机动弥雾法施用70%吡虫啉水分散粒剂防治小麦蚜虫的雾滴沉积密度与防效的关系

田间采用背负式机动弥雾机对70%吡虫啉水分散粒剂进行喷雾试验,证明若吡虫啉喷雾雾滴在小麦穗部形成一定的沉积密度即可有效防治麦蚜。当70%吡虫啉水分散粒剂用水稀释2 333倍(有效成分300 mg/L),雾滴密度在54,133和280个/cm2条件下,施药7 d后对麦蚜的防治效果分别为83.3% ,88.7%和93.7%;当药剂稀释1 167倍(有效成分600 mg/L),雾滴密度在75,142和291个/cm2条件下,7 d后对麦蚜的防治效果分别为88.1%,94.5%和96.5%。采用背负式机动弥雾机,采用常量150 L/hm2、低浓度(300 mg/L)喷雾时,小麦穗部、旗叶上的雾滴沉积密度分别为177±12,113±8个/cm2,沉积量分别为27.4±6.8,6.6±1.6 ng/cm2,地面流失率为12.8%,7 d后的防治效果为94.0%; 当采用低容量75 L/hm2、高浓度(600 mg/L)喷雾时,小麦穗部、旗叶上的雾滴沉积密度分别为127±13,91±7个/cm2,沉积量分别为29.8±1.2, 6.7±0.6 ng/cm2,地面流失率为10.6%,7 d后的防治效果为93.8%。生产中建议采用吡虫啉低容量75 L/hm2、高浓度600 mg/L喷雾,省工、省水、省时。

Relationship between droplet density and field efficacy when appling imidacloprid 700WG against wheat aphids with knapsack mist-blower

The relationship between wheat aphids field efficacy and imidacloprid concentration,droplet deposition density was studied.Field application of imdacloprid 700WG with knapsack mist-blower showed that certain droplets deposition density on wheat head can effectively control wheat aphids.Seven days after imidacloprid spraying,the field efficacy against wheat aphids were 83.3%,88.7% and 93.7% when droplet deposition density were 54,133 and 280 particle/cm²,respectively at concentration of 300 mg/L;and the field efficacy were 88.1%,94.5% and 96.5% when droplets deposition density were 75,142 and 291 particle/cm²,respectively at concentration of 600 mg/L.When field spraying with knapsack mist-blower at volume of 150 L/ha and 75 L/ha,the droplet deposit density on wheat head,flag leaf were 177±12,113±8 and 127±13,91±7 particle/cm²,respectively;and the run-off rates of spray on field ground surface were 12.8% and 10.6%,respectively.There was no significant difference of spray deposit dosage on wheat head,flag leaf between spraying with low volume of 75 L/ha at 600 mg/L and spraying with volume of 150 L/ha at 300 mg/L;and the field efficacy against wheat aphids were 94.0% and 93.8%,respectively.When applying imdidacloprid against wheat aphids with knapsack mist-blower,low volume of 75 L/ha at high concentration of 600 mg/L was preferred for labor,water and time saving.