root and butt rot diseases caused by the fungal pathogens armillaria ostoyae and heterobasidion irregulare, result in substantial economic and ecological losses to pine plantations across southcentral ontario, canada. biocontrol agents like hypholoma species and phlebiopsis gigantea offer potential solutions for managing these diseases. however, their effectiveness against these pathogens is highly influenced by key abiotic factors such as temperature and soil ph. i investigated the impact of temperature and ph on the growth of fungal pathogens a. ostoyae (strains: b249-28 and p162-7) and he. irregulare, in the presence and absence of biocontrol species and strains of hypholoma spp. (hypholoma fasciculare, hy. sublateritium, hy. capnoides) and phlebiopsis gigantea. single and paired colony in vitro experiments were conducted using 2% malt agar media at 2, 10, 15, 20, 25, and 30°c, and ph levels of 5.0, 6.0, 7.0, and 8.0 to compare and contrast growth responses in the absence and presence of competition between the pathogens and their respective biocontrol species and strains. [...]