Powdery mildew and leaf mold were major diseases in organic cultured tomatoes. NaHC03 and KH2P04 were selected as control agents for controlling tomato powdery mildew. Control effect of the selected control agents was increased when they were tréated with oil-egg yolk mixtures (OEYO). Also four organic materials used commercially including copper hydroxide and sulfur showed high control effect more than 90% in green house. Also two organic matters, copper hydroxide and sulfur showed high control effect in farmer's field. When tomatoes were cultivated in plastic house installed wìth circulation fan, incidence of powdery mildew and leaf mold was reduced by 56% and 60%, respectively.

• Yong-Ki Kim(Organic Agriculture Division, National Academy of Agricultural Science, RDA, Suwon, 441-707, Republic of Korea)
• Sung-Jun Hong(Organic Agriculture Division, National Academy of Agricultural Science, RDA, Suwon, 441-707, Republic of Korea)
• Hyeong-Jin Jee(Organic Agriculture Division, National Academy of Agricultural Science, RDA, Suwon, 441-707, Republic of Korea)
• Jong-Ho Park(Organic Agriculture Division, National Academy of Agricultural Science, RDA, Suwon, 441-707, Republic of Korea)
• Eun-Jung Han(Organic Agriculture Division, National Academy of Agricultural Science, RDA, Suwon, 441-707, Republic of Korea)
• Nan-Hee An(Organic Agriculture Division, National Academy of Agricultural Science, RDA, Suwon, 441-707, Republic of Korea)
• Eun-Jung Choi(Organic Agriculture Division, National Academy of Agricultural Science, RDA, Suwon, 441-707, Republic of Korea)
• Kyoung-yul， Ryu(Microbial Safety Division, National Academy of Agricultural Science, RDA, Suwon, 441-707, Republic of Korea)