Epidemiological Studies on Bacterial Blossom Blight of Kiwifruit

4. Relationship between Disease Incidence of Bacterial Blossom Blight and Meteorological Factors

Abstract

Effect to the various meteorological factors on the occurrence of bacterial blossom blight of kiwifruit was statistically analyzed in 9 years from 1987 to 1995. Growth stage of the plant was classified into six stages by 10 days interval from flowering to 60 days before flowering. Meteorological factors used were as follows; temperature (T), maximum temperature (T_max), minimum temperature (T_min), difference in maximum and minimum temperature (DT), relative humidity (RH), minimum relative humidity (RH_min), hour of sunshine (HS), amount of insolation (AI), precipitation (P) and days of rainfall (DR). Flowering stage positively correlated (P<0.05) with disease incidence. Twelve meteorological factors showing correlation coefficient greater than 0.5 were T, T_max, H, P and DR at stage 2, DT, RH, RH_min and AI at stage 3, T_min at stage 4 and T and T_max at stage 5. When these 12 factors were analyzed multiple regression by foreword selection method, five factors were found to have significant probability at least 5% level; P and T_max at stage 2, DT and RH at stage 3 and T at stage 5. R² of the 5 factors was calculated to be 61.2%. These results suggest that account for the occurrence of bacterial blossom blight above 5 factors, especially from 10 to 29 days before flowering.