Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: March 15, 2011
Publication Date: June 1, 2011
Citation: Grisham, M.P., Johnson, R.M. 2011. Top rot form of red stripe caused by Acidovirax avenae subsp. avenae in Louisiana sugarcane. Phytopathology. 101(6):564. Technical Abstract: Red stripe of sugarcane caused by Acidovirax avenae subsp. avenae consists of two forms – leaf stripe and top rot. Symptoms of red stripe in Louisiana over the past 25 years have been limited to the leaf stripe form which causes no apparent yield loss. During 2010, the more severe top rot form was observed in several commercial sugarcane fields. Both forms were found, either separately or together. Two fields of cultivar HoCP 00-950, one plant-cane (PC) crop and one first-ratoon (FR) crop, affected by top rot were subdivided into 113 and 84 plots, respectively. In the PC test, plots with >20% affected stalks averaged a 5%, 10%, and 14% loss of tonnes cane/hectare, kg sugar/tonne, and kg sugar/hectare, respectively. In the FR test, the infection level was lower and a 10% loss threshold was utilized, resulting in a 1%, 4% and 4% loss of tonnes cane/hectare, kg sugar/tonne, and kg sugar/hectare, respectively. A disease incidence, nitrogen fertility rate, and soil texture interaction was noted in plots of nitrogen fertility rate experiment. Incidence was higher among plots in heavy clay soils verses lighter, more silty soils. Disease incidence increased with increasing rates of added nitrogen in the heavy clay soil compared to the control, no nitrogen added plots. In the lighter soil, disease incidence was higher among treatments with added nitrogen compared to the control, but incidence did not differ among the different rates of added nitrogen fertilizer.