First Report of Puccinia kuehnii, Causal Agent of Orange Rust of Sugarcane, in the United States and Western Hemisphere

In June 2007, approximately 8 km east of Belle Glade, FL, a rust disease was observed on a sugarcane (a complex hybrid of Saccharum L. species) cultivar (CP 80-1743) considered resistant to brown rust caused by Puccinia melanocephala Syd. & P. Syd. Approximately 10 km south of Canal Point, FL, another cultivar (CP 72-2086), also considered resistant to P. melanocephala, was found to be infected with a rust. Samples were sent to the USDA-APHIS National Mycologist and the USDA-ARS Systematic Mycology and Microbiology Laboratory in Beltsville, MD for identification. Observed morphological features were consistent with P. kuehnii E.J. Butler. Uredinial lesions were orange and variable in size, measuring 650 to 850 × 26 to 32 μm, hypophyllous, ellipsoidal to fusiform in shape, and distinctly lighter than pustules of P. melanocephala that were present in the area along with P. kuehnii. Urediniospores were mostly obovoid to pyriform or broadly ellipsoidal, variable in size, 32 to 45 × 25 to 30 μm, and moderately echinulate with mostly evenly distributed spines 2 to 4.5 μm apart. Walls were orange-to-light cinnamon brown, 1 to 2.5 μm thick with a pronounced apical wall thickening as much as 7 μm, and 4 to 5 equatorial pores. Similar orange uredinial lesions were subsequently observed on the same two cultivars and several other cultivars, including CPCL99-1777 and CPCL01-1055, at different locations in South Florida. Telia and teliospores were not observed. The nuclear large subunit rDNA region of the rust infecting cv. CP 80-1743 (BPI 878243, GenBank Accession No. EU164549) and the ITS1, 5.8S, and ITS2 rDNA regions of the rust infecting CP 80-1743 (GenBank Accession No. EU176009) and CP 72-2086 (GenBank Accession No. EU176008) were sequenced (1,4). All sequences were identical to sequences of P. kuehnii and distinct from known sequences of P. melanocephala (4). To our knowledge, this is the first confirmed record of P. kuehnii infecting sugarcane in the Western Hemisphere, and the disease appears to be distributed widely in the South Florida sugarcane-growing area. Although listed by P. Holliday (3) as occurring in Cuba, the Dominican Republic, and Mexico, CMI map no. 215 ed. 4 (2) does not include these three countries in the known distribution of P. kuehnii. P. kuehnii has also been reported in the literature as present in Hawaii (4). However, examination of the specimen label found that the specimen cited in those papers (BPI 079624) was actually collected in Tahiti. Therefore, the report from Hawaii is erroneous. References: (1) M. C. Aime. Mycoscience 47:112, 2006. (2) CMI. Distribution Maps of Plant Diseases. No. 215, ed. 4. CAB International, Wallingford, UK, 1981. (3) P. Holliday. Fungus Diseases of Tropical Crops. Cambridge University Press, Cambridge, 1980. (4) E. V. Virtudazo et al. Mycoscience 42:447, 2001.

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First Report of Orange Rust of Sugarcane Caused by Puccinia kuehnii in Mexico, El Salvador, and Panama

Plant Disease ◽

10.1094/pdis-93-12-1347b ◽

2009 ◽

Vol 93 (12) ◽

pp. 1347-1347 ◽

Cited By ~ 16

Author(s):

R. C. Flores ◽

J. R. Loyo ◽

R. A. Ojeda ◽

O. C. A. Rangel ◽

F. A. Cerón ◽

...

Keyword(s):

