Seasonal Response ofPinus radiatain South Africa to Artificial Inoculation withSphaeropsis sapinea

Trials were conducted in the winter rainfall region of South Africa to determine the effect of season on the rates of colonization of pine tissue by three isolates of Sphaeropsis sapinea. Four-year-old Pinud radiata trees were inoculated during fall and spring in 1986 and 1987. In both years, cambial lesions caused by S. sapinea on trees inoculated in spring were significantly longer than those on trees inoculated in fall. There was a significant interaction (P<0.01) between seasons and isolates