蘆筍莖枯菌腐生力之研究

Study on Saprophytic Activity of Phoma asparagi Sacc.

蘆筍莖枯病菌可於六種高壓殺菌後之植物殘體上腐生並形成柄子器。然而在未經殺菌之供試植物殘體上只能在蘆筍、紫花首蓿及玉米殘體上腐生。柄子器之數目，大小及形成之時間均以蘆筍為佳，並隨所腐生之植物殘體而異。病菌在蘆筍殘體上之腐生力隨不同程度之殺菌，表面消毒及洗滌而下降如高壓殺菌、氧化丙烯，次氯酸鈉、酒精、無菌水、蒸餾水處理。在殺菌土中，病菌於土壤含水量5～30%（w/w）能定殖於蘆筍莖片段上，未殺菌土壤則只能在15～25%含水量範圍下腐生。試驗結果顯示病菌能在自然界中腐生存活並成為田間感染源之一。

Phoma asparagi Sacc. could grow and form pycnidia on six autoclaved plant residues saprophgtically. However, pycnidia were found only asparagus, alfalfa and corn in six test unsterilized plant residues. The number, size and time of pycnidia formation were optimum on asparagus stems and varied dependent on the residues on which the pathogen saprophytically grown. The sarpophytic activity of the fungus on asparagus stem segments decreased in the descending order of different degree of sterilization, surface disfestation and washing treatments such as autoclave, propylene oxide, sodium hypochlorite, ethyl alcohol, sterilized water, and distilled water, respectively. In sterilized soil, the pathogen could colonize on asparagus stem segment within 5 to 30% (w/w) moisture content. However, it was reduce to 15 to 25 % moisture content in unsterilized ones. The results indicated that P. asparagi may sarpophytically grow in field for survive and serve as a source of inoculum.