El Salvador ◽

Large Subunit ◽

Brown Rust ◽

Western Hemisphere ◽

Microbiology Laboratory ◽

Rust Disease ◽

First Report ◽

Rdna Sequences ◽

Large Subunit Rdna ◽

Its2 Rdna Sequence

Symptoms of sugarcane orange rust were observed on July 17, 2008 on sugarcane cvs. Mex 57-1285, Mex 61-230, and Co 301 (a clone received in Mexico in 1953) at the Centro de Investigación y Desarrollo de la Caña de Azúcar en Tuxtla Chico, Chiapas, Mexico. In El Salvador, from August 2008 through January 2009, rust symptoms were observed on cv. CP 72-2086 (previously resistant to brown rust caused by Puccinia melanocephala Syd. & P. Syd.) in 117 dispersed sugarcane-production fields in various localities of El Salvador. Likewise, rust symptoms were first observed on sugarcane cv. SP 74-8355 (more than 25% severity and considered resistant to brown rust) at Natá, Coclé Province in Panama from January to February 2008. Dried herbarium leaf samples of sugarcane rust-infected leaves collected in El Salvador and Mexico were sent to the ARS, USDA Systematic Mycology and Microbiology Laboratory in Beltsville MD for identification. Panamanian samples were collected similarly and analyzed at the CALESA Biotechnology Laboratory. Morphological features of uredinial lesions and urediniospores were distinct from those of P. melanocephala and consistent with P. kuehnii E. J. Butler observed previously on specimens from Florida, Guatemala, Costa Rica, and Nicaragua (1–3). Analysis of the ITS1, 5.8S, and ITS2 and 28S large subunit rDNA sequences of the rust on infected cvs. Mex 57-1285, Mex 61-230, and Co 301 (BPI 878930, 879139, and 879140; GenBank Accession Nos. GO283006, GO283004, and GO283005, respectively) from Mexico and cv. CP 72-2086 from three locations in El Salvador (BPI 879135, 879136, and 879137; GenBank Accession Nos. GO283009, GO283007, and GO283008, respectively) all confirmed the identification of P. kuehnii. Similar analysis of the ITS1, 5.8S, and ITS2 rDNA sequence for the rust infecting cv. SP 74-8355 (GenBank Accession No. GO281584) confirmed the identification of P. kuehnii in Panama. To our knowledge, this is the first report of P. kuehnii causing orange rust disease of sugarcane in El Salvador, Mexico, and Panama. These findings also confirm the wider distribution of orange rust in the Western Hemisphere. References: (1) E. Chavarria et al. Plant Dis. 93:425, 2009. (2) J. C. Comstock et al. Plant Dis. 92:175, 2008. (3) W. Ovalle et al. Plant Dis. 92:973, 2008.

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First Report of Colletotrichum capsici Causing Postharvest Anthracnose on Papaya in South Florida

Plant Disease ◽

10.1094/pdis-94-8-1065b ◽

2010 ◽

Vol 94 (8) ◽

pp. 1065-1065 ◽

Cited By ~ 9

Author(s):

T. L. B. Tarnowski ◽

R. C. Ploetz

Keyword(s):

The United States ◽

South Florida ◽

Plant Diseases ◽

Water Control ◽

Single Spore ◽

Tropical Fruit ◽

Sterile Needle ◽

Research And Education ◽

Production Areas ◽

The University

Postharvest anthracnose of papaya, Carica papaya, is an important disease in most production areas worldwide (2). Colletotrichum gloeosporioides causes two types of anthracnose symptoms on papaya: (i) circular, sunken lesions with pink sporulation; and (ii) sharply defined, reddish brown and sunken lesions, described as ‘chocolate spot’ (2). Colletorichum spp. were isolated from lesions of the first type on papaya fruit from the University of Florida Tropical Research and Education Center, Homestead in December 2007 and from fruit imported from Belize in March 2008 (4). Single-spore isolates were identified using colony morphology and internal transcribed spacer (ITS) and mating type (MAT1-2) sequences. Two taxa were identified in both locations: (i) C. gloeosporioides (MAT1-2; GenBank Nos. GQ925065 and GQ925066) with white-to-gray, fluffy colonies with orange sporulation and straight and cylindrical conidia; and (ii) C. capsici (ITS; GenBank Nos. GU045511 to GU045514) with sparse, fluffy, white colonies with setose acervuli and falcate conidia. In addition, in Florida, a Glomerella sp. (ITS; GenBank Nos. GU045518 and GU045520 to GU045522) was recovered with darkly pigmented colonies that produced fertile perithecia after 7 to 10 days on potato dextrose agar (PDA). In each of three experiments, mature fruit (cv. Caribbean Red) were wounded with a sterile needle and inoculated with a 15-μl drop of 0.3% water agar that contained 105 conidia ml–1 of representative isolates of each taxon. The diameters of developing lesions were measured after 7 days of incubation in the dark at 25°C, and the presence of inoculated isolates was confirmed by their recovery from lesion margins on PDA. In all experiments, C. capsici and C. gloeosporioides produced lesions that were significantly larger than those that were caused by the water control and Glomerella sp. (respectively, approximately 12, 17, 0, and <1 mm in diameter). C. gloeosporioides produced sunken lesions with dark gray centers and pink/gray sporulation, which match those previously described for anthracnose on papaya (2). In contrast, C. capsici produced dark lesions due to copious setae of this pathogen; they resembled C. capsici-induced lesions on papaya that were reported previously from the Yucatan Peninsula (3). C. capsici has also been reported to cause papaya anthracnose in Asia (4), but to our knowledge, this is the first time it has been reported to cause this disease in Florida. Since it was also recovered from fruit that were imported from Belize, it probably causes anthracnose of papaya in that country as well. Another falcate-spored species, C. falcatum, was recovered from rotted papaya fruit in Texas (1). The Glomerella sp. was recovered previously from other hosts as an endophyte and causes anthracnose lesions on passionfruit (4). However, its role as a pathogen on papaya is uncertain since it was not pathogenic in the current work; the isolates that were recovered from papaya lesions may have colonized lesions that were caused by C. capsici and C. gloeosporioides. References: (1) Anonymous. Index of Plant Diseases in the United States. U.S. Dept. of Agric. Handb. No. 165. Washington, D.C., 1960. (2) D. M. Persley and R. C. Ploetz. Page 373 in: Diseases of Tropical Fruit Crops. R. C. Ploetz, ed. CABI Publishing. Wallingford, UK, 2003. (3) R. Tapia-Tussell et al. Mol Biotechnol 40:293, 2008. (4) T. L. Tarnowski. Ph.D. diss. University Florida, Gainesville, 2009.

