Different POST-em Herbicide Programs for Weed Management in Lowland Flooded Rice System in North Macedonia

Abstract

The field experiments were carried out during 2017 and 2018 on commercial rice field in Kochani region to assess different POST-em herbicide programs for weed management in lowland flooded rice system in North Macedonia. In addition, herbicide selectivity and impact on rice grain yield were estimated. POST-em herbicide treatments were used in early-(EPOST-em), mid-(MPOST-em) and late-(LPOST-em) rice growth stages (BBCH 26; 29 and 32-34, respectively). Weed control varied among herbicide treatments, herbicide programs, and weeks after treatments (WAT). All herbicides applied EPOST-em controlled Echinochloa crus-galli (ECHCG) and Scirpus maritumus (SCMA) 91-100%. At MPOST-em treatment, herbicides showed control of ECHCG between 93 and 97%. However, all herbicides applied LPOST-em controlled ECHCG 79-88%. SCMA control was less than 88 and 85% with MPOST-em and LPOST-em treatments, respectively, perhaps as a consequence of progressive growth stage of SCMA (BBCH 40). Control level of Cyperus rotundus (CYPRO) and Heteranthera reniformis (HETRE) was high in all POST-em treatments (between 90-100%, and 95-100%, respectively). EPOST-em and MPOST-em application of any herbicide resulted no phytotoxicity to rice plants. LPOST-em treatments caused rice phytotoxicity by cyhalofop-butyl + penoxsulam, cyhalofop-buthyl + bentazon, and profoxidim + bentazon which were ranged from 8-20%. Unlike rice yield at LPOST-em treatments was 6235 kg ha-1, all EPOST-em and MPOST-em used herbicides has impact in rice yield 6685 and 6610 kg ha-1, respectively which, but there were no statistically significant differences with the weed free control 6710 kg ha-1.