Effect of leaf scald disease on a major Brazilian sugarcane cultivar and cultivar reaction to Xanthomonas albilineans

Abstract

Background The lack of information on the damage caused by leaf scald disease (LSD) hinders the sugarcane industry to adopt measures to control it. One distinct feature of LSD is its latent stage where diseased canes are symptomless enabling nurseries be formed from asymptomatic materials. The chance to find two commercial sugarcane fields of RB966928, with similar characteristics grown side by side, but contrasting in phytosanitary status, gave a rare opportunity to examine the importance of LSD in Brazil scientifically. Therefore, the objectives of this work were to quantify the damage caused by LSD in a real-world condition in the most important Brazilian cultivar as well as to examine reaction of different cultivars to the disease. Results Data showed visual incidence varying from 21 to 72% whereas lab-based incidence ranged from 50 to 72%, a comparison between the two fields showed a significant difference in percentage of stalk death (above 42%), stalk weight (above 14%) and stool weight loss (above 54%). Five out of ten cultivars were classified as susceptible or moderately susceptible, where RB966928 and RB92579 were the most susceptible. Clean seedcane proved to be an effective means to control LSD since the field employed as gold standard was originated from different nursery and remained symptomless throughout the crop season. Conclusion Leaf scald disease caused severe damage in a commercial sugarcane field and lab-based diagnostic of seedcanes is paramount to control the disease.