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First Report of Puccinia sorghi on Maize in Oman

Plant Disease ◽

10.1094/pd-90-0826c ◽

2006 ◽

Vol 90 (6) ◽

pp. 826-826 ◽

Cited By ~ 2

Author(s):

M. L. Deadman ◽

A. Al Sa'di ◽

Y. Al Maqbali ◽

S. Livingston ◽

M. C. Aime

Keyword(s):

Dna Analysis ◽

Large Subunit ◽

Plant Diseases ◽

Alternate Host ◽

Internal Transcribed Spacer Region ◽

Voucher Specimen ◽

Distribution Maps ◽

Puccinia Sorghi ◽

Green Fodder ◽

Fruit Orchards

Maize (Zea mays L.) is an important annual forage crop cultivated in the Sultanate of Oman, especially during the summer months. It is used for green fodder and grains and often intercropped in fruit orchards, especially under date palms. In April of 2005, leaf samples showing rust symptoms were collected from Samail, 100 km south of Muscat. Oval-shaped, red-brown pustules covered both sides of the leaves and yielded urediniospores typical of Puccinia sorghi Schwein. Urediniospores were roughly subglobose, measured 23 to 28 × 20 to 25 μm, echinulate, with three or four equitorial germ pores (2). Teliospores (38 to 42 × 16 to 19 μm) were observed, but few in numbers, most probably because of the time of year of collection. Pathogen identity was confirmed by nuclear ribosomal large subunit (28S) and internal transcribed spacer region 2 (ITS-2) DNA analysis (voucher sequence deposited in GenBank, Accession No. DQ345724, voucher specimen deposited in the U.S. National Fungus Collections, BPI 871134). P. sorghi has previously been reported from Yemen and Saudi Arabia (1) but not from Oman. Maize is grown throughout the year in Oman, and pathogen survival probably does not require the presence of the alternate host, nonetheless, Oxalis species are present and current research is attempting to locate and confirm the presence of the aecial stage in Oman. References: (1) CMI Distribution Maps of Plant Diseases. Map No. 279. Ed. 4. CABI, Wallingford, UK, 1978. (2) D. G. White, ed. Compendium of Corn Diseases. The American Phytopathological Society, St Paul, MN, 1999.

