Side-band application of systemic granular pesticides for the control of aphids and potato leafroll virus

Abstract

In six replicated trials over 3 years, carbamoyloxime granular pesticides, applied in-furrow at planting or 4–7 weeks later as side-bands incorporated into the ridges of the emerging crop, were tested for the control of aphids and potato leafroll virus (PLRV) in seed potato crops in Scotland. Aldicarv applied at planting either at ‘high’ ( 8 · 6 g a.i. 100 m ) or ‘low’ ( 4 · 3 g a.i. 100 m ) rates controlled aphids until late July or mid-August. In-furrow treatment with thiofanox ( 5 · 6 g a.i. 100 m ) gave longer control of aphids than aldicarb, but at 2 · 8 g a.i. 100 m , in-furrow or as side-bands, it was inferior to aldicarb. Side-bands of aldicarb at low rates controlled the peach-potato aphid ( Myzus persicae) longer than low-rate in-furrow treatment in trials in eastern Scotland but not in Ayrshire. Plants infected with PLRV were grown in each plot to provide local sources of infection. In most trials, in-furrow application of aldicarb at the high rate gave the best control of PLRV but aldicarb applied in-furrow at the low rate was almost as effective. Side-band treatments were generally less effective than the equivalent in-furrow treatments, although in one trial where aphids did not colonize the crop until mid-July, side-band application of aldicarb was as effective as in-furrow treatment. In trials in Ayrshire all the treatments were less effective in controlling virus spread than in similar trials in eastern Scotland, possibly because of the prevalence of insecticide-resistant M. persicae in that area. Applying insecticides as side-bands had no deleterious effect on yield, but the technique was too unreliable to replace in-furrow application for the control of PLRV, and would be difficult to integrate with present cultivation methods.