First Report of Clubroot of Eruca sativa Caused by Plasmodiophora brassicae in Brazil

Eruca sativa Mill. (family Brassicaceae), with its origin in western Asia, is a culinary and pharmacological species cultivated in Europe, Brazil, and other countries. In the United States, it is a minor crop known as arugula or roquette. Clubroot on E. sativa has not been reported in Brazil and has been reported once in the United States in 1914 (1,2,3). On several occasions since 2000, stunted and wilted plants (cv. Rúcula Cultivada) were collected from growers' fields and greenhouses that had been direct-seeded in Vargem Bonita, DF (two fields and one greenhouse) and Quatro Barras, PR (two fields). The infected arugula crops were found in areas where other plants from the genus Brassica were traditionally cultivated. Disease incidence in individual fields varied from 20 to 80%. Diseased plants were severely affected with hypertrophic, malformed roots, and root galls resembling Woronin's description (4). Plasmodia and resting spores in thin sections prepared from root galls were observed with compound and electron microscopes. Pathogenicity tests were conducted on arugula and Brassica pekinensis (Lour.) Rupr. (universal host) with inoculum from naturally infected arugula. The soil of potted test plants at the four-to-five-leaf stage was drenched with a suspension of resting spores. Symptoms identical to those observed on the original plants were produced on all inoculated plants 2 to 3 weeks after inoculation. Control plants remained symptomless. The pathogen was positively identified as Plasmodiophora brassicae Wor. with the combination of macroscopic and microscopic symptoms and signs of the disease and pathogen. P. brassicae was first reported in Brazil in 1965 in the state of São Paulo and in the 1980s in Distrito Federal on several members of the Brassicae. To our knowledge, this is the first report of P. brassicae infecting E. sativa in Brazil. Arugula is a susceptible host and should not be planted on P. brassicae-infested land. References: (1) D. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St. Paul, MN. 1989. (2) D. F. Farr et al. Fungal Databases. Systematic Botany and Mycology Laboratory, On-line publication. ARS, USDA, 2003. (3) J. S. Karling. The Plasmodiophorales. Published by J. S. karling, NY. 1942. (4) M. S. Woronin. Plasmodiophora brassicae the Cause of Cabbage Hernia. Phytopathological Classics 4. The American Phytopathological Society, Ithaca, NY, 1934.

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First Report of Clubroot on Canola Caused by Plasmodiophora brassicae in North Dakota

Plant Disease ◽

10.1094/pdis-04-14-0430-pdn ◽

2014 ◽

Vol 98 (10) ◽

pp. 1438-1438 ◽

Cited By ~ 10

Author(s):

K. Chittem ◽

S. M. Mansouripour ◽

L. E. del Río Mendoza

Keyword(s):