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Comparison of Puccinia acroptili from Eurasia and the USA

Botany ◽

10.1139/b2012-020 ◽

2012 ◽

Vol 90 (6) ◽

pp. 465-471 ◽

Cited By ~ 1

Author(s):

W.L. Bruckart ◽

F.M. Eskandari ◽

D.K. Berner ◽

M.C. Aime

Keyword(s):

Dna Sequence ◽

Sequence Data ◽

Large Subunit ◽

Single Species ◽

The United States ◽

Rust Disease ◽

Dna Sequence Data ◽

Russian Knapweed ◽

The Usa ◽

Recent Evaluation

A rust disease caused by Puccinia acroptili P. Syd. & Syd. occurs throughout the range of Russian knapweed (Rhaponticum (syn. Acroptilon) repens), including North America. Differences in teliospore dimensions had been observed previously, but not quantified, between a specimen of P. acroptili from Turkey and one from the United States of America (USA). Similar differences were found during a recent evaluation of P. acroptili for biological control of R. repens in the USA; e.g., teliospores from eight USA isolates were 2.4 µm shorter (P = 0.05) than four isolates from Eurasia (two from Turkey, and one each from Russia and Kazakhstan). This inspired the generation of additional biological and DNA sequence data to clarify the significance of these differences between USA and Eurasian isolates. Although the USA isolates were found to have shorter teliospores, as noted in the description by Savile, teliospores of the USA isolates were also significantly wider in diameter than isolates from Eurasia; the latter in contrast to Savile’s observation. Biologically, the isolates were the same; all were equally aggressive in causing disease under common greenhouse test conditions, and fertile crosses occurred between isolates regardless of source. DNA sequence analyses of the nuclear rDNA large subunit and internal transcribed spacer regions supported the notion that P. acroptili is a single species, but it also revealed that small levels of variation may exist within the species. For these reasons, it has been concluded that USA and Eurasian accessions can be considered a single species, i.e., P. acroptili. Also, Savile’s observation about differences in spore dimensions is substantiated.

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Identification and Characterization of Neofabraea kienholzii and Phlyctema vagabunda Causing Leaf and Shoot Lesions of Olive in California

Plant Disease ◽

10.1094/pdis-02-19-0277-re ◽

2019 ◽

Vol 103 (12) ◽

pp. 3018-3030 ◽

Cited By ~ 4

Author(s):

Florent P. Trouillas ◽

Mohamed T. Nouri ◽

Daniel P. Lawrence ◽

Juan Moral ◽

Renaud Travadon ◽

...

Keyword(s):

Large Subunit ◽

Signs And Symptoms ◽

The United States ◽

Molecular Data ◽

Fungal Species ◽

Early Spring ◽

Species Identity ◽

Internal Transcribed Spacer Region ◽

Olive Trees ◽

Large Subunit Rdna

California produces over 95% of the olives grown in the United States. In 2017, California’s total bearing acreage for olives was 14,570 hectares producing 192,000 tons of olives valued at $186.6 million. During the early spring of 2016, unusual leaf and shoot lesions were detected in olive trees from superhigh-density orchards in the Northern San Joaquin and Sacramento valleys of California. Affected trees displayed numerous leaf and shoot lesions developing at wounds created by mechanical harvesters. The ‘Arbosana’ cultivar was highly affected by the disease, whereas the disease was sporadic in ‘Arbequina’ and not found in ‘Koroneiki’ cultivar. Two fungal species, Neofabraea kienholzii and Phlyctema vagabunda, were found to be consistently associated with the disease, and Koch’s postulates were completed. Species identity was confirmed by morphology and molecular data of the partial large subunit rDNA, the internal transcribed spacer region, and partial beta-tubulin region. The disease signs and symptoms are described and illustrated.

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First Report of Rust Disease Caused by Puccinia sparganioides on Spartina alterniflora in Louisiana

Plant Disease ◽

10.1094/pdis-94-5-0636a ◽

2010 ◽

Vol 94 (5) ◽

pp. 636-636 ◽

Cited By ~ 2

Author(s):

R. Kaur ◽

C. Knott ◽

M. C. Aime

Keyword(s):

