摘要
迷迭香是為香草業者中重要的經濟作物之一，通常在夏天高溫多濕的環境下，易造成根腐病（Root rot），導致地上部黃化、枯死，經由鏡檢迷迭香根部組織，可在根部組織中發現卵孢子（Oospore）或厚膜孢子（Chlamydospore）等構造，初步懷疑係由卵菌綱（Oomycete）所引起，於是以選擇性培養基進行迷迭香根的病健部組織分離，所分離到的約120株分離株中，經初步鑑定出 Pythium 及 Phytophthora，且以 Pythium 之分離檢出率達98 ％ 為最主要，Phytophthora 之分離檢出率為2 ％。將所有120分離株依外部型態特徵做初步的鍵定與分群，共得20群，再逐一鑑定出其中有 Pythium 6種， Phytophthora 2種，此8種經分別接種於試管中已發根迷迭香扦插苗及穴盤介質栽培扦插苗，以檢定其病原性，結果發現，其中5種 Pythium 及2種 Phytophthora 皆具病原性，且兩類中分別以 Pythium myriotylum 及 Phytophthora nicotianae 最為主要。在藥劑防治上，以浸泡迷迭香盆栽地下部根系的方式，各施予500X鋅錳乃浦及500X甲基多保淨，浸泡時間分別為10秒、20秒及60秒，結果顯示，在浸泡鋅錳乃浦20秒與甲基多保淨10秒，皆有良好的防治效果。而以滴管澆灌此兩種農藥的方式，以檢定藥害情形，亦發現藥害情況並不明顯。在迷迭香所分離到的較強病原性的菌株中，選定腐霉菌 P. myriotylum 、 P. ostracodes 、 P. catenulatum 及疫病菌 Ph. nicotianae ，分別接種於甘藍、番茄和包心芥菜等3種蔬菜幼苗作物，其結果皆顯示可造成此3種蔬菜之根腐病徵。而在本研究中，已經由柯霍氏準則的驗證，證明迷迭香根腐病之發生、病原性和真菌種類，此對迷迭香根腐病的了解及後續之防治將有所幫助。
並列摘要
Rosemary is one of the economically important fragrant herbs in agricultural industry. In warm and wet summer in Taiwan, however, rosemary is frequently affected with a root rot disease. The disease symptoms include leaf yellowing, wilt, and root browning. Under a microscope, we can find a lot of oospores and chlamydospores in the root tissue. Therefore it was thought to be caused by fungi of the family of Oomycetes. Selective medium developed by Ko et al for isolation of Pythium and Phytophthora was then used to isolate the suspect pathogen from browning roots from about 60 diseased plants. A total of 120 isolates were obtained from these 60 diseased rosemary plants, and among them 98 ％ were Pythium , only 2 ％ were Phytophthora . These 120 isolates were tentatively divided into 20 groups according to their morphology and other characteristics. Results showed that these isolates consisted of 6 species of Pythium and 2 species of Phytophthora . Among them 5 species of Pythium and both Phytophthora were pathogenic to roots of seedlings in test tubes and in pots, or inoculated to healthy pot seedlings. Pythium myriotylum and Phytophthora nicotianae were the dominant species, for these respective genus. The fungicides mancozeb and thiophanate methyl each at 500X concentration were applied by dip every the whole diseased plants for 10, 20 or 60 seconds. Results showed that mancozeb dipping for 20 seconds and thiophanate methyl dipping for 10 seconds are satisfactory for curing the disease. There two fungicides were not phytotoxicity to rosemary. Four root rot pathogens of rosemary including Py. myriotylum, Py. oedochilum, Py. catenulatum, and Ph. nicotianae were also used to inoculate healthy seedlings of cabbage, tomato, and mustard. They all showed root-browning symptom, after the inoculation. In conclusion, the Koch`s postulates of this disease has been proven, and the pathogens were identified. It should benefit the diagnose and control the disease in the future.