Articles

Management of southern corn rootworm and leafhoppers by treating seeds: field assessments in maize second crop in Southern Brazil


Abstract


Maize productivity is highly affected by Diabrotica speciosa and Dalbulus maidis in the second crop seasons in southern Brazil. Thus, this study evaluated the effects of different systemic insecticides tested at recommended doses by seed treatment on the management of these two pest species and assessed the influenceof these treatments on maize yield. For this purpose, we conducted a 2-year fieldexperiments (2015/2016 and 2016/2017) at two locations (Chapecó and Guatambú) in Santa Catarina State, southern Brazil. The experiments were conducted under natural infestation of both pest species, with eight treatments [(Imidacloprid, thiamethoxam, imidacloprid+thiodicarb, fiponil, imidacloprid+bifenthrin, chlorantraniliprole, chlorantraniliprole+clothidian (standard used in industrial seed treatment), and a negative control (without insecticides)]. There were fivereplicates per treatment, totaling 40 experimental units. The results showed that seed treatment do not reduce population density of D. maidis after 21 days of plant emergence and injuries in the maize root system caused by D. speciosa larvae. In addition, insecticides via seed treatment do not affect productivity and crop yield components. Regardless of the location and year, root damage was positively correlated with diameter of the firstinternode and inversely correlated with grain yield. This research suggests that maize seed treatments not always provide economic benefits to farmers, such as pest eductions or yield improvements.

Keywords

Zea mays, neonicotinoids, pyrazoles, Diabrotica speciosa, Dalbulus maidis, IPM

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