Spartina Alterniflora ◽

Salt Marshes ◽

Large Subunit ◽

The United States ◽

Research Station ◽

Smooth Cordgrass ◽

Rust Disease ◽

Internal Transcribed Spacer Region ◽

First Report ◽

Coastal Restoration

Spartina alterniflora Loisel. (smooth cordgrass) is the dominant plant species of intertidal salt marshes in the Atlantic and Gulf Coast regions of the United States. It is a perennial deciduous grass that can reduce and reverse coastal erosion by buffering wave energy and storm surges and by accumulating suspended solids from intertidal waters. Therefore, smooth cordgrass is utilized extensively in coastal restoration projects in Louisiana. In July 2009, smooth cordgrass leaf samples with signs and symptoms of a rust disease were collected from plant material grown at the Aquaculture Research Station near Baton Rouge, LA. Numerous hypophyllous, narrow, linear lesions were observed in which the uredinia were pale orange, erumpent, and arranged seriately. Urediniospores were yellowish to orange, obovoid to oblong, echinulate with a thickened apical wall and obscure germ pores, and measured 27.5 to 44.9 (–48.3) × 17.3 to 27.6 (–31.05) μm. Telia and teliospores were not observed. The pathogen was identified as Puccinia sparganioides Ellis & Tracy based on the DNA sequence of nuclear ribosomal large subunit (28S) and internal transcribed spacer region 2 (ITS-2) amplified with rust-specific primers (1). The sequence (deposited in GenBank as No. GU327649) was found to share 99.8% identity (1,077/1,079 bp) with sequence No. GU058027 of P. sparganioides from S. patens (Aiton) Muhl. and did not match any other species of Puccinia in GenBank. P. sparganioides has previously been reported on S. alterniflora in Connecticut, Delaware, Florida, Maine, Massachusetts, Mississippi, North Carolina, New Hampshire, Rhode Island, Vermont, and Virginia (2). To the best of our knowledge, this is the first report of P. sparganioides on S. alterniflora from Louisiana. Efforts to screen for rust-resistant lines for use in coastal restoration projects are underway to prevent land loss that could occur due to smooth cordgrass stress from infection. Voucher material (LSU00121657) has been deposited in the Bernard Lowy Mycological Herbarium (LSUM). References: (1) M. C. Aime. Mycoscience 47:112, 2006. (2) D. F. Farr and A. Y. Rossman. Fungal Databases. Systematic Mycology and Microbiology Laboratory, Online publication. ARS, USDA, October, 2009.

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First Report of Plumeria spp. Rust Caused by Coleosporium plumeriae in Louisiana and Malaysia and Catheranthus roseus, a New Host of this Rust

Plant Disease ◽

10.1094/pdis-94-2-0272c ◽

2010 ◽

Vol 94 (2) ◽

pp. 272-272 ◽

Cited By ~ 6

Author(s):

G. E. Holcomb ◽

M. C. Aime

Keyword(s):

United States ◽

Baton Rouge ◽

Pacific Islands ◽

The United States ◽

Plant Diseases ◽

Nerium Oleander ◽

Urban Landscapes ◽

Rust Disease ◽

Madagascar Periwinkle ◽

First Report

Plumeria spp., native to tropical America, are popular small trees grown widely in tropical areas of the world and as potted plants elsewhere. P. rubra and P. obtusa cultivars and hybrids are most common. A rust disease of a Plumeria sp. (likely P. rubra based on pointed leaf tips, leaves more than 18 cm (7 inches) long, and high rust susceptibility) was observed in November 2008 and again in June 2009 on homeowner plants in Baton Rouge, LA. A survey of five Baton Rouge retail nurseries in September 2009 revealed that 87% (90 of 103) of the plumeria plants were heavily infected with rust. Early symptoms included numerous 1-mm chlorotic spots on adaxial leaf surfaces followed by leaf chlorosis, necrosis, and abscission. Uredinia were numerous, mostly hypophyllous and yellowish orange. Urediniospores were catenulate, orange en masse, verrucose, globose, ovoid, ellipsoidal or angular, and measured 21.8 to 41.9 × 16.4 to 32.8 μm (average 29.4 × 22.6 μm). The rust was identified as Coleosporium plumeriae Pat. (= C. plumierae) (3). Teliospores were not found during this study. Pathogenicity tests were performed by spraying urediniospores (20,000/ml of deionized water) on three healthy Thai hybrid plumeria plants. Five leaves of each plant were misted with water and covered with plastic bags and three to five leaves were inoculated. Plants were held at 27°C for 27 h in a dew chamber and then moved outdoors. Typical rust symptoms and uredinia with urediniospores developed in 10 days on all inoculated leaves while noninoculated leaves remained healthy. Characteristics and spore measurements matched those of the rust from original infected plants. Additional plumeria rust inoculations were made to other Apocynaceae family members that included Allamanda cathartica, Catheranthus roseus (Madagascar periwinkle), Mandevilla splendens, Nerium oleander, and Vinca major. Catheranthus roseus was very susceptible to C. plumeriae with chlorotic leaf spots developing on the six inoculated plants after 8 days and uredinia with urediniospores appearing after 11 days. None of the other plant genera were susceptible to the rust. Plumeria rust was also observed on plumeria trees in urban landscapes in peninsular (Penang) and Bornean (Kota Kinabalu, Sabah) Malaysia in December 2007. To confirm identity, ~1,000 bp of nuclear rDNA 28S subunit from each (Lousiana, Penang, and Kota Kinabalu) was sequenced with rust-specific primers (1) and shared 100% identity (GenBank No. GU145555-6). Plumeria rust was first found on the island of Guadeloupe (3) and then spread to Central and South America. It has been known from Florida since 1960 under the synonym C. domingense (2), but has not been reported elsewhere in the continental United States. In more recent years, plumeria rust has spread to Hawaii, many Pacific islands, India, China, Taiwan, Thailand, Australia, and Nigeria (4). To our knowledge, this is the first report of plumeria rust from Louisiana and Malaysia and of susceptibility of another member of the Apocynaceae, Madagascar periwinkle, to C. plumeriae. Voucher material from Louisiana and Malaysia has been deposited in the Mycology Herbarium of Louisiana State University (LSUM). References: (1) M. C. Aime. Mycoscience 47:112, 2006. (2) Anonymous. Index of Plant Diseases in the United States. U.S. Dept. Agric. Handb. No. 165. Washington, D.C., 1960. (3) N. Patouillard. Bull. Soc. Mycol. Fr. 18:171, 1902. (4) C. To-Anun et al. Nat. Hist. J. Chulalongkorn Univ. 4:41, 2004.

