Rhizoctonia solani와 Pythium ultimum의 접종 농도가 etridiazole과 thiophanate-methyl 합제의 모잘록병 방제 효과에 미치는 영향

This study was performed to investigate the inhibiting activity of etridiazole and thiophanate-mthyl on mycelial growth of Rhizoctonia solani and Pythium ultimum and the effect of inoculum density of each pathogen on the control efficacy of the mixture of etridiazole and thiophanate-methyl in a seedling assay test. In mycelial growth inhibition test, $EC_{50}$ values of etridiazole and thiophanate-methyl against R. solani were 15.87 and 9.34 ${\mu}g\;mL^{-1}$, while those were 0.2 and more than $500\;{\mu}g\;mL^{-1}$ against P. ultimum, respectively. Controlling activity of the mixture of etridiazole and thiophanate-methyl against damping-off of pepper and cucumber, caused by R. solani and P. ultimum was tested in a greenhouse. With the inoculation of R. solani, disease incidences of seedling in pepper were 73% and 95% at 0.5% and 1.0% of inoculum concentration, while in cucumber those were 55% and 62% at 1.0% and 2.0%. When P. ultimum was inoculated into soil by 2.0% of inoculum concentration, those in pepper and cucumber were 66.7% and 96.8%, respectively. The efficacy of the mixture was somehow affected by the concentration of R. solani. While each control value of the mixture was 94.4% and 90.7% in pepper and cucumber at low inoculum concentration (0.05%), the efficacy of the fungicide decreased in pepper and cucumber by 70.7% and 72.9% at high concentration of R. solani (0.1% in pepper and 0.5% in cucumber). However, the control value of the mixture was 100% in pepper and cucumber, irrespective of the inoculum concentration of P. ultimum, however, the increase of inoculum concentration in soil did not result in the decrease of the fungicide efficacy. 모잘록병균인 Rhizoctonia solani와 Pythium ultimum에 대한 etridiazole과 thiophanate-methyl의 균사 생장 억제 효과와, 각 병원균의 토양 접종 농도가 etridiazole과 thiophanate-methyl 합제의 고추와 오이 모잘록병에 대한 방제 효과에 미치는 영향을 조사하였다. R. solani와 P. ultimum의 균사 생장 억제에 대한 etridiazole의 $EC_{50}$값은 각각 $15.87\;{\mu}g\;mL^{-1}$과 $0.20\;{\mu}g\;mL^{-1}$이었지만, thiophanate-methyl의 $EC_{50}$값은 R. solani에 대해서$9.34\;{\mu}g\;mL^{-1}$이었고, P. ultimum에 대해서는 $500\;{\mu}g\;mL^{-1}$ 이상이었다. 온실에서 실시한 유묘 검정 결과, R. solani와 P. ultimum의 접종원 농도가 높아지면 고추와 오이에서의 병 발생도 상승하였다. R. solani의 토양 접종 농도가 0.1%(w/v)이었을 때 파종 14일 후의 고추 발병주율은 41%이었으며, 0.5%와 1.0%로 접종하였을 때는 73%와 95%까지 상승하였다. 오이에서는 접종원 농도가 1.0과 2.0%일 때, 각각 55%와 62%의 발병주율을 보였다. P. ultimum에 의한 유묘에서의 발병주율은 고추보다 오이에서 더 높게 나타났는데, 2%의 농도로 병원균을 접종하였을 때, 고추와 오이의 발병주율은 66.7%와 96.8%이었다. R. solani의 경우 혼합제의 효과는 병원균의 접종 농도에 따라서 변화하였는데, 접종 농도가 0.