Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/3/2009
Publication Date: 12/22/2009
Citation: Flores, C., Loyo, R., Ojeda, A., Rangel, C.A., Ceron, F., Marquez, W., Guerra-Moreno, A.S., Hernandez, H.M., Gonzalez, R.E., Castlebury, L.A., Dixon, L.J., Glynn, N.C., Comstock, J.C., Flynn, J., Amador, J. 2009. First Report of Orange Rust of Sugarcane Caused by Puccinia kuehnii in Mexico, El Salvador and Panama. Plant Dis. 93:1347 Interpretive Summary: Sugarcane orange rust was detected Mexico, El Salvador and Panama and increases the number of Western Hemisphere countries to seven since it was first confirmation in Florida in June 2007. Symptoms of the disease and morphological and molecular confirmation were consistent to previous identifications and samples from Southeast Asia where the disease has been historically present. Orange rust continues to cause an economic threat to susceptible sugarcane cultivars ‘CP 80-1743’ in Florida and ‘CP 72-2086’ Central America. Due to the windblown dispersal of spores of the Puccinia kuehnii, the causal agent of orange rust, it is highly likely that the disease will spread further areas where sugarcane is grown.
Technical Abstract: Symptoms of sugarcane orange rust were observed on July 17, 2008 in sugarcane varieties, 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 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 cultivar 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 Maryland for identification. Panamanian samples were collected similarly and analyzed at the CALESA Biotechnology Lab. 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. 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 from Mexico (BPI 878930, 879139, and 879140; GenBank Accessions GO283006, GO283004, and GO283005, respectively) from Mexico and cv. CP 72-2086 from three locations in El Salvador (BPI 879135, 879136, and 879137; GenBank Accessions 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 GO281584) confirmed the identification of P. kuehnii in Panama. This is the first report of P. kuehnii causing the 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.