Weed management in turmeric

Abstract

Pre-emergence metribuzin 0.7 kg/ha, pendimethalin 1.0 kg/ha and atrazine 0.75 kg/ha each followed by i) hand weeding (HW) (45 and 75 DAP, days after planting), ii) fenoxaprop 67 g/ha + metsulfuron-methyl 4 g/ha (45 DAP) and iii) mulch + HW (75 DAP); pre-emergence oxyflourfen 0.3 kg/ha and oxadiargyl 0.25 kg/ha and post-emergence glyphosate 1.23 and 1.85 kg/ha (25 DAP) each followed by HW (45 and 75 DAP); HW (25, 45 and 75 DAP) and untreated control were evaluated at Palampur during 2014, 2015 and 2016 to develop an effective weed management strategy in turmeric for mid hill conditions of Himachal Pradesh. Treatments constituting fenoxaprop + metsulfuron-methyl were phyto-toxic resulting in poor turmeric crop canopy formation thereby more growth of Ageratum sp. and lower plant height, plant stand, daughter corms/mother corm, rhizome yield and economics. Other weed control treatments were effective in controlling Echinochloa colona and other grassy weeds. With every g/m2 increase in weed dry weight, the fresh turmeric rhizome yield was reduced by 64.2 kg/ha. Pre-emergence atrazine/metribuzin/pendimethalin fb mulch fb hand weeding had effectively controlled weeds and increased the fresh rhizome yield by 54.1 to 54.9%, cured rhizome yield by 57.6 to 59.4% and net return by 66.4 to 68.3% being comparable to hand weeding thrice. However, hand weeding thrice was the costliest treatment. Atrazine/metribuzin/pendimethalin fb mulch fb hand weeding had lower weed persistence index and weed index and higher weed management index, agronomic management index, integrated weed management index and overall impact index than other treatments. Residues of metribuzin, atrazine, pendimethalin, oxyfluorfen and metsulfuron--methyl in soil and rhizomes of turmeric were found below detectable level. Based on overall impact index metribuzin fb mulch fb hand weeding, atrazine fb mulch fb hand weeding and pendimethalin fb mulch fb hand weeding in that order are recommended as an alternative to hand weeding thrice in turmeric.