Abstract The effects of root exudates of purple and white garlic（Allium sativum L.）at different seedling ages，including different concentrations of aqueous garlic extract and the ethyl acetate extract on pepper Phytophthora blight caused by Phytophthora capsic，strawberry gray mold caused by Botrytis cinerea and tomato bacterial wilt caused by Pseudomonas solanncearum Smith were investigated．The best inhibitory effects were found using the root exudates of 20-30 d purple and white garlic on all 3 soil-borne pathogens．While 5.00 mg?mL-1 of purple garlic water extract can completely inhibite the pepper Phytophthora blight and the colony growth of strawberry gray mold．Higher concentration of water extract from white garlic，e.g．20.00 mg?mL-1 is needed to exert the same effect．On the other hand，the minimum inhibitory concentration（MIC）of ethyl acetate extract from purple garlic can inhibit completely the pepper Phytophthora blight and the strawberry gray mold with 5.00 mg?mL-1 and 2.50 mg?mL-1，respectively．However，the higher concentration of the ethyl acetate extract from white garlic at 10.00 mg?mL-1 and 20.00 mg?mL-1，respectively are required to inhibit the 2 pathogens to the same extent as by purple garlic．20.00 mg?mL-1 of ethyl acetate extracts from 2 garlic varieties are required to suppress tomato bacterial wilt.
