由Sclerotium rolfsii 引起之菱角白絹病是目前菱角主要病害之一。本研究之目的在探討菱角白絹病之生態及其防治法，研究結果顯示菱角白絹病病原菌之菌絲生長及菌核發芽之最適溫度均為24∼32℃。病原菌於菱角葉片上當氣溫在24∼32℃時病勢擴展最快，任何株齡的菱角植株均可發病。菌核埋在2公分土中可殘存6個月以上，而在水中可殘存9個月。由田間菌核的消長，白絹病的發生及溫度的變化，得知田間的菌核密度較高時，則罹白絹病的機率也較高，而且溫度24℃以上及植株生長繁密均為促進病勢發展的主因。針對目前植保手冊所推荐使用於其他作物有關病害之防治藥劑中，共收集了八種藥劑進行室內篩選、盆栽試驗及田間試驗，結果顯示50％ Moncut W.P. 3000倍及75％ Basitac W.P. 1000倍的防治效果最好。清除田間罹病株及殘體，以及適時疏苗避免枝葉重疊隆起與配合化學藥劑的使用，即可有效地控制菱角白絹病的發生。
Ecology and Control of Sclerotium Rot of Water Caltrops (Trapa taiwanensis)
Cheng, A. H. and S. C. Chen
Sclerotium rot caused by Sclerotium rolfsii is one of the most import diseases of water caltrops (Trapa taiwanensis L.). This study was attempted to study the ecology and control of Sclerotium rot of water caltrops. The results showed that optimum temperatures for mycelial growth and sclerotial germination were between 24 and 32℃ and the best temperatures for disease development were found between 24 and 30℃. The disease was found in all growth stages of the plants. Sclerotia survived more than 6 and 9 months, respectively, in the soil 2 cm below surface and in the water. Occurrence of the disease and sclerotia fluctuation of S. Rolfsii were observed in a water caltrops field between 1987 and 1989. It was found that the more the sclerotia were existed in the field, the more the plants were infected. The temperature over 24℃ and excessive growth of plants were the key factors limiting the development of the disease. Results of the field tests indicated that 50% of Moncut W.P. 3000x and 75% of Basitac W.P. 1000x were effective to control this disease.