기생잡초 새삼류의 분포와 기주범위 및 미국실새삼의 발아특성을 구명한 결과, 자생종인 새삼, 실새삼, 갯실새삼은 거의 분포하지 않은 반면에, 외래종인 미국실새삼은 넓게 발생하고 있었다. 미국실새삼의 기주식물 범위는 도라지, 콩 등 127종으로서 넓었다. 미국실새삼 종자는 20∼35 범위에서 발아율이 높았고 발아속도도 빨랐다. 미국실새삼 유묘는 3cm 이내의 토양깊이에서 50%이상 출현하였다.Surveys were conducted to establish the current distribution pattern and host range on four species of genus Cuscuta in southern parts of Korea. Cuscuta japonica, C. australis and C. chinensis were rare native species, but C. pentagona, exotic species, was widespread in natural habitats. In southern parts of Korea, C. pentagona has been recorded as a parasite on 127 herbaceous and woody plants. Soaking C. pentagona seeds in concentrated sulfuric acid was very effective on its germination. Seeds of C. pentagona germinated at constant temperature from 15 to 35 with optimum germination at 30 and 35 , and at alternate temperature from 20/10 to 35/25 (day/night; 12/12hrs.) with optimum germination at 35/25 . Seedlings of C. pentagona were emerge at soil gravimetric water content from 10 to 30% with optimum emergence at 20 and 30%. Seedlings of C. pentagona were able to emerge from depths as great as 6cm.