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First Report of Fruit Rot on Hylocereus undatus Caused by Bipolaris cactivora in South Florida

Plant Disease ◽

10.1094/pdis-06-10-0406 ◽

2010 ◽

Vol 94 (12) ◽

pp. 1506-1506 ◽

Cited By ~ 8

Author(s):

T. L. B. Tarnowski ◽

A. J. Palmateer ◽

J. H. Crane

Keyword(s):

Dna Sequences ◽

The United States ◽

South Florida ◽

Plant Diseases ◽

Fruit Rot ◽

Mature Plant ◽

Commonwealth Mycological Institute ◽

Tropical Fruit ◽

First Report ◽

Hylocereus Undatus

Pitahaya (Hylocereus undatus (Haw.) Britton & Rose), a cactus grown for its edible fruit, is gaining popularity in South Florida as part of the specialty tropical fruit market. In July 2009, flowers and fruit were discovered with an uncharacterized rot. Small, circular, light brown, depressed lesions expanded to form large areas of rot on flowers and fruit in 7 to 10 days. The lesions produced large amounts of dark fungal spores. Single-spore isolates were identified morphologically and by aligning internal transcribed spacer (ITS) and glyceraldehyde-3-phosphate dehydrogenase (gpd) DNA sequences from the isolates with previously published sequences of Bipolaris, Drechslera, and Cochliobolus species. Conidia from the dark, blackish brown colonies were formed at the tips of pale golden brown, straight to flexuous conidiophores, 99 (184) 313 × 3 (6) 8 μm and slightly swollen at the apex and base. Conidia were pale-to-medium golden brown, smooth and clavate with a protuberant hilum, 24 (40) 51 × 9 (10) 13 μm, and two to four distoseptate. The isolates closely match descriptions of Bipolaris cactivora (= Drechslera cactivora) (3,4), although isolates from pitahaya had smaller conidia (30 to 65 μm) than previously reported. Conidial characteristics from a B. cactivora herbarium specimen BPI 431621 (U.S. National Fungus Collections) closely matched (29 (36) 50 × 8 (9) 11 μm, two to four distoseptate) our isolates. ITS (GenBank Accession Nox. HM598677–79) sequences aligned most closely (99.7% homology) with another B. cactivora isolate from China (GU390882), and both ITS and gpd (GenBank Accession Nos. HM598680–82) sequences indicate a close relationship to Bipolaris indica. Wounded or nonwounded mature pitahaya fruit and mature stems were inoculated with either a mycelia plug or a 15-μl 0.3% agar drop containing 105 conidia ml–1. Lesion diameters were measured after 7 days at 25°C, the fungus was reisolated on potato dextrose agar (PDA) and its identity was confirmed. Mean lesion diameters on mature fruit were 6.0 to 10.8 mm, depending on the inoculation method, and sporulation began 6 days after inoculation. On mature plant stems, wound-inoculated treatments formed 1.8 to 3.4 mm lesions, but nonwounded inoculations and controls were negative. Lesions were light tan, circular, and did not sporulate. To our knowledge, this is the first report of fruit rot caused by B. cactivora on pitahaya in Florida. The same pathogen causes stem rot of the Cactaceae in Europe and the United States (2) and a fruit rot on pitahaya in Japan (4). In Florida, it has been reported as causing a leaf spot on Portulaca oleracea (1). Our results indicate that B. cactivora causes flower and fruit rot on pitahaya, but does not seriously affect mature plant stems. The flower rot does not appear to significantly increase incidence but may provide inoculum for the fruit rot. The high incidence of fruit rot affecting commercial operations in Miami-Dade County over the past 2 years requires an effective disease management strategy. References: (1) S. A. Alfieri, Jr. et al. Bull. 14. Index of Plant Diseases in Florida (Revised). Florida Dep. Agric. Consumer Serv., Div. Plant Ind., 1984. (2) R. D. Durbin et al. Phytopathology 45:509, 1955. (3) M. B. Ellis. Page 432 in: Dematiaceous Hyphomycetes. Commonwealth Mycological Institute, Kew, England. 1971. (4) S. Taba et al. J. Gen. Plant Pathol. 73:374, 2007.

