Uredinial Lesions Research Articles

First report of orange rust caused by Puccinia kuehnii on sugarcane in South Africa.

In February 2022, rust-like lesions were observed on commercial sugarcane cultivar N76 in the North Coast area of KwaZulu-Natal, South Africa (29°23'45.95"S; 31°10'3.91"E). Moderate to severe leaf symptoms were present throughout the 0.2 ha field that was planted in August 2021. The symptoms differed from those of the two sugarcane rusts commonly observed in South Africa, namely, brown rust (Puccinia melanocephala H. & P. Sydow) and tawny rust (Macruropyxis fulva L.A. Martin, S.A. McFarl. and L.A. Castl.) (Martin et al., 2017). Similar symptoms were subsequently observed on several additional cultivars in other regions of the industry. Up to five leaves were collected from each contaminated field and examined under a dissecting microscope. Uredinial lesions were orange-brown, cinnamon-brown to red-brown in colour and were 0.5 to 5 × 0.2 to 0.5 mm. Uredinia within the lesions were 300 to 820 × 28 to 40 μm, mainly hypophyllous although epiphyllous uredinia were occasionally observed on severely infected leaves. Uredinia were ellipsoid to fusiform in shape. Urediniospores were transferred to microscope slides and examined at 400x magnification. The urediniospores were morphologically similar to Puccinia kuehnii E. J. Butler, causal agent of sugarcane orange rust (Glynn et al., 2010). They were orange to cinnamon-brown in colour, mostly obovoid to pyriform in shape and moderately echinulate. They were variable in size (25 to 55 × 22 to 27 μm), most with obvious apical thickening of up to 10 μm. Inconspicuous paraphyses were occasionally present but no telia or teliospores were observed. Identity of the pathogen was confirmed using primers Pk2-F and Pk1-R, targeting the internal transcribed spacer (ITS1-5.8S-ITS2) region (Glynn et al., 2010). The 384-bp sequence (GenBank Accession no: ON329808) matched 100% with P. kuehnii submissions on Genbank and was distinct from those of P. melanocephala and M. fulva. Rust symptoms observed on cultivar Co301 in South Africa from 1941 were previously reported to be caused by P. kuehnii (Gorter, 1977; Crous et al., 2000). However, the pathogen was later correctly identified as P. melanocephala (Bailey, 1979). This is therefore the first report of P. kuehnii infecting sugarcane in South Africa, after being detected periodically on a spore trap located in Komatipoort, Mpumalanga (25°33'2.83"S 31°57'22.19"E) since 2016. An Emergency Response Plan, developed in anticipation of an orange rust incursion in South Africa, guided the initial response of the industry. This included the application of a fungicide (a.i. azoxystrobin / cyproconazole) pre-emptively registered for orange rust on sugarcane in South Africa in infected fields, notification of key contacts in southern Africa, and industry-wide surveys to determine prevalence and provide an indication of varietal susceptibility. Long term management will include screening for varietal resistance and the registration of additional fungicides against the disease. Research on the conditions favouring infection will allow the inclusion of orange rust in the local sugarcane rust forecasting model, while trials to assess the effect on yield will provide an indication of the impact of the disease on production.

First Report of Puccinia kuehnii Causing Orange Rust of Sugarcane in Texas, U.S.A.

