Resistance status of sugarcane grown in Nigeria to ratoon stunting disease

Abstract

Sugarcane is an important widely cultivated crop in Nigeria. Leifsonia xyli subsp. xyli, causing ratoon stunting (RSD), is the most economically damaging bacterial diseases of sugarcane globally. Presence of RSD was not confirmed in Nigeria; thus, the reactions of sugarcane to RSD in Nigeria are unknown. Thus, the study evaluated sugarcane germplasm grown in major producing states for resistance to RSD. L. xyli subsp. xyli inoculated and uninoculated sugarcane varieties comprising susceptible (CP72-1210), moderately resistant (CP80-1743), most commonly grown (Co957, Co997, SP71-6180, Co62175, chewing cane, B47419, Co6806) and locally bred (NCS001, NCS002, NCS003, NCS005, NCS006, NCS007, NCS008, ILS001 and ILS002) were evaluated in the screenhouse for both plant and ratoon crops. Resistance of the varieties to L. xyli subsp. xyli was determined using numbers of colonized vascular bundles (CVB) (highly resistant (HR) ≤5 % to highly susceptible (HS) ≥65 %) and cane yield loss (HR ≤5 % to HS ≥50 %). Varieties ILS002, NCS001, NCS007, SP71-6180 (≤28.2 % CVB; ≤10.0 % yield loss) and Co957 (≤10.0 % yield loss) were moderately resistant. Yield loss for plant crop and ratoon crop ranged from 2.6–41.7 to 5.4–42.1 %, respectively, and were significantly correlated (r = 0.94). In plant crop and ratoon crop, CVB significantly correlated with yield loss (r = 0.94, 0.88, respectively).