2016 Volume 62 Pages 56-63
In 2013, clubroot disease on cabbage and ornamental turnip rape for landscape was observed in Ibusuki City, whereas there had been no report of the disease since 2001 when the first incidence was reported in Kagoshima Prefecture. According to the present survey, instances of the disease were observed in eight districts of Kagoshima and there were many infested fields clustered in Ibusuki City, whereas there were few fields infested in other districts. The severity level of these infested fields was relatively low with a range of resting spore densities from 103 to 104/g soil. Averages of the soil pH in each field ranged from 5.5 to 6.3 hence there were no suppressive field soils this pH values exceeding 7, and in some fields the incidence of clubroot might be promoted by soil with a low phosphate absorption coefficient. The virulence of field isolates of resting spores was relatively weak thus the introduction of CR cultivars seems to be an effective tactic to solve with problem.
