Comparative efficacy of different inoculation methods in screening sugarcane varieties for resistance to Fusarium sacchari

Fusarium sacchari, the causal organism of sugarcane wilt, is a major constraint to sugarcane yield in India and other countries. Unlike several other fungal diseases of sugarcane, attempts to artificially induce this disease have limited success. To address this gap, field studies were conducted at the Sugarcane Research Farm in Kalyanpur (RPCAU, Pusa, Samastipur) during the 2023-24 cropping season to simulate wilt under field conditions using thirty-five sugarcane varieties along with a highly susceptible check variety (CoV 92102). All varieties were assessed for their responses to the wilt pathogen using 0 - 4 scale of wilt severity index. Among various inoculation methods, the plug method proved to be the most effective, as it clearly differentiated resistant, moderately resistant, moderately susceptible and susceptible varieties with balanced distribution across all categories. It recorded 20 % resistant, 28.58 % moderately resistant, 37.14 % moderately susceptible and 14.29 % susceptible varieties, thereby providing a realistic assessment of varietal response. In comparison, the soil and sett dip methods showed higher proportions of resistant and moderately resistant categories but fewer susceptible varieties, while the cotton swab method largely favoured resistance (94.29 %), masking the true susceptibility of many varieties. Hence, the Plug method is considered the best and most reliable technique for evaluating sugarcane resistance against wilt disease because it exposes pathogenic variability more effectively and avoids overestimation of resistance.