United States ◽

North Dakota ◽

Plasmodiophora Brassicae ◽

The United States ◽

Soil Samples ◽

Pcr Analysis ◽

Infested Soil ◽

First Report ◽

Resting Spores ◽

Pathogenicity Tests

North Dakota leads the United States in canola (Brassica napus L.) production (4). A canola field with a distinct patch of dead plants spreading over an area of approximately 0.4 ha was detected in Cavalier County, North Dakota, in early September 2013. Numerous spots within the patch had plant mortalities >80%. Dead plants pulled from the soil had roots with severe galling and clubbing. Clubbed roots were brittle and disintegrated easily when pressed between fingers. Root and soil samples collected at several locations within and outside the affected patch were pooled in separate groups. All plants collected in the patch were symptomatic but those collected outside were not. In the lab, total genomic DNA from three symptomatic and two healthy root samples was extracted using standard procedures and freehand slices were prepared for observation with a compound microscope. Also, DNA from pooled soil samples was extracted using FastDNA Spin Kit for Soil (MP Biomedicals, Solon, OH). Round resting structures ranging from 2.2 to 4.2 μm in diameter were observed by microscopic examination of symptomatic root tissues. These structures resembled those typically produced by Plasmodiophora brassicae Woronin. This initial identification was later confirmed through PCR analysis using the species specific primers TC1F/R and TC2F/R (1). PCR products of 548 bp (TC1F/R) and 519 bp (TC2F/R) were produced in the three symptomatic and two infested soil samples, confirming the presence of P. brassicae. PCR amplicons were not detected in healthy root and soil samples. Pathogenicity tests were conducted in greenhouse to fulfill Koch's postulates. Briefly, five square plastic pots (10 × 10 × 13 cm) were filled with a 10-cm layer of Sunshine Mix #1 potting mix (Fison Horticulture, Vancouver, BC, Canada) and then 1 g of ground root galls (approximately 5 × 105 resting spores) was spread evenly on its surface and covered with 2 cm of soilless mix. A similar number of pots were filled only with soilless mix and used as controls. All pots were planted with two seeds of canola cv. Westar and incubated in greenhouse conditions at 21°C and 16 h light daily. The experiment was conducted twice. Four weeks after planting, all plants in the inoculated pots had developed galls while plants in control pots were symptomless. Presence of P. brassicae resting spores in the newly developed galls was confirmed by microscopic observations and PCR. Based on the symptoms, morphology of resting spores, PCR reactions, and pathogenicity tests, we confirm the presence of P. brassicae on canola. While P. brassicae has been reported as widespread in North America (2), to our knowledge, this is the first report of clubroot on canola in North Dakota and the United States. Clubroot became the most important disease affecting canola production in central Alberta, Canada, within 5 years of its discovery in 2003 (3); since then, the disease has been detected in Saskatchewan and Manitoba (3), Canadian provinces that share borders with North Dakota. Considering the difficulties in management of clubroot, measures should be initiated to limit the spread of the disease before it could pose a threat to United States canola production. References: (1) T. Cao et al. Plant Dis. 91:80, 2007. (2) G. Dixon J. Plant Growth Regul. 28:194, 2009. (3) S. Strelkov and S. Hwang. Can. J. Plant Pathol. 36(S1):27, 2014. (4) USDA-NASS, Ag. Statistics No. 81, 2012.

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First Report of Powdery Mildew Caused by Erysiphe aquilegiae var. aquilegiae on Aquilegia flabellata in Italy

Plant Disease ◽

10.1094/pdis.2004.88.6.681a ◽

2004 ◽

Vol 88 (6) ◽

pp. 681-681

Author(s):

A. Garibaldi ◽

D. Bertetti ◽

M. L. Gullino

Keyword(s):

United States ◽

Powdery Mildew ◽

The United States ◽

Northern Italy ◽

American Phytopathological Society ◽

First Report ◽

Powdery Mildews ◽

The Family ◽

White Mycelium ◽

The University

Aquilegia flabellata Sieb. and Zucc. (columbine) is a perennial garden species belonging to the family Ranunculaceae. During the summer of 2003, a severe outbreak of a previously unknown powdery mildew was observed in several gardens near Biella (northern Italy). Upper surfaces of leaves were covered with a white mycelium and conidia, and as the disease progressed infected leaves turned yellow and died. Foot cell was cylindric and appressorium lobed. Conidia were hyaline, ellipsoid, and measured 31.2 to 47.5 × 14.4 to 33 μm (average 38.6 × 21.6 μm). Fibrosin bodies were not present. Cleistothecia were globose, brown, had simple appendages, ranged from 82 to 127 (average 105) μm in diameter, and contained one to two asci. Ascocarp appendages measured five to eight times the ascocarp diameter. Asci were cylindrical (ovoidal) and measured 45.3 to 58.2 × 30.4 to 40.2 μm. Ascospores (three to four per ascus) were ellipsoid or cylindrical and measured 28.3 to 31.0 × 14.0 to 15.0 μ;m. On the basis of its morphology, the pathogen was identified as Erysiphe aquilegiae var. aquilegiae (1). Pathogenicity was confirmed by gently pressing diseased leaves onto leaves of five, healthy A. flabellata plants. Five noninoculated plants served as controls. Inoculated and noninoculated plants were maintained in a garden where temperatures ranged between 20 and 30°C. After 10 days, typical powdery mildew symptoms developed on inoculated plants. Noninoculated plants did not show symptoms. To our knowledge, this is the first report of the presence of powdery mildew on Aquilegia flabellata in Italy. E. communis (Wallr.) Link and E. polygoni DC. were reported on several species of Aquilegia in the United States (2), while E. aquilegiae var. aquilegiae was previously observed on A. flabellata in Japan and the former Union of Soviet Socialist Republics (3). Specimens of this disease are available at the DIVAPRA Collection at the University of Torino. References: (1) U. Braun. Nova Hedwigia, 89:700, 1987. (2) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St Paul, MN, 1989. (3) K. Hirata. Host Range and Geographical Distribution of the Powdery Mildews. Faculty of Agriculture, Niigata University, 1966.