In April 2017, uredinial lesions typical of orange rust caused by Puccinia kuehnii E.J. Butler were observed on the experimental sugarcane clone HoCP 14-801 (a complex hybrid of Saccharum L. spp.) in a cultivar trial in Hidalgo County, Texas. Additional observations were made in cultivar trials at three other sites in Hidalgo, Cameron, and Willacy Counties during the following 5 months of 2017. Orange rust symptoms were observed on 12 experimental clones and one commercial check cultivar, CP 89-2143, at one or more of the three trial locations. Cultivar trials were embedded in commercial fields. Uredinial lesions were orange and linear, measuring 650 to 850 × 26 to 32 µm. The orange to light cinnamon brown urediniospores were mostly obovoid or pyriform and variable in size (30 to 60 × 25 to 30 µm). Walls were 1 to 2 µm thick on the sides with a pronounced apical thickening of 5 µm or more and were echinulate with evenly distributed spines 2 to 4.5 µm apart. These morphology features were consistent with those described by Ryan and Egan (1989) and others for Puccinia kuehnii. Telia and teliospores were not observed. Leaf samples containing rust lesions were collected from cultivar CP 89-2143 and experimental clones HoCP 14-801, HoCP 14-874, and CP 11-2013. Identification of the species causing the orange rust lesions was verified by PCR assays conducted independently in two laboratories (Sugarcane Research Unit, ARS, USDA, Houma, LA, and Soybean/Maize Germplasm, Pathology, and Genetics Research Unit, USDA-ARS, Urbana, IL). Primers PkPmF and PkPmR were used that amplify fragments of 606 bp from P. kuehnii and 585 bp from P. melanocephala, the causal agent of brown rust of sugarcane (Glynn et al. 2010). Only the 606-bp fragment corresponding to P. kuehnii was amplified from each sample. No fragments were amplified when a PCR analysis with primers AR-F2 and AR-R1, which amplify Macruropyxis fulva, the pathogen causing tawny rust on sugarcane (Martin et al. 2017), was conducted on the samples. Sequences of the fragments were identical to each other, and a BLAST search of GenBank revealed 100% identity to previously reported isolates of P. kuehnii including an isolate from Florida, U.S.A. (GenBank accession no. EU176008). Sequences from P. kuehnii infecting CP 11-2013 (GenBank accession no. MN547621) and HoCP 14-874 (GenBank accession no. MN547622) were submitted to GenBank with voucher collection maintained at the USDA, ARS, Sugarcane Research Unit in Houma, LA. This is the first report of orange rust in the sugarcane production area of Texas. In 2018, approximately 50% of the sugarcane production area in Texas was planted with cultivar CP 89-2143. Although this cultivar was known to be susceptible to orange rust, it was introduced and expanded prior to the observation of orange rust in the industry. Orange rust was observed in commercial fields of cultivar CP 89-2143; however, disease severity was less than that observed in some experimental clones. In Florida, overall losses from orange rust have been estimated to be 10% with reductions as high as 43% in a highly susceptible cultivar (Rott et al. 2014). As researchers attempt to identify new sugarcane cultivars that are adapted to the Texas production area and provide diversity among the cultivars, susceptibility to orange rust must be considered.

First Report of Orange Rust of Sugarcane Caused by Puccinia kuehnii in Guyana

In September 2012, orange uredinial lesions (0.3 mm to 1.2 mm in length x 0.1 mm to 0.3 mm in width; mean of 0.6 mm ± 0.16 mm in length x 0.2 mm ± 0.01 mm in width) surrounded by dark, reddish-brown necrotic tissue and running parallel to the leaf venation were observed on leaves of a major commercial sugarcane (Saccharum spp. L. hybrid) cultivar - DB7869, grown on an estate, in east Berbice-Corentyne, Guyana. Golden yellow to orange coloured obovoid urediniospores (27.5 µm to 60.0 µm in length x 17.5 µm to 37.5 µm in width; mean of 38.0 µm ± 7.82 µm in length x 24.0 μm ± 3.31 µm in width) with distinct apical wall thickenings were visible using both light and scanning electron microscopy based on a random sample of 30 urediniospores. These features were characteristic of Puccinia kuehnii (W. Kruger) E.J. Butler, the causal agent of orange rust of sugarcane (Virtudazo et al. 2001). Isolated DNA from symptomatic dried leaf material was amplified using P. kuehnii species specific primers (Pk1-F/Pk1-R) targe...

First Report of Rust Caused by Pucciniastrum boehmeriae on Māmaki (Pipturus albidus) in Hawaii

