A very destructive lily disease was occurred at Daekwallyong alpine areas in 1999. We have performed experiments to identify the causal pathogen of lily disease and to find a way to control the disease chemically. Twelve fungal isolates from the infected lily were identified as Phytophthora cactorum. Mycelial growth of all isolates were completely inhibited on potato dextrose agar with $10{mu}g/mL$ metalaxyl. Among 11 fungicides tested, $10{mu}g/mL$ of dimethomorph, ethaboxam, and oxadixyl inhibited mycelial growth of P. cactorum. PC-1. Therefore, spray of phenylamide fungicides such as metalaxyl and other commercial fungicides should be a effective way to control the Phytophthora blight of lily.