ABSTRACT
Seventy isolates representing six species of Trichoderma were tested for linear growth rates at five temperatures (5–25 C). Growth rate varied substantially within and among species. Multivariate procedures were used to distinguish species on the basis of their growth rates. The ability of nine isolates to kill Phellinus weirii was tested in vitro at 10 and 20 C. Isolates of T. viride, T. polysporum, and T. harzianum were more antagonistic to P. weirii than were isolates of the other three species. The T. harzianum isolate killed P. weirii fastest at 20 C, whereas the T. viride and T. polysporum isolates acted most rapidly at 10C. Techniques used here to assay antagonism can be extended to test more isolates, both in vitro and in the field.