Impact of sugarcane streak mosaic virus (SCSMV) on cane and sugar yields of some commercial varieties in Zuénoula, Côte d'Ivoire

Sugarcane streak mosaic virus (SCSMV) is an emerging virus in Côte d'Ivoire. First observed less than 10 years ago, it is now present in all sugar production areas, with a high prevalence in some sites and rapid increase in others. The aim of this study was to assess the impact of SCSMV on cane and sugar yields of six commercial sugarcane varieties in the Zuénoula integrated agricultural unit. Cuttings with four different levels of disease severity were planted and monitored. Agronomic parameters and technological parameters were determined. The level of SCSMV severity on cuttings had a significant effect on all agronomic parameters. Overall, germination rate, tillering, plant height, stem diameter, number of internodes and cane yieldat harvest were significantly reduced by 15 to 29% for plants deriving from cuttings at the highest severity level. SCSMV had no significant effect on fiber content in cane, sucrose content in cane, cane juice sucrose purity and extractable sugar content. Depending on varieties, cane yield losses and extractable sugar yield losses ranged from 13 to 34% and 15 to 42% respectively. The relationships between yield losses and severity levels in cuttings were successfully modelled with the three-parameter Gompertz function for all varieties. Considering the deleterous effect of SCSMV on cane and sugar yields, the planting of healthy cuttings is the key prophylactic mesure to mitigate virus impact.