The Toxicity Determination And Field Application Of Tebuconazole50%Nano Spx On The Alternaria Alternate F.SP. Mali

First, fungitoxicity of tebuconazole50%nano spx against Alternaria alternata f.sp. maliwas measured by mycelial growth rate method in this study. On the basis of toxicitydetermination, the field efficacy of tebuconazole50%nano spx controlling apple leaf spotwas evaluated. The main results of research are as follows:1、The toxicity determination results showed that，the toxicity of tebuconazole50%nano spx was the strongest to A. alternata f.sp. mali with the EC50value of6.23μg/mL.In addition, the toxicity of tebuconazole50%SC was lower to A. alternata f.sp. maliwith the EC50value of10.34μg/mL.2、It was showed by field investigation and control experiment that when theconcentration is85～125mg/kg, the control effect of tebuconazole50%nano spx onapple leaf spot was79.21%～88.51%in vernal shoot retardation period and was81.12%～91.03%in leaf expansion period in the first experimental field。When theconcentration is125mg/kg, compared with control pesticide tebuconazole50%SC,thetreatment effect increased9.15%in vernal shoot retardation period，the treatment effectincreased10.39%in leaf expansion period。3、It was showed by field investigation and control experiment that when theconcentration is85～125mg/kg, the control effect of tebuconazole50%nano spx onapple leaf spot was80.40%～89.10%in vernal shoot retardation period and was81.19%～90.56%in leaf expansion period in the second experimental field。When theconcentration is125mg/kg, compared with control pesticide tebuconazole50%SC,thetreatment effect increased8.15%in vernal shoot retardation period，the treatment effectincreased9.8%in leaf expansion period。4、The recommended concentration of tebuconazole50%nano spx against A. alternataf.sp. mali were85～125mg/kg.5、The results of safety assessment showed that no negative effects of tebuconazole50%ano spx on apple trees were found.