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First Report of Puccinia kuehnii, Causal Agent of Orange Rust of Sugarcane, in Guatemala

Plant Disease ◽

10.1094/pdis-92-6-0973c ◽

2008 ◽

Vol 92 (6) ◽

pp. 973-973 ◽

Cited By ~ 17

Author(s):

W. Ovalle ◽

J. C. Comstock ◽

N. C. Glynn ◽

L. A. Castlebury

Keyword(s):

Dna Sequences ◽

Large Subunit ◽

Brown Rust ◽

Morphological Features ◽

Western Hemisphere ◽

Its2 Rdna ◽

Microbiology Laboratory ◽

Relative Resistance ◽

Complex Hybrid ◽

Large Subunit Rdna

In September 2007 at Masagua, Escuintla Department, Guatemala, uredial lesions that appeared different from those of brown rust were observed on a sugarcane (a complex hybrid of Saccharum L. species) cultivar (CP 72-2086) considered resistant to brown rust caused by Puccinia melanocephala Syd. & P. Syd. Samples were sent to the USDA-ARS Systematic Mycology and Microbiology Laboratory in Beltsville, MD for identification. Observed morphological features were consistent with P. kuehnii E.J. Butler and appeared similar to orange rust samples obtained from Florida in July (2). Uredinial lesions were hypophyllous, orange, and variable in size measuring 650 to 850 × 26 to 32 μm. Urediniospores were mostly obovoid to pyriform or broadly ellipsoidal, variable in size, 32 to 45 × 25 to 30 μm, and moderately echinulate with spines evenly distributed, 3 to 5 μm apart. Urediniospore walls were orange-to-light cinnamon brown, 1 to 2.5 μm thick with a pronounced apical wall and four to five equatorial pores. Telia and teliospores were not observed. The nuclear large subunit rDNA region of the rust infecting cv. CP 72-2086 (BPI 898289, GenBank Accession No. EU344904) and the ITS1, 5.8S, and ITS2 rDNA regions (GenBank Accession No. EU543434) were sequenced (1,3). DNA sequences matched sequences of P. kuehnii in GenBank and were distinct from known sequences of P. melanocephala available in GenBank (3). Thirteen cultivars were rated as to their relative resistance using severity of orange rust symptoms; CG 96–59, CG 96–135, CP 72–1312, CP 73–1547, and CP 88–1165 were resistant; CG 96–40, CG 98–121, CP 72–2086, CP 88–1508, and CP 89–2143 were intermediate; and CG 96–52, CG 98–0115, and SP 79–2233 were susceptible. Orange rust was previously reported in Florida (2), but to our knowledge, this is the second report of its occurrence in the Western Hemisphere. References: (1) M. C. Aime. Mycoscience 47:112, 2006. (2) J. C. Comstock et al. Plant Dis. 92:175, 2008. (3) E. V. Virtudazo et al. Mycoscience 42:447, 2001.

