Comparative Efficacy, Cost-Efficiency, and Phytotoxicity of Premium and Generic GlufosinateAmmonium Formulations for Paspalum conjugatum Control

Abstract

This study compared weed-control efficacy, biomass responses, phytotoxicity, and cost-efficiency of premium and generic glufosinate-ammonium commercial programmes for Paspalum conjugatum under local conditions. A randomised complete block design with three independent blocks was used. Five treatments were evaluated: untreated control; premium programme (Tepat®, 5.66% w/w glufosinate-ammonium) at 6 and 12 L/ha; and generic programme (Vista 15, 13.5% w/w glufosinate-ammonium) at 3 and 6 L/ha. For weed assessments, three tray subsamples within each treatment-by-block unit were averaged before inferential analysis (n = 3 independent block means). Equal active-ingredient doses could not be verified because product-density data were unavailable; therefore, comparisons refer to commercial application programmes rather than equivalent active-ingredient doses. Weed-control efficacy was assessed for six weeks, fresh and dry biomass at 42 days after treatment, and Brassica juncea served as a sensitive indicator of off-target phytotoxicity. All herbicide programmes achieved approximately 97-98% weed control at three weeks and significantly reduced biomass relative to the untreated control. No statistically significant difference in final weed-control performance was detected between premium and generic programmes; this should not be interpreted as biological equivalence. All herbicide programmes caused severe phytotoxicity to B. juncea by day 7. Partial-budgeting analysis showed that generic programmes reduced treatment costs by RM60-RM120/ha, equivalent to estimated annual savings of RM180,000-RM360,000 for 3,000 ha. These results support considering biological performance, crop safety, and treatment cost when selecting glufosinateammonium programmes.