Implications of cereal rye cover crop termination timing and residue management on Palmer amaranth (Amaranthus palmeri) and sicklepod (Senna obtusifolia) control in peanut

Abstract

Weed management in peanut primarily relies on intensive herbicide programs. Integrating cereal rye as a cover crop may reduce herbicide input without compromising weed control. Field experiments were conducted to evaluate cereal rye termination management and herbicide programs in peanut. Main plot treatments included a winter fallow control and four cereal rye termination scenarios: (1) early termination 28 days before peanut planting (DBP) with residue rolled flat, (2) early termination 28 DBP with residue left standing, (3) late termination 14 DBP with residue rolled flat, or (4) late termination 14 DBP with residue left standing. Sub-plot treatments consisted of four herbicide programs: (1) preemergence (PRE) plus early postemergence (EPOST) plus mid-postemergence (MPOST) herbicides; (2) PRE plus MPOST herbicides; (3) EPOST plus MPOST herbicides; and (4) a nontreated control. Early cereal rye termination (28 DBP), whether rolled or standing, reduced Palmer amaranth density by 36 to 48% without PRE herbicides and by 36 to 50% when PRE herbicides (fluridone or flumioxazin) were applied. Sicklepod density was unaffected by early termination. In contrast, late termination reduced sicklepod density by 47 to 50% and Palmer amaranth density by 64–86% relative to the winter fallow control at 28 days after PRE application. Across all treatments, cereal rye reduced Palmer amaranth and sicklepod biomass by 63 to 67% and 63 to 65%, respectively, 28 days after MPOST herbicide application. However, standing cereal rye residue reduced peanut yield compared to rolled residue and the winter fallow. Late-terminated, rolled cereal rye residue combined with reduced herbicide programs (PRE plus MPOST or EPOST plus MPOST) provided weed control and yield comparable to the intensive herbicide program (PRE plus EPOST plus MPOST) in winter fallow control. Based on these findings, late-terminated, rolled cereal rye has the potential to reduce herbicide input while maintaining peanut yield and effective weed suppression.