4种剂型噻虫胺对柑橘木虱的田间防治效果

2018年—2019年,采用田间小区试验评价了噻虫胺4种剂型(30%悬浮剂、18%包埋颗粒剂、13.5%壳聚糖微球和0.5%颗粒剂)及2种施用方式(喷雾和沟施)对柑橘木虱的防治效果。结果表明:叶面喷施30%噻虫胺悬浮剂60 mg/kg处理对幼年树及成年树上柑橘木虱的控制效果好且持效期约30 d,而药后46~96 d的防治效果大幅下降,难以控制其为害。在幼年树根部周围拌毒土沟施时,噻虫胺18%包埋颗粒剂和13.5%壳聚糖微球0.1~0.2 g/株处理对柑橘木虱的控制效果较好,且持效期长达96 d;0.5%噻虫胺颗粒剂0.1 g/株处理对柑橘木虱的效果好且持效期达46 d,而药后66~96 d的防治效果下降明显,难以控制其为害;在0.1 g/株剂量下,0.5%噻虫胺颗粒剂药后7~30 d的效果最好、18%包埋颗粒剂次之、13.5%壳聚糖微球稍差,而18%包埋颗粒剂药后46~96 d的效果最佳、13.5%壳聚糖微球次之、0.5%颗粒剂稍差。在成年树根部周围沟施时,噻虫胺18%包埋颗粒剂、13.5%壳聚糖微球0.6~0.8 g/株处理对柑橘木虱的控制效果好且持效期长达89 d,而0.5%噻虫胺颗粒剂0.2 g/株处理的效果较好且持效期长达89 d;在0.2 g/株剂量下,不同剂型噻虫胺对柑橘木虱的防效差异与幼年树基本一致。此外,当剂型、剂量及施用方式均相同时,噻虫胺对柑橘木虱的控制作用略低于噻虫嗪。综上所述,在柑橘生产实践中,若田间柑橘木虱发生量大,应喷施1次30%噻虫胺悬浮剂60 mg/kg;为有效控制幼年树柑橘木虱为害,应于初发期拌毒土沟施1次,使用药剂为18%噻虫胺包埋颗粒剂,用量为0.2 g/株;针对成年树柑橘木虱,则需将其用量增至0.6 g/株。

Control efficacy of clothianidin with four formulations against the Asian citrus psyllid, Diaphorina citri under field conditions

Field plot experiments were conducted to evaluate control efficacy of clothianidin with four formulations including 30% suspension concentrate (SC), 18% embedded granules (EGr), 13.5% chitosan microspheres (CsMs) and 0.5% granule (GR) using two application methods including foliar spray and furrow application against the Asian citrus psyllid, Diaphorina citri Kuwayama on citrus trees in 2018-2019. The results showed that a single foliar spray of clothianidin 30% SC at a dosage of 60 mg/kg could obviously control D. citri on young and mature trees within 30 days, but its control efficacy was significantly reduced 46-96 days after treatment, and it had difficultly in controlling the pest. Good control efficacies of clothianidin 18% EGr and 13.5% CsMs at dosages of 0.1-0.2 g/tree against D. citri could be achieved within 96 days after furrow application mixed with poisonous soil around the roots of the young tree. This pest was obviously controlled by clothianidin 0.5% GR at a dosage of 0.1 g/tree within 46 days, but it was difficult to control 66-96 days after furrow application. At the dosage of 0.1 g/tree, 7-30 days after furrow application, the control efficacies of clothianidin 0.5% GR were the highest, followed by 18% EGr, and those of 13.5% CsMs were slightly lower, 46-96 days after furrow application, the control efficacies of 18% EGr were the highest, followed by 13.5% CsMs, and those of 0.5% GR were slightly lower. As for the mature trees, clothianidin 18% EGr and 13.5% CsMs at dosages of 0.6-0.8 g/tree could effectively control D.citri, and the better control efficacies of clothianidin 0.5% GR at a dosage of 0.2 g/tree were achieved 89 days after furrow application. At the dosage of 0.2 g/tree, the differences of control efficacies of clothianidin among 18% EGr, 13.5% CsMs and 0.5% GR on mature trees were similar with those on young trees. Additionally, if the application formulation, dosage and method were the same, the control efficacies of clothianidin were slightly lower than those of thiamethoxam on young and mature trees. In summary, these results suggested that a single foliar spray application of clothianidin 30% SC at a dosage of 60 mg/kg could be recommended to control D.citri at the infestation peak in the field. One-time furrow application mixed with poisonous soil of clothianidin 18% EGr at a dosage of 0.2 g/tree was applied in order to effectively control D.citri during the initial period of infestation on young citrus trees, while its dosage should be added to 0.6 g/tree on mature citrus trees.