Influence of planting date, row spacing, and reduced herbicide inputs on peanut canopy and sicklepod growth

Sicklepod [Senna obtusifolia (L.)] is one of the most problematic weed species for peanut production in the southeastern USA. A two-year study was conducted to evaluate the influence of peanut planting date and row spacing on sicklepod growth. Planting date was the main plot factor with early (early May), mid- (mid-May), or late (early June) timings. Row spacing was the subplot factor with single row and twin rows at 13, 18, or 23 cm. For minimal herbicide use, pendimethalin was applied at peanut planting and 2,4-DB was applied at 6 wk after planting. Peanut on twin rows at 18 and 23 cm achieved canopy closure 2 wk earlier than the single or the 13-cm twin-row. In 2019, sicklepod height was similar across all planting dates, while in 2020 height decreased in the order of late > mid > early planting. Sicklepod biomass in early planting was greater compared with mid and late planting in 2019, whereas biomass was greater in late planting compared with early and mid-planting in 2020. Peanut yield was 50% greater in early and mid-planting compared with late planting in 2019, while yield was 18% lower in the single row compared with the twin rows in 2020. The differences between the two years were attributed to greater humidity and heavy rainfall during 2020 (137 cm) compared with the 2019 (77 cm) season. We conclude that peanut planted on 18- or 23-cm twin rows during the mid-planting date has the potential to maintain yield and suppress sicklepod.

Automated summary

The study showed that planting peanut during the mid-season on twin rows with row spacing of 18 or 23 cm can effectively suppress sicklepod growth and maintain peanut yield.