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First Report of Powdery Mildew, Caused by an Oidium sp., on Poinsettia in California

Plant Disease ◽

10.1094/pdis.1998.82.1.128a ◽

1998 ◽

Vol 82 (1) ◽

pp. 128-128 ◽

Cited By ~ 3

Author(s):

S. T. Koike ◽

G. S. Saenz

Keyword(s):

United States ◽

Powdery Mildew ◽

Pacific Northwest ◽

The United States ◽

Euphorbia Pulcherrima ◽

American Phytopathological Society ◽

First Report ◽

The Pacific ◽

Uninoculated Control ◽

Alternative Identification

In December 1996 and January 1997, powdery mildew was observed on potted poinsettia (Euphorbia pulcherrima Willd. ex Klotzsch) plants in Monterey County, CA. Mycelia were observed on stems, petioles, mature and immature leaves, and bracts. Severely diseased leaves became twisted and bent and senesced prematurely. The white mycelia were conspicuous, epiphytic, and amphigenous; hyphae measured 4.6 to 6.9 μm in diameter. Growth initially was in patches but eventually became effused. Appressoria were slightly lobed to lobed and sometimes opposite. Conidiophore foot cells were cylindrical, sometimes bent at the base, and slightly flexuous to flexuous. Foot cells measured 30.0 to 46.2 μm × 5.8 to 6.9 μm and were followed by one to two shorter cells. Conidia were cylindrical to slightly doliform and measured 25.4 to 32.3 μm × 11.6 to 18.5 μm. The length-to-width ratios of conidia generally were greater than 2.0. Conidia were produced singly, placing the fungus in the Pseudoidium-type powdery mildew group. Conidia germinated at the ends, and no fibrosin bodies were observed. Cleistothecia were not found. The fungus was identified as an Oidium species. Pathogenicity was demonstrated by gently pressing infected leaves having abundant sporulation onto leaves of potted poinsettia plants (cvs. Freedom Red, Peter Star Marble, and Nutcracker White), incubating the plants in a moist chamber for 48 h, and then maintaining plants in a greenhouse. After 12 to 14 days, powdery mildew colonies developed on the inoculated plants, and the pathogen was morphologically identical to the original isolates. Uninoculated control plants did not develop powdery mildew. This is the first report of powdery mildew on poinsettia in California. This fungus appears similar to Microsphaera euphorbiae but has longer, slightly flexuous foot cells that do not match the description for M. euphorbiae (1,2). An alternative identification would be Erysiphe euphorbiae; however, there are no available mitosporic descriptions for morphological comparisons (1,2). In the United States, powdery mildew of poinsettia previously has been reported in various states in the Pacific Northwest, Midwest, and Northeast. References: (1) U. Braun. Beih. Nova Hedwigia 89:1, 1987. (2) D. F. Farr et al. 1989. Fungi on Plants and Plant Products in the United States. American Phytopathological Society, St. Paul, MN.

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First Report of Collar and Root Rot Caused by Phytophthora nicotianae on Daphne odora in Italy

Plant Disease ◽

10.1094/pdis-93-8-0848a ◽

2009 ◽

Vol 93 (8) ◽

pp. 848-848

Author(s):

A. Garibaldi ◽

D. Bertetti ◽

M. L. Gullino

Keyword(s):

