Abstract
Conidia of Sphaeropsis sapinea were trapped in pine plantations in regions of South Africa with summer, winter, and constant rainfall. Spore traps, made from microscope slides coated with petroleum jelly, were collected weekly over a year. Vertical slides trapped conidia deposited by impaction and were more efficient than horizontal slides that trapped those deposited by sedimentation. There was no direct relationship between mean maximum monthly temperature and monthly spore count for any of the regions. Although dispersal of S. sapinea conidia was strongly related to the occurrence of rainfall, peak conidia dispersal in the three regions succeeded peak rainfall by up to 16 wk. Maximum conidial production occurred in spring (October) in the winter rainfall region, in early summer (December) in the constant rainfall region, and in late summer (February) in the summer rainfall region. These results suggest that, in all three climatic regions, winter is the most desirable time for management operations such as pruning that favor infection by S. sapinea.

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