Development of assay method for the activities of new compounds, and the effect of several fungicides against spore germination, adhesion, and myceial growth of Colletotrichum sp. causing red pepper anthracnose

고추 탄저병균의 포자 발아와 부착, 균사 생장에 미치는 화합물의 활성 검정법 확립 및 살균제의 효과

  • Kim, Jae-Jeung (Department of Agricultural Biology, Chungbuk National University) ;
  • Kim, Joon-Tae (Department of Agricultural Biology, Chungbuk National University) ;
  • Park, Sung-Woo (Department of Agricultural Biology, Chungbuk National University) ;
  • Park, Eun-Suk (Department of Agricultural Biology, Chungbuk National University) ;
  • Kim, Heung-Tae (Department of Agricultural Biology, Chungbuk National University)
  • 김재정 (충북대학교 농과대학 농생물학과) ;
  • 김준태 (충북대학교 농과대학 농생물학과) ;
  • 박성우 (충북대학교 농과대학 농생물학과) ;
  • 박은숙 (충북대학교 농과대학 농생물학과) ;
  • 김흥태 (충북대학교 농과대학 농생물학과)
  • Published : 2003.09.30

Abstract

With microtiter plate, the assay method was developed for detecting the fungicidal activity of new compounds against spore germination, spore adhesion and mycelial growth of Colletotrichum sp. JC24 cal1Sing red pepper anthracnose. Also, the effects of some commercialized fungicides on fungal development like above mentioned were investigated by measuring the optical density of mycelia grown into wells of microtiter plate. For the standardization of assay method, some factors, such as the treatment of MTT and/or propanol, inodulum density and incubation period, affecting on mycelial optical density were investigated. For obtaining precise and consistent mycelial optical density, it was necessary the treatment of MTT for 12 hrs and propanol for 1 hr. inoculum density adjusted to $1\times10^5$ spores/mL and incubation period for 36 hrs at $25^{\circ}C$. For fungicidal activities, 6 protective fungicides, 6 ones inhibiting sterol biosynthesis, and one inhibiting respiration were used in this study. While mancozeb, chlorothalonil and dithianon among 6 protective fungicides inhibited strongly spore germination, adhesion, and mycelial growth at $6.25{\mu}g/mL$, propineb, iminoctadine and fluazinam inhibited intermediately spore germination and mycelial growth at $100{\mu}g/mL$. Washing above 3 fungicides with new PD broth, their activity against spore adhesion decreased. With hexaconazole, tebuconazole and myclobutanil, the tendency of the activity against fungal differentiation of the early infection stage was similar to the latter group of protective fungicides, showing the decrease of the inhibitory activity against spore adhesion by washing 2 hrs after incubation. However, kresoxim-methyl inhibited spore adhesion distinctly, depending on the applied concentrations. Based on these results, it might be able to assess the fungicidal activity of many compounds against spore germination, adhesion and mycelial growth by the use of microtiter plate in vitro. Using the assay developed in this report, it was possible to investigate the inhibitory activity of some commercialized fungicides, too.

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