Before transplanting Chinese cabbage seedlings, two kinds of eggshell powder were blended into the soil of cabbage
field where the clubroot pathogen, Plasmodiophora brassicae, was infested. The incidence of clubroot disease,
the shoot and root growth of cabbages, and soil pH were examined four times at 10 to 13 days interval
from transplanting Chinese cabbage. As results, the cabbages treated with eggshell powder without membrane
showed the fastest growth in above ground part, and the lowest disease index for clubroot disease. The cabbages
treated with eggshell powder with membrane showed better growth than the cabbages of non-treated
check, but lower growth than those treated with eggshell powder without membrane. Soil pH started to
increase from 3 weeks after soil blending of eggshell powder, and it reached to above 8.0. However, the soil pH
of non-treated check stayed at around 6.8. In the experiment to compare the effect of eggshell powder with
other calcium compounds, soil-blending of CaCO3 resulted the lowest disease incidence of 1.7 and the registered
fungicide, ‘flusulfamide’, and the resistant variety ‘CR Green cabbage’ followed with the incidence of 1.9.
Cabbages of non-treated check scored the highest disease incidence, 3.4, and that of eggshell powder without
membrane was as high as 2.7. However, the growth of Chinese cabbage showed the different pattern to the disease
incidence. Chinese cabbages treated with eggshell without membrane recorded the highest average
growth, around 2.1 kg. On the other hand, the average growth of CR Green Chinese cabbage was about 2.0 kg,
that of flusulfamide-treatment plot was 1.7, and that of non-treated check was as low as 1.3 kg. Soil blending of
eggshell powder without membrane did not inhibit the development of clubroot, but increased the growth of
cabbage to a great extent. Therefore, it was confirmed that soil blending of eggshell powder before transplanting
makes the Chinese cabbage culture possible even in the field infested with clubroot pathogen.