Abstract
Among 34 isolates of Colletotrichum spp., 20 from red pepper and 14 from apple, only one isolate 2001-45 was identified as the isolate resistant to sterol biosynthesis inhibiting fungicides. EC$_{50}$ values of the isolate 2001-45 were 153.5, 42.7, 34.0, and 17.1 $\mu\textrm{g}$/ml for myclobutanil, tebuconazole, hexaconazole and nuarimol, respectively, The resistance factor of the isolate 2001-45 against the other isolate 2001-44 to 4 above fungicides was ranged from 17 to 57. However, EC$_{50}$ value of the 2001-45 for prochloraz was 0.07 $\mu\textrm{g}$/ml, which was lower than those of the 2001-44 and the isolate JC24. For the fitness test of the 2001-45, mycelial growth, sporulation on PDA and pathogenicity on fruits were investigated. No difference in mycelial growth was found between 2001-45 and 2001-44, but great difference in sporulation. No symptom was developed by 2001-45 even by wound inoculation of pepper fruit. Therefore, this study indicated that the isolate 2001-45 was inferior to the other isolates in the fitness, although the isolate 2001-45 was highly resistant to sterol biosynthesis inhibiting fungicides.
고추와 사과에서 분리한 20개와 14개의 탄저병균 중에서 2001-45가 스테롤 생합성을 저해하는 살균제에 대하여 저항성 균주로 판명되었다. 2001-45는 myclobutanil, tebuconazole, hexaconazole, nuarimol 등에 대하여 153.5, 42.7, 34.0, 17.1 $\mu\textrm{g}$/ml로, 실험에 사용한 다른 탄저병균들 보다 높은 EC$_{50}$ 값을 보이며, 서로간에 교차 저항성을 나타냈다. 하지만 prochloraz(스테를 생합성 저해 살균제)에 대한 EC$_{50}$ 값은 0.07 $\mu\textrm{g}$/ml로, 감수성균인 2001-44와 JC24 보다도 감수성이 높았다. 20, 25, 3$0^{\circ}C$에서 스테롤 생합성 저해 살균제에 대하여 저항성인 2001-45의 균사 생장은 2001-44와 비슷하였으며, 또 다른 감수성인 JC24보다는 빨랐다. 그러나 PDA상에서의 포자 형성 능력과 고추열매에 대한 병원성은 JC24보다 현저하게 떨어졌다.