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Disease Note.

First Report of Leaf Scald, Caused by Xanthomonas albilineans, of Sugarcane in Texas. T. Isakeit, Texas A&M University Agricultural Research and Extension Center, 2401 E. Highway 83, Weslaco 78596. J. E. Irvine, Texas A&M University Agricultural Research and Extension Center, 2401 E. Highway 83, Weslaco 78596. Plant Dis. 79:860. Accepted for publication 2 June 1995. Copyright 1995 The American Phytopathological Society. DOI: 10.1094/PD-79-0860A.

In May of 1993, white pencil-line streaks and chlorosis were evident on leaves of sugarcane (Saccharum interspecific hybrid LCP82-89) in a variety trial near Runn, Texas. Isolations were made from tissue showing these symptoms on a medium selective for Xanthomonas albilineans, as described previously (1). Developing colonies that were typical of X. albilineans were purified and tested further. Identity was determined by physiological tests, fatty acid profiles (0.61-0.75 similarity index using the Microbial Identification System, Texas Plant Disease Diagnostic Laboratory, College Station), and with a dot immunobinding assay using a specific antiserum provided by V. Moraes, Copersucar, Piracicaba, SP, Brazil. Over the next 2 years, isolations of X. albilineans were made from plants with leaf scald symptoms of 13 Texas-Canal Point (TCP) clones in variety trials in four other locations in Hidalgo County. LCP82-89 and five of the 13 TCP clones (88-3448, 88-3480, 89-3505, 90-3523, and 92-3582) were imported from Louisiana as stalks, which may have had latent infections. However, eight other clones (88-4002, 88-4013, 89-4041, 89-4042, 89-4057, 89-4065, 89-4077, and 90-4114) were derived from true seed germinated in Texas, suggesting that they were infected locally. Seventeen isolates of X. albilineans from different varieties and locations were tested by P. Rott (CIRAD-CA, Montpellier, France) and found to be serovar 1, which is common in Florida and Louisiana. In March, 1995, the disease was found in four stools in a 25-ha commercial planting of CP71-124O near Runn. The source of inoculum in this field is not known.

Reference: (I) J. W. Hoy and M. P. Grisham. Plant Dis. 78:1083, 1994.