United States ◽

Root Rot ◽

The United States ◽

Phytophthora Nicotianae ◽

Control Treatment ◽

Peat Moss ◽

Late Winter ◽

American Phytopathological Society ◽

First Report ◽

Daphne Odora

Daphne odora is becoming popular in gardens because of its variegated foliage and fragrant flowers in late winter and early spring. During October of 2008 in a commercial nursery near Maggiore Lake (Verbano-Cusio-Ossola Province) in northwestern Italy, plants of D. odora showed extensive chlorosis and root rot. Diseased plants eventually wilted and died, dropping leaves in some cases. Most frequently, wilted leaves persisted on stems. At the soil level, dark brown-to-black water-soaked lesions that coalesced often girdled the stem. All of the crown and root system was affected. Disease was widespread and severe with 70% of 2,500 potted plants being affected. A Phytophthora-like organism was isolated consistently on a medium selective for oomycetes (4) after disinfestation of lower stem and root pieces of D. odora for 1 min in a solution containing 1% NaOCl. Tissue fragments of 1 mm2 were excised from the margins of the lesions and plated. The pathogen was identified based on morphological and physiological features as Phytophthora nicotianae (= P. parasitica) (2). Sporangia were produced for identification by growing a pure culture in sterilized soil extract solution at neutral pH (obtained by shaking and then centrifuging 300 g of soil in 1 liter of distilled water). They were spherical to ovoid, papillate, and measured 39.2 to 54.5 × 31.7 to 41.7 μm (average 44.8 × 34.5 μm). Papillae measured 2.4 to 4.9 μm (average 3.7 μm). Chlamydospores were spherical with a diameter ranging from 15.8 to 36.1 μm (average 25.4 μm). The internal transcribed spacer (ITS) region of rDNA of a single isolate was amplified using primers ITS4/ITS6 and sequenced. BLAST analysis (1) of the 804-bp segment showed a 100% homology with the sequence of P. nicotianae EF140988. The nucleotide sequence has been assigned GenBank No. FJ843100. Pathogenicity of two isolates obtained from infected plants was confirmed by inoculating 12-month-old plants of D. odora. Both isolates were grown for 15 days on a mixture of 70:30 wheat/hemp kernels and then 80 g/liter of the inoculum was mixed into a substrate containing sphagnum peat moss/pumice/pine bark/clay (50:20:20:10 vol/vol). One plant per 3-liter pot was transplanted into the substrate and constituted the experimental unit. Three replicates were used for each isolate and noninoculated control treatment; the trial was repeated once. All plants were kept in a greenhouse at temperatures from 20 to 25°C. Plants inoculated with isolate no. 1 developed symptoms of chlorosis and root rot within 14 days and then a wilt rapidly followed. Isolate no. 2 was less aggressive causing the same symptoms within 20 days. Control plants remained symptomless. P. nicotianae consistently was reisolated from inoculated plants. Previously, P. nicotianae (= P. parasitica) has been reported in several states of the United States on D. odora (3). To our knowledge, this is the first report of P. nicotianae on D. odora in Italy. The economic importance of the disease is low because of the limited number of farms that grow this crop in Italy, although spread could increase as the popularity of plantings expand. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997 (2) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St Paul, MN, 1996. (3) D. F. Farr et al. Fungi on Plants and Products in the United States. The American Phytopathological Society, St Paul, MN, 1989. (4) H. Masago et al. Phytopathology, 67:425, 1977.

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First Report of Petunia Blight Caused by Choanephora cucurbitarum in the United States

Plant Disease ◽

10.1094/pdis.2003.87.6.751c ◽

2003 ◽

Vol 87 (6) ◽

pp. 751-751 ◽

Cited By ~ 4

Author(s):

G. E. Holcomb

Keyword(s):