Pipturus albidus (Hook. & Arn.) A. Gray or māmaki is a flowering plant species in the Urticaceae (nettles) endemic to the Hawaiian Islands. Māmaki is a forest and agricultural commodity, as well as a traditional medicinal and fiber crop. In August 2013, leaf rust was observed in Kuristown, Hawaii, on 15 māmaki plants. Infected leaves had vein-delimited chlorotic spots on the adaxial surface and yellow to orange uredinia on the abaxial surface. Uredinia were scattered, minute, pulverulent, subepidermal, and dome-shaped with a central pore, consistent with Pucciniastrum. Urediniospores were 16 to 23 × 10 to 14 μm, echinulate, ellipsoid to pyriform, walls hyaline, 0.5 μm thick, contents pale yellow to bright yellow. No teliospores were observed. A voucher specimen was deposited in the U.S. National Fungus Collections (BPI 892695). The only species of Pucciniastrum previously known on Pipturus, Pucciniastrum pipturi Syd. [syn. Uredo pipturi (Syd.) Hirats. f.], has larger urediniospores, 26.5 to 40.0 × 19.5 to 27.5 μm, and is currently reported from Japan and the Philippines (3). The pathogen was identified as Pucciniastrum boehmeriae (Dietel) Syd. & P. Syd., which infects Boehmeria Jacq., also in the Urticaceae, and has urediniospores that are 18 to 27 × 13 to 18 μm and similar in shape (2). DNA was extracted from uredinial lesions and the nuclear ribosomal internal transcribed spacer (ITS2) region and the 5' end of large subunit (28S) rDNA were amplified and sequenced following the protocol of Aime (1). The resulting fragment (GenBank Accession No. KF711854) was 100% identical to authenticated and vouchered P. boehmeriae ITS2/28S rDNA sequences (AB221449 to AB221451 and AB221391 to AB221393) (4). Sequences from P. pipturi are not available for comparison, but host family, molecular, and morphological data support the identification of the rust as P. boehmeriae, which is found throughout eastern Asia. To our knowledge, this is the first report of P. boehmeriae on māmaki and the first report in Hawaii on any host. Plant health professionals and regulatory officials can utilize this information to establish survey methods and implement appropriate management practices for this rust disease.

First Report of Orange Rust of Sugarcane Caused by Puccinia kuehnii in Colombia.

Symptoms of sugarcane orange rust were first observed in July 2010 on sugarcane (interspecific hybrid of Saccharum L. species) cv. CC 01-1884 planted in the La Cabaña Sugar Mill, Puerto Tejada, Colombia. Morphological features of uredinial lesions and urediniospores inspected with an optical microscope and scanning electron microscopy were distinct from common rust of sugarcane caused by Puccinia melanocephala Syd. & P. Syd., revealing spores identical morphologically to those described for the fungus P. kuehnii (Kruger) E. Butler, causal agent of sugarcane orange rust (1,3). Uredinial lesions were orange and distinctly lighter in color than pustules of P. melanocephala. Urediniospores were orange to light cinnamon brown, mostly ovoid to pyriform, variable in size (27.3 to 39.2 × 16.7 to 21.2 μm), with pronounced apical wall and moderately echinulate with spines evenly distributed. Paraphyses, telia, and teliospores were not observed. Species-specific PCR primers designed from the internal transcribed spacer (ITS)1, ITS2, and 5.8S rDNA regions of P. melanocephala and P. kuehnii were used to differentiate the two species (2). The primers Pm1-F and Pm1-R amplified a 480-bp product from P. melanocepahala DNA in leaf samples with symptoms of common rust. By contrast, the primers Pk1-F and Pk1-R generated a 527-bp product from presumed P. kuehnii DNA in leaf samples with signs of orange rust, confirming the identity as P. kuehnii. The Centro de Investigación de la Caña de Azúcar de Colombia (Cenicaña) started a survey of different cultivars in nurseries and experimental and commercial fields in the Cauca River Valley and collected leaf samples for additional analyses. Experimental cvs. CC 01-1884, CC 01-1866, and CC 01-1305 were found to be highly susceptible to orange rust and were eliminated from regional trials, whereas commercial cvs. CC 85-92 and CC 84-75, the most widely grown cultivars, were resistant. With the discovery of orange rust of sugarcane in Colombia, Cenicaña has incorporated orange rust resistance in the selection and development of new cultivars. To our knowledge, this is the first report of P. kuehnii on sugarcane in Colombia. Orange rust has also been reported from the United States, Cuba, Mexico, Guatemala, Nicaragua, El Salvador, Costa Rica, Panama, Ecuador, and Brazil.

First Report of Leaf Rust of Blueberry Caused by Thekopsora minima in Mexico.

