We compared the spatial distribution of stem cankers on the canopy tre
e Ocotea whitei (Lauraceae) in a 20-ha plot on Barro Colorado Island,
Panama, with spatial and temporal patterns of mortality in this host o
ver the previous decade. The cankers occur both on adult and juvenile
individuals, although juveniles are much more likely the adults to sho
w symptoms. Disease incidence is host-density dependent, and both the
presence of the disease and host mortality are more likely close to th
an far from a conspecific adult, which resulted in a net spatial shift
of the juvenile population away from conspecific adults through time.
Disease incidence is lower than expected among juveniles of 0. whitei
growing near to adults of the non-susceptible canopy tree Beilschmied
ia pendula. The coincidence of spatial patterns of canker incidence an
d host mortality suggest a role for the disease in regulating host spa
tial distribution, in agreement with predictions of the Janzen-Connell
hypothesis.