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.

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