Blueberry (Vaccinium corymbosum L.) is becoming an important crop in the states of Jalisco and Michoacan in Mexico. Leaf rust, a disease causing extensive defoliation on plants with severe infections, was observed in the autumn of 2007 and it has become one of the most significant diseases of blueberry in these states. Symptoms on the upper surfaces of leaves appear as small, yellow spots that later turn necrotic as they enlarge and coalesce and eventually cover large areas of individual leaves. On the undersides of leaves, small flecks surrounded by small water-soaked halos appear, turn yellow, and produce powdery sori that are uredinia with urediniospores. Uredinia were hypophyllous, scattered to gregarious and at times superficially appearing confluent, up to about 300 μm in diameter, dome shaped and peridium hemispherical in cross section, orangish, becoming pulverulent, lacking obviously enlarged, well-differentiated ostiolar cells. Urediniospores were subglobose, obovate, oblong or ellipsoid, 17.6 to 27.2 × 12.8 to 17.6 μm, with hyaline, echinulate walls that are 1.2 to 1.8 μm thick, and with yellow-to-hyaline contents. Telia were not observed. On the basis of uredinial morphology (3,4), the rust was identified as Thekopsora minima P. Syd. & Syd. To distinguish this rust from other rust species causing disease on Vaccinium (2,3), a 1,414-bp region consisting of ITS2 and the 5' end of the 28S was amplified with primers Rust2inv/LR6 from uredinial lesions on infected leaves of V. corymbosum 'Biloxi' and sequenced (BPI 880580; GenBank Accession No. HM439777) (1). Results of a BLAST search of GenBank found 100% (1,414 of 1,414) identity to T. minima (GenBank Accession No. GU355675) from South Africa (3). Pathogenicity tests were completed as follows: (i) during the autumn of 2009, rusted leaves of cvs. Biloxi and Sharpblue were collected from the field; (ii) mature leaves from healthy plants of both blueberry cultivars were surface disinfested with 1% sodium hypochlorite for 2 min and rinsed with sterile distilled water; (iii) fresh urediniospores from rusted leaves were brushed directly onto the undersides of disinfested detached leaves; (iv) to avoid drying, wet cotton balls were placed on the petioles of inoculated leaves that were subsequently placed in resealable plastic bags; and (v) leaves were then incubated in a growth chamber at 22°C with a 12-h photoperiod. For each cultivar, 20 leaves were inoculated and five uninoculated leaves were included as controls and the test was repeated once. Yellow uredinia were observed 13 and 10 days after inoculation in cvs. Biloxi and Sharpblue, respectively. Leaf symptoms and uredinial characters were the same as observed previously in the field. To our knowledge, this is the first report of T. minima in Mexico. This report is significant for growers who need a diagnosis to control the disease and for breeders and plant pathologists who should consider developing more resistant cultivars.

First Report of Orange Rust of Sugarcane Caused by Puccinia kuehnii in Ivory Coast and Cameroon

Orange rust of sugarcane caused by Puccinia kuehnii was detected in Florida in 2007 (1). It was hypothesized that the pathogen originated from Africa because brown rust of sugarcane (synonym common rust) was introduced to the Western Hemisphere from Africa (3). Requests for rust-infected sugarcane samples were made to several western and central African countries to investigate if orange rust of sugarcane was present but as yet undetected. Orange rust had not previously been reported from western or central Africa. At Zuénoula, Ivory Coast in July 2009, symptoms of sugarcane rust were observed on cvs. SP 71-6180 and Co 997 and appeared distinct to those of brown rust of sugarcane. A year later (May 2010), rust-infected specimens of SP 71-6180 and Co 997 from the same location and also from Borotou in Ivory Coast were sent to the USDA-ARS Systematic Mycology and Microbiology Laboratory in Beltsville, MD for identification. Also in May 2010, sugarcane rust was observed at Mbandjock and Nkoteng in Cameroon on cvs. D 88172, FR 87482, and RB 72-454 and on breeding clones RCmr 08/319 and RCmr 08/1121. All specimens had orange uredinial lesions that ranged from 0.6 to 6.5 mm × 200 to 300 μm and were ellipsoidal to elongate. Urediniospores were consistent with P. kuehnii E.J. Butler observed on specimens from Florida (1). DNA isolated from all samples was successfully amplified with P. kuehnii specific primers targeting ITS1 of rDNA (2). The nuclear large subunit region of rDNA of the rust specimens from Ivory Coast (BPI 881015-881017, GenBank Accession No. HQ666888) and Cameroon (BPI 881010-881014, GenBank Accession Nos. HQ666889-HQ666891) were sequenced. DNA sequences for all were identical to sequences of P. kuehnii and distinct from known sequences of P. melanocephala available in GenBank. To our knowledge, this is the first confirmed report of orange rust of sugarcane in western and central Africa. There is evidence that brown rust of sugarcane was introduced to the Western Hemisphere from this region of Africa (3) making it also the likely source of introduction of orange rust. Further experimentation is required to confirm this hypothesis.

