Chemical and cultural control of bacterial blossom blight of kiwifruit caused by Pseudomonas syringae in Korea

Disease incidence of bacterial blossom blight (Pseudomonas syringae van Hal l) ranged from 13.0 to 36.2% in naturally infected kiwifruit (Actinidia del iciosa (A. Chev) C. F. Liang et A. R. Ferguson) orchards of the major kiwif ruit-growing areas in Korea from 1997 to 1999. A significant correlation oc curred between disease incidence and rainfall at flowering. Several control practices were compared with conventional chemical control to prevent bact erial blossom blight of kiwifruit. Streptomycin sulfate + oxytetracycline W P applied 3 times at 10-day intervals resulted in control efficiencies from 75.6 to 79.8% in 1997 and 1998, respectively. Trunk injection of various c oncentrations of acetic acid also displayed variable control efficiencies. Injection with 7% (v/v) acetic acid was the best injection treatment with c ontrol efficiencies from 70.9 to 77.0%. Use of a transparent polyvinyl film to protect kiwifruit trees from rain or girdling of trunks of kiwifruit tr ees alleviated the diseases at rates of 61.0-84.7 or 65.7-76.8%, respective ly. The results suggest that trunk injection of acetic acids, girdling on t runks, and rainproof installation over kiwifruit trees can be applied as re asonable control practices to manage bacterial blossom blight in kiwifruit orchards in Korea.