四氟醚唑对黄瓜的安全性及其对黄瓜白粉病的防治效果

为明确四氟醚唑对黄瓜植株的安全性,采用浸种及茎叶喷雾处理的方法测定其对不同生长时期黄瓜植株的影响,采用子叶保湿培养法测定白粉病菌对其敏感性,并在田间进行防治白粉病的药效试验,综合评价了四氟醚唑对黄瓜白粉病的效果。浸种处理后,黄瓜子叶上白粉病发病率明显降低,对黄瓜株高和根长的抑制率、茎周增长率及叶绿素含量增加率与己唑醇相比均较低;发芽期及幼苗期的黄瓜植株使用四氟醚唑处理,新生节间均出现轻微的抑制伸长现象;4％四氟醚唑水乳剂对黄瓜白粉病菌的EC50为0．8146mg／L,敏感毒力高于50％醚菌酯水分散粒剂;田间间隔期10天喷雾,在末次药后7天对黄瓜白粉病的防治效果为76．02％～85．77％,与5％己唑醇水乳剂防效相当,明显高于50％醚菌酯水分散粒剂的防效。表明四氟醚唑对黄瓜生长安全且用药间隔期长,是防治白粉病的高效轮换药剂。     

四氟醚唑在草莓和土壤中的残留动态研究

研究了杀菌剂四氟醚唑的残留分析方法及其在草莓和土壤中的消解动态和最终残留量。草莓经丙酮提取抽滤后,加入饱和醋酸铅和氯化钠水溶液利用共沉淀法除去杂质,再经液液分配及活性炭柱净化、浓缩、定容后,用带ECD检测器的气相色谱进行测定。四氟醚唑的最低检出量为0.03 ng,在草莓和土壤中的最低检出浓度均为0.02 mg/kg,在草莓和土壤中的平均回收率为95.9% ~97.5%,变异系数1.5% ~2.8%,符合残留分析要求。用该方法测定了四氟醚唑在草莓和土壤中的消解动态以及最终残留量,结果表明:四氟醚唑在草莓上的降解速度较快,半衰期为4.2 d;在土壤中降解速度稍慢,半衰期为15.4 d,施药后7 d四氟醚唑的消解达到80%以上。     

四氟醚唑4%水乳剂气相色谱分析

采用气相色谱法对四氟醚唑水乳剂进行定量分析,用rtx-50,30.0m×0.53mm×1.00μm石英毛细管柱和氢火焰离子检测器,以邻苯二甲酸二正戊酯为内标。结果表明四氟醚唑的线性相关系数为0.999 9;标准偏差为0.024;变异系数为0.59%;平均回收率为99.91%。     

液相色谱-质谱联用法测定水-沉积物系统中四氟醚唑的残留量

建立了水-沉积物系统中四氟醚唑的液相色谱-质谱联用(LC-MS/MS)测定方法。沉积物样品依次经V(丙酮)∶V(水)=9∶1混合提取和二氯甲烷萃取后,中性氧化铝与弗罗里硅土层析柱净化,用LC-MS/MS测定;水样经二氯甲烷萃取后直接用LC-MS/MS测定。结果表明:在0.5~5μg/L或0.5~5μg/kg添加水平下,四氟醚唑在水中的平均回收率为89%~98%,相对标准偏差(RSD)为1.8%~13%,在沉积物中的平均回收率为97%~103%,RSD为6.3%~11%。该方法中四氟醚唑的最小检出量为2.0 pg,四氟醚唑在水中最低检测浓度(LOQ)为0.5μg/L,在沉积物中的LOQ为0.5μg/kg。该方法选择性好、灵敏度高、重现性好、基质干扰小,适用于水-沉积物系统中四氟醚唑残留的检测。     

4%四氟醚唑水乳剂防治黄瓜白粉病田间药效试验

为了防治黄瓜白粉病,研究以4%四氟醚唑水乳剂(150g·hm-2、112.5g·hm-2、75g·hm-2)进行田间药效试验,对照药剂为40%氟硅唑乳油(75g·hm-2)。结果表明:4%四氟醚唑水乳剂按150g·hm-2、112.5g·hm-2、75g·hm-2施药后的防效分别为84.59%、76.18%、70.51%,而对照防效为68.27%。因此,4%四氟醚唑水乳剂是防治黄瓜白粉病的理想药剂。     

Degradation kinetics and safety evaluation of tetraconazole and difenoconazole residues in grape

BACKGROUND: Tetraconazole and difenoconazole are triazole fungicides with proven bioefficacy against grapevine powdery mildew disease. In the present work, the authors explored the residue dynamics of these two compounds in grapes and determined their preharvest intervals (PHIs) corresponding to multiple field applications at recommended and double rates considering the most critical use pattern in Indian viticulture. A confirmatory residue analysis method was validated for trace-level determination of both the compounds. RESULTS: Dissipation of both the fungicides followed non-linear two-compartment first + first-order rate kinetics. Tetraconazole and difenoconazole dissipated with PHIs of 12.5 and 25.5 days at recommended rates and of 28.5 and 38.5 days at double application rates respectively. On all the sampling days, the residues were below the maximum permissible intake, indicating consumer safety. The residues in the grape samples drawn from the farms where these two fungicides were applied, maintaining the above PHIs, were below their respective MRLs. CONCLUSION: The rate of degradation of tetraconazole was faster than that of difenoconazole. Thus, the growers will have the choice of using these new chemicals for the management of powdery mildews in succession, difenoconazole at early growth stages, followed by tetraconazole during the last month before harvest. The recommendations of PHIs proved to be effective in minimizing residues in farm grape samples. Thus, this work is of high significance to the grape industry of India, and will support the registration of these new fungicides for effective management of powdery mildews with minimum residue problems.