Definitive identification of orange rust of sugarcane caused by Puccinia kuehnii in Cuba

In November 2008, leaf lesions, pale yellow to yellow-orange, sometimes coalescing in large necrotic areas, were observed on hybrid sugarcane clones (Saccharum spp.) CSG 86-504, CSG 24-92, CSG 204-92 and CC 87-409 at the Sugarcane Research Institute (INICA) Station in Villa Clara province, in central Cuba. Specimens were submitted to the Central Plant Quarantine Laboratory for identification. The observed morphological features were consistent with those described for Puccinia kuehnii (Virtudazo et al., 2001; Comstock et al., 2008). Uredinial lesions, variable in size (3–4 mm in length), were generally light brown in colour, but occasionally yellow-orange to cinnamon brown. Hypophyllous uredinia were ellipsoidal to fusiform in shape, distinctly lighter and less uniformly distributed than for P. melanocephala. Urediniospores were mostly obovoid to pyriform, almost ellipsoidal in shape, variable in size, 27·5–55·0 (41·9) × 17·5–37·5 (26·0) μm, echinulate with evenly distributed spines. Walls (orange to light cinnamon brown in colour) were 1–2·5 μm thick, often with a pronounced apical thickening, 3–7 μm (mode 5 μm). Four to five equatorial pores were present. In contrast to P. melanocephala, paraphyses were not visible in stereoscopic views of the uredinia and were absent in most specimens. Telia and teliospores were not observed. Total DNA isolation from symptom-bearing leaves with uredinia was performed according to Lin et al. (2001). A real time PCR was conducted using the SYBR green technique with primers synthesized from exact sequences of ITS1, 5·8S, and ITS2 of the large subunit rDNA region reported in GenBank Accessions EU164549 and EU176009 (Comstock et al., 2008). Results confirmed the identification as P. kuehnii. Previous reports of P. kuehnii in Cuba (Commonwealth Mycological Institute, 1969) were based on misidentifications of P. melanocephala. To the authors’ knowledge, P. kuehnii has not been reported by any diagnostic laboratory in Cuba in the last 30 years. In addition, Cuba was not included in the latest P. kuehnii distribution map (CAB International, 2007). Therefore, this is the first confirmed report of the presence of P. kuehnii in Cuba. The disease has since been found in different localities in the central and eastern regions of Cuba, without any reported economic losses to date.

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

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.

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

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.

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.

First Report of Uromyces transversalis, Causal Agent of Gladiolus Rust, in San Diego County, California.

In May 2006, signs and symptoms of a rust disease were observed on hybrid gladiolus plants in a home garden located in the city of San Diego, CA. Uredinial lesions were bright orange, variable in shape from globose to oval to transversely elongate, and measured 28 to 652 × 36 to 994 μm. Urediniospores measured 16 to 26 × 16 to 23 μm and had hyaline walls that were 2 μm thick and finely echinulate with recurved spines. Some uredinial lesions located primarily at the base of the leaves were surrounded by dark, irregular lesions (telia) by the epidermis. Telia contained nonseptate, light-to-chestnut brown teliospores that measured 20 to 30 × 13 to 20 μm with an apical thickening measuring 2 to 5 μm. Teliospore pedicels measured 3 to 33 × 2 to 5 μm. Groups of teliospores were separated into locules by upright, pale brown paraphyses. The rust was identified as Uromyces transversalis, the cause of gladiolus rust and a quarantine pest for the United States. An intensive 23 square mile survey was initiated and resulted in the detection of infected plants at one nearby residence 200 feet away, in a commercial nursery six miles east of the initial site of detection, and at a residence across the street from the infected nursery. Plants in the nursery were grown outdoors in three blocks, in which the disease incidences were 20, 80, and 100% with varying levels of severity. Telia were also found at this location. The nursery grows gladiolus flowers for sale at local farmer markets, sometimes supplemented by additional cut gladiolus from Mexico. U. transversalis is known to occur in Mexico (2). This rust is under eradication at all four sites. Gladiolus rust was reported in Florida in April 2006. To our knowledge, this is the first confirmed report of Gladiolus rust in California.