The occurrence of Lophodermium on fallen needles and Leptostroma,
the mitosporic state of Lophodermium, on living needles of
Japanese black pine trees treated with simulated acid rain (SAR, pH 3)
or tap water (control, pH 6·3) were studied. The amount of
fallen needles was also examined. Significantly more needles fell from
SAR-treated trees than from control trees, though there were
no visible symptoms in the needles of SAR-treated trees. The detection
frequency of Lophodermium on fallen needles, and that of
endophytic Leptostroma on 2 year old and 3 year old needles, was
lower in SAR-treated than control trees. The reduction in the
detection of Lophodermium/Leptostroma on needles
implied the reduction in the density of endophytic fungi with air pollution.