芒果炭疽病之生物防治

Abstract

於1993 ~ 1996 年間，連續在室內及田間測試拮抗細菌與酵母菌對芒果炭痘病的防治效果。四株拮抗細菌和五株括抗酵母茵(包括BaciJJus subti1is, Pseudomonas fJ uorescens, Pichia ohmeri, Sporobolomyces sp. ，及unidentified yeast) 與病原茵同時接種於芒果傷口時，均能顯著抑制炭痘病斑的擴展，平均減少20%-45%，其中以B. subtilis (Tp-Tu311) , P. fJ uoresce.ns (TN-S221)與P. ohmeri (Y24-8) 等三個拈抗菌株能穩定而有效的抑制病斑擴展。此三菌株在芒果開花時噴施於花穗上，Y24-8 能顯著提高著果率。套袋前將此三菌株噴施於芒果果實上，較殺菌劑Bavistin 或Bavistin+oil 更能減少採收後果實炭痘病的發生率。噴施措抗菌並加以套袋的防治炭痘病效果較連續噴藥直到採收但不套袋者為佳。TN-S221，Tp-Tu311 與Y24-8 三株括抗菌若作果實的俊熟處理，亦有減少發病的趨勢，而以Tp-Tu311 效果較佳。測試措抗菌Tp-Tu311，TN-S221與Y24-8對炭瘟病茵茵絲生長與胞子發芽及附著器產生之影響，抵有Tp-Tu311會抑制茵絲生長，其餘兩者不會，且Tp-Tu311先在培養基培賞一段時間後，再加入病原菌的抑制效果較佳。三株拮抗菌均不會抑制胞子發芽與附著器形成，但均會使其變形。Tp-Tu311的作用特別明顯，可使發芽管和附著器膨大如疣狀，Y24-8 的作用不明顯，但會緊密貼附在胞子及發芽管的周圍。 Antagonistic bacteria and yeasts were investigated for control of mango anthracnose disease in laboratory and in field during 1993-1996. Four antagonistic bacterium isolates and 5 yeast isolates, including Bacillus subti1is, Pseudomonas f1uorescens, Pichia ohmeri, SporoboJomyces sp. and unidentified yeast, were indi vidually assayed against Colletotrichum gloeosporioides by coinoculating antagonist and pathogen in artificial wounds of mango fruits. Results showed that all test antagonists were able to inhibit lesion expansion of mango anthracnose significantly by reducing 20 % -45 % of lesion size in average. Among nine test antagonists, B. subtilis (Isolate Tp-Tu311), P. f1uorescens (Isolate TN-S221) and P. ohmeri (lsolate Y24-8) were consistent and effective to inhibit lesion expansion at three separate experiments. Isolate Y24-8 significantly increased fruit set when these 3 antagonistic isolates were sprayed onto mango inflorescence. Compared with fungicide Bavistin and Bavistin+oil treatment, these antagonists also significantly reduced anthracnose development of ripening fruits after harvest when the fruÏt was sprayed with antagonists before bagging in field. Efficacy of control for mango anthracnose by spraying antagonists and bagging was better than by spraying fungicides but not bagging. Postharvest treatment of mango fruit with antagonists TN-S221 , Tp-Tu3 11 and Y24-8 tended to decrease the anthracnose development and Tp-Tu311 was the best for controlling the disease. These 3 antagonists did not affect conidial germination and appressorial formation of the fungus, and only Tp-Tu311 inhibited mycelial growth. Swelling of germ tubes and appressoria was obviously occurred when Tp-Tu311 was added into conidial suspension of the fungus. However, this phenomenon was less observed in TN-S221 and Y24-8 treatment. Many cells of Y24-8 were able firmly to attach to spores and germ tubes of the pathogen.