2.1. Fungal Isolates The virulent isolate of a tomato leaf spot fungus Alternaria alternate, a chilli pepper anthracnose fungus Colletotrichum gloeosporioides, a tomato wilt fungus Fusarium oxysporum fsp. lycopersici, a tomato crown and root rot fungus Sclerotium rolfsii, a tomato late blight fungus Phytophthora infestans and a seedling damping-off fungus Pythium sp. were collected from their corresponding infected host plant in the production fields at Nongkai Province, Northeastern Thailand. The obtained fungal isolates were identified according to their unique morphological and cultural characteristics as described by Barnett and Hunter in the year 1986 [6]. The pathogenicity of each was proven by repeat-inoculation on its host plant. Pure subcultures of these isolated fungi were then maintained on potato dextrose agar (PDA) medium at 4˚C for further studies