The role of soil fungi and Bacillus in the Chinese fir (Cunninghamia l
anceolata) replant problem was investigated. Several pathogenic fungi
isolated were more abundant in replant than in non-replant woodland so
il, but the species composition of soil bacteria showed no significant
differences. Fumigation of replant soils with methyl bromide signific
antly increased the growth of Chinese fir compared with nonfumigated s
oils. Inoculation of steam-sterilized soil with the pathogenic fungi c
aused significant reduction of growth of Chinese fir seedlings, while
amendment with bacteria from the soil had no effect on seedling growth
. However, the combination of pathogenic fungi and bacteria greatly re
duced plant growth and increased root rot compared with pathogenic fun
gi or bacteria alone. It is suggested that fungi alone or in combinati
on with bacteria may be important biotic factors in the Chinese fir re
plant problem.