Leaf-disk method for assessment of disease severity of lily leaf blight caused by Botrytis elliptica

Abstract

A leaf-disk assay was developed for disease assessment of lily leaf blight caused by B o t rytis elliptica. Oriental hybrid lily (cv. Star Gazer) grown from bulbs in a greenhouse for 1.5 to 2 months was used to prepare leaf disks. The fifth to tenth leaves below the apex were surface-disinfested by dipping entire leaves into 0.1% (v/v) sodium hypochlorite three times and rinsed in sterile water after each dip. Leaf disks (15-mm diameter) were then perforated from surface-disinfested leaves with a cork borer, and fully submerged in fungicide or antagonist solutions. The disks (8 per replication) were placed abaxial surface side up in petri dishes containing a piece of 60-mm-diameter sterilized filter paper. Two milliliters of sterile water were added to the filter paper to maintain moisture. Spore suspension of B. elliptica was adjusted to 105 spores per ml and was sprayed over the disks as inoculum, then the disks were incubated in 20℃ incubator without light. After 3 days incubation, disease severity was assessed as percent necrotic area. The results of the leafdisk assay were consistent and agree with that of whole plant assays in the greenhouse. 採取露蕾期之葵百合( c v. Star Gazer) 葉片，以口徑15 mm之打孔器切取葉片圓盤，評估灰黴病菌[ B o t rytis elliptica (Berk.) Cooke ] 為害百合葉片的情形，包括決定接種源的濃度、溫度對病害發生之影響、噴霧接種之水珠大小、植株葉位之感病性，及葉片圓盤分析法與整株百合罹病之相關性。建立一個葉片圓盤分析的標準方法：即摘取成熟百合植株之第五至十位葉，以0 . 1 %次氯酸鈉表面消毒後，經無菌水漂洗三次，晾乾後以口徑15 mm打孔器切取葉片圓盤，置於平舖一張6公分之濾紙且含2毫升無菌水之9公分培養皿中，每皿置放8片葉片圓盤，然後接種每毫升含1×1 05個灰黴病菌之胞子懸浮液，使圓盤上覆一層大小約0.3 mm之水珠，覆以皿蓋，移置於2 0℃之定溫箱中觀察病勢的進展。在室內利用葉片圓盤分析法篩選百合灰黴病菌的防治藥劑與拮抗微生物，結果與溫室測試整株植物之結果相當一致。葉片圓盤分析法不但可減少植材與葉片用量外，並可節省試驗空間與時間，且可預先篩選出防治百合灰黴病菌的藥劑與拮抗微生物，以供溫室或田間進一步試驗之用。