Incidence and severity of Leifsonia xyli subsp. xyli infection of sugarcane in Sao Paulo State, Brazil.

摘要

Sugarcane covers 8.53 million hectares with production of 596.63 million tonnes in Brazil. Despite its importance, little information is available on ratoon stunt (RSD), caused by Leifsonia xyli subsp xyli (Lxx). Our objective was to examine the incidence and severity of Lxx among sugarcane cultivars in 2009, 2010 and 2011. Sap from 100 stalks from each field was sent for a routine RSD analyses that allowed examination of Lxx incidence. The presence of bacterium was checked by dot blot enzyme immunoassay to detect its presence and relative concentration. Analyses of 187 fields from 35 cultivars in 2009, 166 fields from 33 cultivars in 2010 and 221 fields from 30 cultivars in 2011 found Lxx incidence of 23.6% of fields of 23 cultivars in 2009, 27.1% of fields of 15 cultivars in 2010 and 25.8% of fields of 15 cultivars in 2011. RB867515, the major cultivar in Sao Paulo, had within-field incidence of up to 70% in 2009, 48% in 2010 and 88% in 2011. Highest incidence and populations of Lxx infection were found for cvs RB867515, RB855453, SP81-3250, RB855536 and RB92579, demonstrating their susceptibility to RSD.