United States ◽

Morphological Characteristics ◽

The United States ◽

Plant Diseases ◽

Disease Spread ◽

American Phytopathological Society ◽

First Report ◽

Whole Plant ◽

Cloudy Weather ◽

Choanephora Cucurbitarum

A blight (wet rot) of petunia (Petunia ×hybrida Hort. Vilm.-Andr.) was observed in a wholesale propagation nursery in Baton Rouge, LA in September 2002. The grower reported that plants wilted and then completely rotted. The disease occurred during a period of hot, humid, and cloudy weather. Approximately 100 flats of flowering-age plants of cvs. Rose and White Madness were destroyed. No fungal sporulation was noticed on dead plants, but occasional strands of white mycelium were observed. The grower's use of azoxystrobin, iprodione, and thiophanate methyl plus mancozeb fungicides during current and past outbreaks of this disease did not prevent disease spread, but disease activity stopped after temperature and humidity dropped in early October. A fungus that produced white aerial mycelia that later developed light yellow areas and also black aerial spore masses was consistently isolated from diseased tissue placed on acidified potato dextrose agar (APDA). The fungus was identified as Choanephora cucurbitarum (Berk. & Ravenel) Thaxt. on the basis of cultural and morphological characteristics (3). Sporangiola were ellipsoid, pale brown to reddish brown with distinct longitudinal striations and measured 15 to 20 × 9 to 14 μm. Sporangiospores were broadly ellipsoid, pale brown to reddish brown, indistinctly striate with fine, hyaline polar appendages, and measured 16 to 34 × 7 to 12 μm. Spore measurements were within the range previously given for C.cucurbitarum (3). Pathogenicity tests were performed by misting a mixture of sporangiola and sporangiospores (25,000 to 70,000 per ml of water taken from 7- to 10-day-old cultures grown on APDA) on flowering-age petunia plants (cvs. Rose Madness, White Madness, and Dreams Pink). Tests were repeated twice. Inoculated plants and uninoculated control plants (2 to 4 of each treatment in each test) were held in a dew chamber at 28°C for 48 h and then moved to a greenhouse. Within 48 h after inoculation, plants developed water-soaked lesions on flowers, leaves, and stems, then wilted and rotted. Uninoculated plants remained disease free except for several that developed disease symptoms in the first test, apparently from the presence of natural inoculum on healthy-appearing plants that were obtained from the nursery where the disease was found. Koch's postulates were completed by reisolation of the pathogen from diseased inoculated plants. C. cucurbitarum (1) and C. infundibulifera (Curr.) Sacc. (2) have been reported to cause flower blight of petunia in the United States and whole plant blight (wet rot) of petunia in Japan (4). To our knowledge, this is the first report of C. cucurbitarum causing whole plant blight of petunia in the United States. References: (1) M. L. Daughtrey et al. Choanephora wet rot of poinsettia. Page 15 in: Compendium of Flowering Potted Plant Diseases. The American Phytopathological Society, St. Paul, MN, 1995. (2) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St. Paul, MN, 1989. (3) P. M. Kirk. Mycological Paper 152:1, 1984. (4) J. Takeuchi and H. Horie. Jpn. J. Phytopathol. 66:72, 2000.

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First Report of Sclerotinia Stem Rot Caused by Sclerotinia sclerotiorum on Hibiscus trionum in New York

Plant Disease ◽

10.1094/pdis-93-6-0673a ◽

2009 ◽

Vol 93 (6) ◽

pp. 673-673

Author(s):

J. Strauss ◽

H. R. Dillard

Keyword(s):

United States ◽

Sclerotinia Sclerotiorum ◽

The United States ◽

Potato Dextrose Agar ◽

Stem Rot ◽

Stem Tissue ◽

Sclerotinia Stem Rot ◽

American Phytopathological Society ◽

First Report ◽

Hibiscus Trionum

Hibiscus trionum L. (Venice mallow) is an annual weed widely distributed in the United States. In September of 2008, Venice mallow plants with bleached stems and necrotic tissues were observed in a commercial field of cabbage (Brassica oleracea L. cv. Moreton) in Geneva, NY. White, cottony mycelium and dark sclerotia were readily found on the stems and in the stem pith. Cabbage plants in direct contact with diseased Venice mallow also displayed signs and symptoms of infection by Sclerotinia sclerotiorum (Lib.) de Bary. Sclerotia from within diseased Venice mallow stems were placed in 9-cm-diameter petri plates on potato dextrose agar amended with 0.1 g/liter each of chloramphenicol and streptomycin (ABPDA) and incubated at room temperature. In addition, diseased stem tissue was surface disinfested for 3 min in 0.525% sodium hypochlorite solution, rinsed for 3 min in sterile distilled water, and placed on ABPDA. After 5 days, hyphae from the colony margin were excised and transferred to potato dextrose agar (PDA) plates. Fungal cultures consisting of white mycelia and medium-sized (~4 mm), black, irregular sclerotia were consistently recovered and identified as S. sclerotiorum based on morphological characteristics (1). Pathogenicity of two isolates (one from a sclerotium and one from stem tissue) was determined by inoculating seven 43-day-old Venice mallow plants growing in greenhouse pots (65 mm in diameter). Mycelia plugs (7 mm in diameter) were excised from 2-day-old PDA cultures of each isolate and placed on the stems at the soil line. Seven control plants were inoculated with noncolonized PDA plugs. All plants were enclosed in plastic bags for 72 h and placed under shade in the greenhouse with temperatures from 20 to 38°C (average 27°C). Symptoms similar to those observed in the affected fields were evident within 2 days after inoculation, while control plants remained symptomless. S. sclerotiorum was successfully recovered from infected plant tissue, fulfilling Koch's postulates. The experiment was repeated with similar results. To our knowledge, this is the first report of Sclerotinia stem rot of Hibiscus trionum caused by S. sclerotiorum (2,3). References: (1) L. Buchwaldt. Sclerotinia White Mold. Page 43 in: Compendium of Brassica Diseases, 1st ed. S. R. Rimmer et al., eds. The American Phytopathological Society, St. Paul, MN, 2007. (2) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, MN, 1989. (3) C. Wehlburg et al. Index of Plant Diseases in Florida. Fla Dep. Agric. Consum. Serv. Bull. 11, 1975.

