In vitro antimicrobial activity and alternative control of anthracnose in papaya

ABSTRACT: We evaluated the efficacy of natural products in the control of papaya anthracnose, in vitro and in vivo. The in vitro experiments for evaluation of mycelial growth used a completely randomized 10 × 4 factorial design (treatments × evaluation periods) with eight replicates, with sporulation evaluated at the end of the experiment. The treatments involved the use of aqueous extract at concentrations of 5 and 15% for Syzygium aromaticum (L.) Merr. & Perry (clove), Cinnamomum zeylanicum Breym (cinnamon), and Zingiber officinalis Rox. (ginger); 1 and 3% chitosan; the fungicide Prochloraz at 100 µg.mL-1; and a control (no treatment). For evaluating conidia germination, we used six treatments with five replicates. The treatments included 7.5% of each extract (clove, cinnamon, and ginger), 1.5% chitosan, and 50 µg.mL-1 of Prochloraz. For the in vivo experiment, “Formosa” papaya “Tainung 1” was used in a completely randomized design, with six treatments and four replicates to evaluate the severity of anthracnose caused by Colletotrichum gloeosporioides. The fruits were treated by immersion for 5 min with 15% clove, cinnamon, and ginger extracts, 8% chitosan, and control with distilled water, and immersion for 2 min in Prochloraz (33.75 g a.i./100 L). The treatments with 15% clove extract and 8% chitosan were effective in all evaluations, resulting in a viable alternative to the fungicide Prochloraz. The treatments with ginger extract were less effective and those with cinnamon offered intermediate control.

摘要：本研究评估了天然产物在体外及体内条件下防治番木瓜炭疽病的应用效果。用于测定菌丝生长的体外实验采用完全随机10×4因子设计（处理组×评估周期），设置8次生物学重复，于实验结束时统计产孢量。处理组包含：丁香（Syzygium aromaticum (L.) Merr. & Perry）、锡兰肉桂（Cinnamomum zeylanicum Breym）与生姜（Zingiber officinalis Rox.）的水提取物，浓度分别为5%与15%；浓度1%与3%的壳聚糖；100 µg·mL⁻¹的咪鲜胺（Prochloraz）杀菌剂；以及空白对照组（不施加任何处理）。针对分生孢子萌发的评估实验共设置6组处理，每组5次重复，处理组包括7.5%的上述三种植物提取物各1组、1.5%壳聚糖组，以及50 µg·mL⁻¹的咪鲜胺组。体内实验采用完全随机设计，以‘台农1号’福摩萨番木瓜为供试材料，设置6组处理、4次重复，用于评估胶孢炭疽菌（Colletotrichum gloeosporioides）引发的炭疽病病情严重程度。供试果实分别经以下药剂浸果处理5分钟：15%丁香、肉桂、生姜提取物，8%壳聚糖，以及蒸馏水空白对照；另以33.75 g有效成分/100 L的咪鲜胺药液浸果2分钟。试验结果显示，15%丁香提取物处理组与8%壳聚糖处理组在所有评估周期中均表现出显著的防治效果，可作为咪鲜胺杀菌剂的可行替代方案；生姜提取物处理组的防治效果相对较弱，肉桂提取物处理组则展现出中等水平的病害防控效果。