Common cottonwood-based agroforestry system is widely adopted in Indian Indo-Gangetic plains. The stem cuttings of common cottonwood are raised in a nursery 10 to 12 months in rows spaced 0.5mx 0.5 m, before re-planting in the field. The longer duration of 10 to 12 months and wider spacing of stem cuttings in the nursery makes the entire transplants highly vulnerable to weed competition, especially during early establishment stages. The efficacy of preemergence herbicides and plastic and straw mulches for weed management in common cottonwood nursery was investigated at two sites in years 2014 and 2015. The major weed flora in the experimental field consisted of three grass weeds (crowfootgrass, feather lovegrass, and southern crabgrass), and four broadleaf weeds (scarlet pimpernel, garden spurge, niruri, and lesser swinecress). The integrated use of pendimethalin or alachlor applied PRE with paddy straw mulch significantly reduced density and biomass of both grass and broadleaf weeds compared to herbicide or straw mulch used alone, and provided similar level of weed control to hand weeding at both locations. Spreading of plastic mulch in the whole field after punching holes for common cottonwood stem cuttings, or in row spaces recorded similar weed control to hand-weeding. The integrated use of herbicides with straw mulch, and or plastic mulch alone significantly improved plant height, stem diameter, below- and aboveground biomass of common cottonwood plants compared to unweeded check. The study concluded that integrated use of herbicides plus paddy straw mulch or plastic mulch alone could be adopted for weed management in common cottonwood nursery plantations.
Nomenclature: Alachlor; pendimethalin; crowfootgrass, Dactyloctenium aegyptium (L.) Willd.; feather lovegrass, Eragrostis tenella (L.) Beauv. ex Roemer & J.A. Schultes; garden spurge, Chamaesyce hirta (L.) Millsp.; lesser swinecress, Coronopus didymus (L.) Sm.; niruri, Phyllanthus niruri L.; scarlet pimpernel, Anagallis arvensis L.; southern crabgrass, Digitaria ciliaris (Retz.) Koel.; common cottonwood, Populus deltoides Marshall.