木瓜蒂腐病菌生理特性及防治藥劑之篩選

Abstract

國立高雄師範人學生物科學研究所;嘉義分所;國立嘉義大學生物科技研究所蒂腐病為木瓜常見之採收後病害，由Lasiodiplodia theobromae (Pat.) Griffon & Maubl. (=Botryodiplodia theobromae Pat.)所引起。本研究測試木瓜蒂腐病菌在人工培養基上的生理特性，並篩選防治用之藥劑，以供田間防治木瓜蒂腐病之所需。L. theobromae菌絲生長的最適溫度為30℃，而產生柄子殼的最適溫度則為25℃。測試之8種不同培養基中，以PDA最適合菌絲生長及產生柄子殼。本菌之營養需求以碳素源中之葡萄糖、果糖及蔗糖最適合菌絲生長；氮素源則以硝酸鉀和硝酸鈉對菌絲生長有促進作用。防治用藥劑之篩選以賽普護汰寧(cyprodinil + fludioxonil)、護矽得(flusiazol)、得克利(tebuconazole)、撲克拉(prochloraz)及依普同(iprodione)等對病原菌的菌絲生長有較強的抑制效果，各藥劑的半致死濃度均在l mg/L以下。而市售之生物製劑台灣寶（枯草桿菌Bacillus subtilis Y1336）及安心寶（放線菌Streptomyces candidus Y21007-2）對蒂腐病菌之菌絲生長也有明顯抑制作用。此外，選用賽普護汰寧、護矽得、台灣寶與安心寶等葯劑施用於人工接種之木瓜果實，結果皆具有明顯之保護作用。 Stem-end rot is a postharvest disease of papaya, and is caused by Lasiodiplodia theobromae (Pat.) Griffon & Maubl. (= Botryodiplodia theobromae Pat.). The objectives of present study are to assay physiological characterization and to screen chemicals for the control of this pathogen. The optimum temperature for mycelial growth and pycnidia formation of L. theobromae were 30 and 25 , respectively. Among 8 tested media, PDA was the best medium for mycelial growth and pycnidia formation. When the medium was amended with dextrose, fructose and sucrose as the carbon source, and potassium nitrites, sodium nitrites as the nitrogen source, the mycelial growth of the pathogen were significantly promoted. Fungicides were evaluated in vitro for their ability to inhibit mycelial growth of the pathogen. Fludioxonil + cyprodinil, flusiazol, tebuconazole, prochloraz and iprodione showed a better inhibitory effect on pathogen growth, the effective concentration of 50% inhibition (EC50) of these chemicals were less than 1 mg/L. Both commercial biological agents, Bacillus subtilis Y1336 and Streptomyces candidus Y21007-2, were shown to be antagonistic to pathogen growth. While cyprodinil + fludioxonil, flusiazol, and two biological agents were tested for their control efficacy on diseased papaya fruits, the results suggested that these treatments could effectively protect papaya fruits against pathogen infection.