非農藥資材防治甘藷基腐病之研究

Study of non-pesticide control on foot rot disease of sweet potato

陳學弘(Hsueh-Hung Chen)

指導教授 ： 孫岩章

國立臺灣大學/生物資源暨農學院/植物醫學碩士學位學程/碩士(2017年)

https://doi.org/10.6342/NTU201702454

摘要

甘藷基腐病為近年台灣甘藷栽培中首要危害，本病由 Phomopsis destruens 引起，可造成莖基部產生黑褐色腐爛，向上造成地上部黃化枯萎進而死亡，此外基腐病亦會向下感染甘藷塊根，使甘藷呈水浸狀腐爛，完全失去商品價值。雖然基腐病已於 2016 年公布 2 種正式藥劑，但近年來由於國人對於食品安全、農藥殘留及環境永續等議題日漸重視，化學農藥減少使用已成為普遍趨勢。因此，本研究欲了解台灣北部甘藷栽培現況與基腐病發病情形，同時篩選出具有防治潛力的非農藥資材，並比較其與化學藥劑防治甘藷基腐病的效果。根據調查，2016 年金山萬里甘藷豐收，基腐病造成的損失較少，又因同年一月底全台爆發霸王級寒流，故欲了解低溫逆境是否影響基腐病菌殘存。結果顯示，將基腐病發病藤蔓於 4℃ 低溫處理 5 天病原菌分離率即減至 20%，但至 14 天仍可分離出基腐病菌，分生孢子於低溫處理 14 天發芽率減為約 43%，故推測低溫逆境對基腐病菌的殘存會有一定程度之影響。由 23 種植物精油及 5 種脂肪酸鉀鹽中篩選出肉桂葉與椰子油鉀鹽，並發現將兩者以特定比例混合對基腐病菌有加成的抑制效果，故以此進行後續試驗。甘藷盆苗防治試驗中發現，相較於單獨施用，肉桂葉混合椰子油鉀鹽後對基腐病確實可達到較佳的防治效果；此外，施用腐絕、待克利、普克利、菲克利及貝芬菲克利亦可降低疾病嚴重度；然而施用拮抗微生物於甘藷盆苗防治試驗卻未見防治成效。將帶病扦插苗在種植前先浸泡防治，結果顯示腐絕或肉桂葉混合椰子油鉀鹽的處理均可在種植後 40 天及 60 天降低其疾病嚴重度。甘藷塊根防治試驗的結果則顯示，肉桂葉混合椰子油鉀鹽、腐絕、待克利、普克利、貝芬菲克利均可顯著減少甘藷塊根基腐病之疾病嚴重度。總結而言，肉桂混合椰子油鉀鹽確實對甘藷基腐病具有防治潛力。未來可持續觀察氣候因子與基腐病發生之關聯，並探討非農藥資材或化學藥劑於田間防治的施用時機及頻率，以達到更好的防治效果。

關鍵字

甘藷 ； 基腐病菌 ； 非農藥資材 ； 植物精油 ； 脂肪酸鉀鹽 ； 拮抗微生物

並列摘要

Foot rot disease, caused by Phomopsis destruens, is the most important disease of sweet potato in Taiwan. The symptoms include stem rot, leaf yellowing, plant wilt and storage tuber rot. In 2016, two fungicides are officially recommended for controlling this disease. However, due to the growing concern about food safety, pesticide residues and environment sustainability in recent years, reducing the use of synthetic pesticides has become a general trend. Therefore, the aim of this study is to investigate the cultivation type and incidence of foot rot disease in northern Taiwan, and to screen some non-pesticides with potential to control foot rot disease of sweet potato. According to official data, it was a year of bumper harvest for sweet potato in Jinshan and Wanli area in 2016. While the loss of yield caused by foot rot disease was minor in that year. Due to the outbreak of an extremely cold front happened in January in 2016, this study tried to elucidate whether low-temperature could affect the survival of pathogens. The results showed that after treating diseased tissues with 4℃ low temperature for 5 days, isolation rate of the pathogen had reduced to 20%, but could be isolated after 14 days. The conidia germination rate of P. destruens was about 43% after low-temperature treatment for 14 days. Thus, it was assumed that low temperature has important influence on the survival of pathogen. The cinnamon leaf oil (CLO) and the potassium salt of coconut oil (COPS), selected from 23 essential oils and 5 potassium salts of fatty acid (FAPS), were found to have an additive inhibition effect on P. destruens after mixed with a specific ratio, which was used therefore in this study. In the pot assay, results indicated that CLO + COPS can achieve better control effect as compared with control or that applied alone. The fungicides including thiabendazole, difenoconazole, propiconazole, hexaconazole and carbendazim + hexaconazole also showed good control efficacy for foot rot disease. However, the treated antagonistic microorganisms did not show controlling efficacy for foot rot disease. In the dipping therapy assay for diseased seedlings, results revealed that both thiabendazole and CLO + COPS treatments can reduce the disease severity after 40 and 60 days cultivation. In the dipping control assay of sweet potato storage tubers, CLO + COPS, thiabendazole, difenoconazole, propiconazole, and carbendazim + hexaconazole showed significantly decrease of severity of foot rot disease. In conclusion, CLO + COPS does have potential to control foot rot disease. The relationship between climate factors and incidence of foot rot disease should be observed continuously in the future. In order to achieve better control efficacy, the timing and frequency of treatment including non-pesticides and pesticides should also be further studied.

並列關鍵字

sweet potato ； Phomopsis destruens ； non-pesticide ； essential oil ； potassium salts of fatty acids (FAPS) ； antagonistic microorganism

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