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Gladiolus Rust Caused by Uromyces transversalis Makes First Nearctic Appearance in Florida

Plant Disease ◽

10.1094/pdis-91-9-1202b ◽

2007 ◽

Vol 91 (9) ◽

pp. 1202-1202 ◽

Cited By ~ 7

Author(s):

T. S. Schubert ◽

R. M. Leahy ◽

D. A. Davison ◽

A. J. Silagyi ◽

E. M. Killgore

Keyword(s):

United States ◽

Late Summer ◽

The United States ◽

Western Hemisphere ◽

Plant Diseases ◽

Diagnostic Process ◽

Government Printing ◽

Cut Flowers ◽

Residential Areas ◽

Exotic Pathogen

The most serious rust pathogen of gladiolus (Gladiolus × hortulanus), Uromyces transversalis, has been listed as an exotic pathogen of concern for the United States for more than 80 years (4). Native to South Africa, the pathogen was reported in the Western Hemisphere for the first time in Brazil (2) and Argentina (1). Reports of gladiolus rust in several central Mexican states from 2004 to 2005 (3; http://www.pestalert.org/espanol/oprDetail.cfm?oprID=138 ) and interceptions at Mexican border stations and in Brazilian imports in 2005 at the port of Miami, FL collectively raised the alert level in the United States to high. In April 2006, the Hawaii Department of Agriculture notified the USDA of rust-infected gladiolus in a cut-flower shipment that was traced back to a 1,400-acre (565 ha) farm in Manatee County, FL. Inspection at the farm yielded samples that were quickly confirmed as U. transversalis by FDACS-DPI and USDA plant pathologists. The disease was identified in eight residential gardens near the commercial find and in another 700-acre (285 ha) farm in remote Hendry County, 100 miles to the southeast. In May 2006, gladiolus rust was detected in residential and commercial gladiolus in San Diego County, CA (see companion publication). On the advice of a USDA-assembled panel of experts, strict rust management guidelines and fallow host-free periods were implemented with the ultimate goal of eradication. Subsequent summer, fall, and now winter surveys in the infested commercial and residential areas have uncovered diminishing amounts of rust, with last traces detected on 9 September 2006. Commercial planting resumed at both farms in late summer, and crops remained rust free under weekly inspection until 15 February 2007 in Manatee County and 29 March 2007 in Hendry County. To insure a rust-free product, cut flowers are carefully inspected and foliage stripped at the packinghouse. Eradication will be attempted once more with a fallow host-free period before the 2007 season. U. transversalis is an autoecious rust that mainly infects Gladiolus spp., but has been known to infect other members of the Iridaceae: Anomatheca, Crocosmia, Melasphaerula, Tritonia, and Watsonia. Amphigenous uredinia form in transverse lines across gladiolus foliage and also on flower spikes under heavy disease pressure. The isolate present in Florida fits the literature description of U. transversalis in every respect (uredinia 0.5 to 1.5 mm in diameter, subglobose to ellipsoid verruculose yellow-amber urediniospores, 15 to 28 × 14 to 20 μm with wall 1.5 to 2.5 μm thick; telia also amphigenous, 0.5 to 1.3 μm in diameter, dark brown-black, subglobose to pyriform smooth amber teliospores, 20 to 30 × 15 to 20 μm with wall 1.5 to 2.0 μm thick, 4 to 6 μm thick at apex, pale brown to hyaline pedicel 30 to 40 μm long, yellow-brown paraphyses in pustule) ( http://nt.ars-grin.gov/fungaldatabases/new_allView.cfm?whichone=all&thisName=Uro myces%20transversalis&organismtype=Fungus ). Urediniospores initiated typical foliar lesions on transplanted gladiolus samples kept in the FDACS-DPI quarantine greenhouse during the diagnostic process. References: (1) J. R. Hernandez and J. F. Hennen. Sida 20:313, 2002. (2) G. P. B. Pitta et al. Biologica 47:323, 1981. (3) G. Rodriguez-Alvarado et al. Plant Dis. 90:687, 2006. (4) J. A. Stevenson. Page 82 in: Foreign Plant Diseases. USDA Fed. Hortic. Board Bureau Plant Ind. Government Printing Office, Washington DC, 1926.

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