Submitted to: International Society of Sugar Cane Technologists Pathology Workshop
Publication Type: Abstract Only
Publication Acceptance Date: February 14, 2011
Publication Date: N/A
Technical Abstract: During the past 25 years in Louisiana, symptoms of red stripe caused by Acidovirax avenae subsp. avenae on sugarcane were limited to the red stripe form of the disease with no apparent yield loss. However, the more severe top rot symptom of the disease was observed in commercial sugarcane fields in 2010, most frequently in cultivar HoCP 00-950. Two commercial fields of cultivar HoCP 00-950, a 0.45 ha plant cane (PC) field and a 1.83 ha first ratoon (FR) field, were subdivided into 113 and 84 plots, respectively. In the PC field, tonnes cane/hectare, kg sugar/tonne, and kg sugar/hectare were reduced in plots with >20% of stalks with top rot symptoms by 5%, 10%, and 14%, respectively, when compared to plots with lower disease incidence; and 4%, 6%, and 9%, respectively, in the FR field. In another test dealing with nitrogen rates with HoCP 00-50, a disease incidence, nitrogen fertility rate, and soil texture interaction was noted. Incidence was higher among plots in heavy clay soils verses lighter, more silty soils; increased nitrogen in the heavy clay soil increased disease incidence. In the lighter soil, disease incidence was higher in plots with added nitrogen, but did not differ among the different nitrogen rates. To determine the effect of using seed cane from fields infected with red stripe and expressing top rot symptoms, plots were planted with randomly cut stalks included symptomatic (striped or top rot symptoms) and non-symptomatic stalks. Shoot counts were reduced by 15% compared to the plots planted with symptomless stalks only. Use of stalks with top rot symptoms resulted in a 60% reduction of shoots per plot, while shoot counts in plots planted with stalks showing only leaf striping symptoms did not differ from plots planted with stalks showing no symptoms.