草莓園鐮孢菌之檢測及萎凋病之研究

The Study on Strawberry Wilt Disease and Detection of Fusarium Pathogen in the Orchards

呂柏寬(Po-Kuan Lu)

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(2013年)

https://doi.org/10.6342/NTU.2013.01473

摘要

草莓Fragaria ananassa屬薔薇科 (Rosaceae) 多年生草本經濟作物，是深受消費者喜愛的多年生草本溫帶水果。近年來在苗栗大湖地區已發生草莓幼苗大量死亡萎凋之嚴重疾病，田間亦可發現植株生長不良、具大小葉之萎凋病罹病株。故能造成草莓植株萎凋的病害除炭疽病、疫病及腐黴病菌外，已增加由Fusarium oxysporum 造成之草莓萎凋病。
草莓萎凋病為土傳性病害，對於草莓產業具嚴重、潛在的威脅，本研究之目的首先在求建立一田間檢測之技術，故嘗試利用選擇性培養基配合菌落特性，建立鑑別病原菌之快速方法，並利用於台灣北部地區草莓園田間植株及土壤之檢測，結果發現草莓萎凋病菌培養於K2培養基上會呈現輻射毛刷狀菌落邊緣，此乃具有鑑別之能力，而在田間檢測僅於大湖三號採集地玉安，於草莓之病根及冠部可檢測出草莓萎凋病菌，而各土壤均未檢測出此一病原。
因為過去本病害之病原性檢測需時甚久，懷疑需有夏季之高溫才能促進此病害之發生，故利用不同處理方式，配合高溫誘病生長栽培架，進行病原性檢定，發現以浸根接種之方式經高溫誘病，能加快病勢之發展，而以菌絲塊靠接接種亦可造成發病但發病率較低。水耕處理則不利於病原菌之生長、繁殖及發病。
本研究亦探究本病菌相關之生理特性，發現草莓萎凋病病原菌在25至30℃、酸鹼度6-9之間可生長良好，光照可促進大孢子產生。
目前此病害並無完善之防治策略，研究中嘗試篩選緊急用化學藥劑來進行防治，初步已篩選出53%腐絕快得寧和30%賽福座可濕性粉劑，此二藥劑於培養基測試結果中具有最佳之菌絲抑制率。
本研究發現本病之侵染仍遺留甚多不明之處，如根及冠部之內部病徵常不明顯，可檢測到之帶菌量極低，其在田間之殘存、傳播、發病生態及其與其他炭疽病或疫病菌間之關係仍待更多之研究。

關鍵字

草莓 ； 萎凋病 ； 尖鐮孢菌 ； 檢測 ； 殺菌劑

並列摘要

Strawberry, Fragaria ananassa，is a very important fruit crop and is a perennial herbaceous plants. In recent years, a new wilt disease of strawberry was found in Miaoli country, Taiwan. The wilt strawberry grew poorly and showed uneven growth leaves in the field. Because Colletotrichum spp., Phytophthroa spp. and Pythium spp. can also cause the wilt or dead of strawberry, the role of Fusarium pathogen needs to be elucidated.
The strawberry wilt disease is a soilborne disease with a great loss potential for strawberry industry. This research is aimed to elucidate the role of suspect Fusarium oxysporum associated with this disease and to develop rapid detecting techniques for this pathogen. The Fusarium selective media were screened and compared for the ability to differentially identify the pathogen with cultural characteristic.
The Result showed that on K2 medium strawberry fusarial wilt pathogen developed a distinguished radiated colony with brush-like edge. Using this technique, we surveyed 8 field sites and detected many diseased seedlings together with soil. Results showed that this could only be detected in diseased crown tissue and residual roots from a strawberry orchard in Dahu, Miaoli country. No pathogenic Fusarium oxysporum was detected from the roots and soil collected from other region.
As preview reports showed that the pathogenicity test of strawberry wilt pathogen takes over two months, we designed a hot growth shelter for enhancing the wilt disease development. Three inoculation experiments were then conducted to associate the pathogen detected by the selective medium and the wilt disease. The results showed that dipping the root in conidial suspension followed by incubation in hot growth shelter can induce the disease in 2 weeks. When inoculated with a mycelia disc in the stem, only some seedlings developed symptoms and disease is not so severe. Inoculation in hydroponic system showed that no strawberry developed the symptom.
To understand the physiological characteristics of the pathogenic Fusarium oxysporum, we conducted some physiological studies. Results showed that the pathogen grows normally at between 25 to 30℃, and at pH from 6 to 9. Illuminating the colony can increase the production of macroconidia of this Fusarium pathogen.
Currently, no perfect control strategy has been established for strawberry wilt disease. Therefore we have selected and treated some chemical fungicide for controlling this disease. Results showed that both 53% thiabendazole + oxine-copper and 30% triflumizole wettable powder can inhibit the mycelial growth of this pathogen on PDA.
All the above results suggested that at present the detail infection process of this disease is still not clear. The internal symptoms on crown and root are not obvious. The pathogen density in the diseased strawberry are found to be very low. Their survival, transmission and disease ecology are not clear. The correlation with other pathogen including anthracnose, and phytophthora are not known. These indicate that a lot of research needed to be done in the future.

並列關鍵字

Strawberry ； wilt disease ； Fusarium oxysporum ； detection ； fungicide

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