A Casual Agent and Control of Lily Seedling Blight

• Main Authors: Wu, Rey-Shung, 吳瑞香
• Other Authors: Huanf Jenn-Wen
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/30923171460586758499

碩士 === 國立中興大學 === 植物病理學系 === 85 === In a survey of fungi associated with blight of lily seedlings grown incentral Taiwan, 151 isolates including Fusarium proliferatum, F.oxysporum, F. solani, F. ventricosum, Pythium spp. and Rhizoctoniasolani were obtained. F. proliferatum was consistently isolated fromdiseased seedlings with 80.1% frequency of appearing on 2% water agaras well as Nash PCNB medium. Pathogenicity of F. proliferatum wasdetermined on lily seedlings(cv. Casablanca). The bulblets of lilywere dipped in the spore suspension(1.3 × 106 CFU/ml) of the fungusfor 1 min. and planted in a sterilized medium. Damping- off, yellowingand wilting symptoms of lily seedlings were observed three weeks afterinoculation. The fungus was reisolated from diseased tissues ofinoculated plants. Koch's postulates were completed and indicated thatthe tested fungus was the causal agent. Temperature was able tosignificantly affect the occurrence of lily seedling blight. In growthchambers, the disease severity was markedly increased with incrementof temperatures from 24 to 36 ℃. Lily bulblet scales were used tobait F. proliferatum from eight culture media. Approximately 80% ofscales buried in FF-007C, FF-007G and TSS-01 media and 20-30% ofscales in TSC-102, TSC-103 and FF-006 media were colonized by F.proliferatum. However, the fungus was not recovered from TSC-101 andTSS-02 media. Six fungicides were evaluated for their effect oncontrol of lily seedling blight caused by F. proliferatum. Amongthose, prochloraz at 400 ug/ml, sporgon at 250 ug/ml, and prochlorazat 400 ug/ml mixed with benomyl at 500 ug/ml were the most effectiveto reduce the disease severity of lily seedling blight by 58-92% andbulblet rot by 81-88% as compared with none treatment as a control ingreenhouse tests. The same effectiveness of prochloraz and sporgon onthe disease control was also observed in the field tests at TaiwanSeed Improvement Propagation Station in Central Taiwan. Antagonists ofF. proliferatum were isolated from culture media, healthy lilyseedlings and seeds of alfafa and radish. Nonpathogenic F. oxysporumisolates FO-401 & FO-403, Streptomyces spp. isolates PMS-101, 104 &106, S. griseoviridis isolates PMS-109, Bacillus spp. isolates PMB-101, 102 & 103, B. thermoglucosidasius isolate PMB-106 and florescentPseudomonads isolates PMP-001, 002 & 004 were able to significantlyreduce lily seedling blight caused by the pathogen in the greenhouseand screenhouse. Bulblets of lily were pre-treatment with sporgon anda sporgon- tolerant anagonist PMS-101 or PMB-106 and planted in themedium infested with F. proliferatum in the greenhouse. After sevenweeks, the combination method was able to protect 20-50% of lilyseedlings from infection by F. proliferatum. A field test indicatedthat bulblets treated with sporgon at 400 ppm and planted in theinfested medium pre-inoculated with B. thermoglucosidasius PMB-106showed 20% reduction of lily seedling blight and promoted growth ofthe seedlings.