Location: Sugarcane Field StationTitle: First Report of Orange Rust of Sugarcane caused by Puccinia kuehnii in Ecuador Author
Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/10/2014
Publication Date: 6/4/2014
Citation: Garcés, F.F., Fiallos, F.F., Silva, E., Martinez, F., Aime, M.C., Comstock, J.C., Glynn, N.C., Castlebury, L.A. 2014. First Report of Orange Rust of Sugarcane caused by Puccinia kuehnii in Ecuador. Plant Disease. 89:842. Interpretive Summary:
Technical Abstract: Orange rust, Puccinia kuehnii (W. Krüger) E.J. Butler, is an important disease of sugarcane (complex hybrid of Saccharum L. species) that causes yield losses, and impacts breeding programs. Initially confined to the Asia-Oceania region (5), P. kuehnii was reported in Florida in June 2007 (2) and later in Central and South America. Orange rust pustules were observed in August 5th 2011 in commercial fields of the cv. SP79-2233 and sugarcane clones of the CINCAE breeding program (EC06-351, EC06-340 and EC01-744) located in the Ecuadorian pacific coast of South America. Under light microscope typical urediniospores were pale in color with thickened apices and irregularly echinulate. Uredinia lacked paraphyses as those reported in P. kuehnii (3, 5). After DNA extraction, qPCR amplification (4), and 28s large ribosomal subunit DNA sequencing (1), positive detection and quantification, and 100% sequence identity (932/932 base pairs) were observed. Low levels of disease incidence and severity at the CINCAE breeding program and sugarcane germoplasm have been observed. Recently released and commercial varieties have not yet shown symptoms of infections. However, a survey conducted in 2011 and 2012 showed an increase of disease severity from 3% to 28% in the introduced susceptible cv. SP79-2233. Symptoms of infections were evident during stalk growth to maturity (from 7 to 12 months), especially at the beginning of the harvesting season. This is the first report of presence, distribution and disease spread of the sugarcane orange rust P. kuehnii in Ecuador.