Relationship between resistance to Clavibacter xyli subsp. xyli colonization in sugarcane and spread of ratoon stunting disease in the field.
The spread of ratoon stunting disease (RSD) of sugarcane resulting from hand-cutting was monitored in plots of 6 different cultivars that varied in RSD resistance in Florida, USA. Cultivar resistance influenced disease spread. Spread was low among plants of an RSD-resistant cultivar that had low numbers of C. x. subsp. xyli-colonized vascular bundles (cvb) (determined in 1-cm-diam. core sample of stalk tissue). The rate of spread and incidence were highest in the most susceptible cultivar which had c. 20 cvb/core sample. Disease spread followed the direction of hand harvest within rows form infected source plants (inoculated) to test plants (uninoculated). The incidence of RSD in test plants increased with the number of ratoon crops harvested.