The effect of seed treatments on wireworm (Elateridae) performance, damages and yield traits of sunflower (helianthus annuus l.)

Abstract

© 2019, University of Zagreb - Faculty of Agriculture. All rights reserved. Sunflower seed treatments are inevitable measure that ensures protection from soil-dwelling insects and pathogens at the first stages of plant development. Due to the ban of neonicotinoid based insecticides for the sunflower seed treatments, new registered preparations are put to test. The aim of this work was to assess the efficacy of currently registered insecticides against the wireworms (observed in field emergence and percent of damaged plants) and their effect on yield traits (yield, oil content and 1,000-seed weight) of the sunflower hybrids (Sumo 2 OR, Oliva and Novak) in comparison to previously used neonicotinoids. Seeds were treated with different pesticidal combinations: metalaxyl-m, metalaxyl-m + bifenthrine, metalaxyl-m + thiacloprid, metalaxyl-m + thiametoxam, and metalaxyl-m + imidacloprid. Two-way ANOVA and Duncan’s multiple range tests were performed. Field emergence was not influenced by the treatment. Sumo 2 OR and Oliva emergence did not differ significantly among the treatments (78.3-88.3%; 83.0-91.3%, respectively), but for Novak it was significantly lower (79.3%) when treated with metalaxyl-m. The lowest percent of damaged plants was in the treatment with metalaxyl-m + thiametoxam (1.1-2.4%). However, it did not differ significantly among other treatments (2.4-3.9%), regardless on the hybrid. Novak had the highest average yield (3,938.1 kg/ha), followed by Sumo 2 OR (3,566.1 kg/ha), and Oliva (3,199.8 kg/ha), regardless on the applied seed treatments. The highest 1,000-seed weight was measured for Oliva. Given indicates that currently registered insecticides for the seed treatment of sunflower, such as Sonido and Semafor, can be adequate substitute to the banned neonicotinoids like Cruiser and Gaucho.