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First Report of Hendersonula toruloidea as a Foliar Pathogen of Strawberry-tree (Arbutus unedo) in Europe

Plant Disease ◽

10.1094/pdis.2000.84.4.487c ◽

2000 ◽

Vol 84 (4) ◽

pp. 487-487 ◽

Cited By ~ 1

Author(s):

P. C. Tsahouridou ◽

C. C. Thanassoulopoulos

Keyword(s):

United States ◽

The United States ◽

Northern Greece ◽

American Phytopathological Society ◽

First Report ◽

Arbutus Unedo ◽

Strawberry Tree ◽

Foliar Pathogen ◽

Pathogenicity Tests ◽

Wild Strawberry

During spring 1997 and 1998 in the area of Chalkidiki, in northern Greece, leaves of wild strawberry-tree (Arbutus unedo) were heavily spotted. Small, necrotic brown spots with light gray centers appeared on leaves, and when intense spotting was present, strong defoliation was observed. Isolations from leaves on potato dextrose agar consistently yielded a fungus that was identified as Hendersonula toruloidea (2). Pathogenicity tests on wild strawberry-tree plants were performed, yielding symptoms identical to those originally observed, and H. toruloidea was isolated consistently from inoculated leaves. No cankers appeared on the twigs of the plants, which is a consistent symptom caused by this fungus on strawberry-tree in the United States. Leaf spotting caused by H. toruloidea has been observed in Musa and Rhus spp. (1). This is the first report of H. toruloidea causing leaf spotting and defoliation of strawberry-trees in Europe. References: (1) D. F. Farr et al. 1989. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St. Paul, MN. (2) R. M. Nattrass. Br. Mycol. Soc. Trans. 18:189, 1945.

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First Report of Puccinia vincae on Vinca spp. in California

Plant Disease ◽

10.1094/pdis.2002.86.1.75b ◽

2002 ◽

Vol 86 (1) ◽

pp. 75-75 ◽

Cited By ~ 2

Author(s):

J. R. Hernández ◽

M. E. Palm Hernández ◽

T. Tidwell

Keyword(s):

United States ◽

Lower Surface ◽

The United States ◽

Eastern United States ◽

American Phytopathological Society ◽

Germ Pore ◽

First Report ◽

Plant Products ◽

Leaf Spots ◽

Vinca Major

In 2000, chlorotic leaves with inconspicuous leaf spots were observed on several Vinca major L. and V. minor L. plants in a 0.8-ha area in Woodside, CA. In August 2001, 80 to 90% of the plants were symptomatic. Uredinia measuring 2 to 3 × 1 mm were present on the lower surface of leaves. Urediniospores were ellipsoidal to oblong, 27 to 36 × 17 to 27 μm, with cinnamon-brown walls 1 to 2 μm thick, echinulate, and with three or four equatorial or slightly supraequatorial germ pores. Telia were produced in the uredinia. Teliospores were 1-septate, ellipsoidal to clavate, slightly constricted at the septum, and 34 to 45 × 19 to 30 μm. Teliospore walls were chestnut brown, 1.5 to 2.5 μm thick, and verrucose, with the verrucae sometimes in longitudinal lines. One germ pore covered by a hyaline papilla was present in each cell, at the apex in the upper cell and adjacent to the short, hyaline pedicel in the lower cell. The rust was identified as Puccinia vincae Berk. (1). P. vincae is widespread in Europe on Vinca species and is common on V. major in the eastern United States, Washington, and Idaho (2). To our knowledge, this is the first report of P. vincae on V. major in California (vouchers BPI 841363, 841364) and on V. minor in the United States (voucher BPI 841365). References: (1) J. C. Arthur. Page 324 in: Manual of Rusts in the United States and Canada. Purdue Research Foundation, Lafayette, IN, 1934. (2) D. F. Farr et al. Pages 35 and 916 in: Fungi on Plants and Plant Products in the United States. American Phytopathological Society, St. Paul, MN, 1989.

