Comparative efficacy of inoculation methods and agrochemicals in managing citrus canker (Xanthomonas axonopodis pv. citri)

Citrus canker caused by Xanthomonas axonopodis pv. citri (Xac) is causing extensive damage in nursery and orchard. The disease renders nursery stock unfit for propagation. Of the three methods of inoculation, namely pin prick, clipping and spray; pin prick was found most effective. The diagnostic symptom appeared after 35 and 45 days of inoculation in Rough lemon and Kinnow mandarin seedlings, respectively. Six agrochemicals viz. Bactrinashak, Blitox, Bordeaux mixture, Copper sulphate, Kocide and Streptocycline were evaluated in vitro and in vivo against canker disease. Streptocycline at 5 ppm was found significantly effective against Xac. The ed₅₀ value of Streptocycline and Blitox were > 50 ppm. Streptocycline sprays @100 ppm were found significantly effective in checking the disease in Kinnow mandarin. The second best were copper fungicides (Blitox and Bordeaux mixture). The order of ranking of agrochemicals against Xac was Streptocycline < Bordeaux mixture < Blitox < Kocide < Bactrinashak.