New Zealand bittercress is nonnative and does not appear in current keys to the species for the United States. Flexuous bittercress is also an alien species, which appears in some U.S. keys but not in all. To aid nurserymen and botanists in identification of these four closely related bittercress species, a key was developed and is accompanied by detailed descriptions and illustrations.

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