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First Report of Club Root Caused by Plasmodiophora brassicae on Canola in Australia

Plant Disease ◽

10.1094/pdis-11-11-1006-pdn ◽

2012 ◽

Vol 96 (7) ◽

pp. 1075-1075 ◽

Cited By ~ 1

Author(s):

R. K. Khangura ◽

D. W. Wright

Keyword(s):

Western Australia ◽

Plasmodiophora Brassicae ◽

Root Hairs ◽

The United States ◽

Brassica Napus L ◽

Cortical Cells ◽

First Report ◽

Modified Method ◽

Resting Spores ◽

Species Specific

In 2009, a disease survey was conducted in 97 commercial canola (Brassica napus L.) fields in Western Australia by the Department of Agriculture and Food, Western Australia (DAFWA). In about 20% of the fields from the northern agricultural region of Western Australia, small patches were observed where canola plants showed symptoms of stunting and wilting. These plants were collected and roots of affected plants were washed thoroughly and examined for the presence of root disease. Small galls and clublike structures were observed on the secondary roots and sometimes on the main root of the affected plants. Examination of thin free hand sections from the root galls revealed that several cortical cells were enlarged and full of resting spores. The diameter of resting spores ranged between 2.5 and 3.0 μm. Plasmodia and zoosporangia were also observed in the root hairs. The identity of Plasmodiophora brassicae Woronin was confirmed by PCR using a modified method of Cao et al. 2007 (1). DNA from spores and slices of the galls of 14 different samples were extracted using DNeasy plant mini kit (QIAGEN Australia) as per manufacturer's instructions. Samples were disrupted by placing them into MPBIO tube A and placed in the Fast Prep machine at speed of 6 ms–1 for 40 s. This was repeated twice. The species-specific primers TC1F (5′-GTGGTCGAACTTCATTAAATTTGGGCTCTT-3′)/TC1R (5′-TTCACCTACGGAACGTATATGTGCATGTGA-3′) and TC2F (5′-AAACAACGAGTCAGCTTGAATGCTAGTGTG-3′)/TC2R (5′-CTTTAGTTGTGTTTCGGCTAGGATGGTTCG-3′) were used (1). The primers TC1F and TC1R failed to produce a PCR product of 548-bp size but using the primers TC2F and TC2R the PCR reaction resulted in a 519- bp fragment. Seven out of 14 samples gave positive results for P. brassicae with primers TC2F and TC2R. This indicates that the P. brassicae pathotype from Western Australia may be different than the one found in Alberta, Canada. However, pathotypes of P. brassicae from brassica vegetables from Australia have been found similar to the populations of P. brassicae present in the United States (2). Pathogenicity of P. brassicae was tested by dipping roots of five 10-day-old canola plants var. Cobbler in a spore suspension (1 × 106 resting spores/ml). Roots of five control plants were dipped in sterile water. Five weeks after inoculation, small galls were observed on the roots of three inoculated plants and the control plants remained symptomless. Resting spores were recovered from the galls developed on the roots of affected plants. Presence of P. brassicae in the affected roots was further confirmed by PCR using the method described above. To our knowledge, this is the first report of club root of canola in Australia. Club root is reported from vegetable brassicas and white mustard (Sinapis alba L.) in Australia. Club root has become a serious disease of canola in Canada since its detection in Alberta in 2006 (3). The resting spores of the fungus can survive for several years in soil, and therefore, this disease could pose a significant threat to canola production in Western Australia. References: (1) Cao et al. Plant Dis. 91:80, 2007. (2) Donald et al. Ann. App. Biol. 148:239, 2006. (3) S. Streklov et al. Can. J. Plant Pathol. 28:467, 2006.

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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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