Impact of Cereal Rye Seeding Rate and Planting Method on Weed Control in Cotton

Costs related to herbicide use have increased greatly due to evolution and proliferation of glyphosate-resistant Palmer amaranth (Amaranthus palmeri S.). The use of cover crops in conservation tillage offers advantages such as weed suppression through physical and allelopathic effects. A field study was initiated in fall 2013 and 2014 in Fayetteville, AR to determine the impact of cereal rye (Secale cereal L.) seeding rate and planting method on weed control and cotton (Gossypium hirsutum L.) yield. Cereal rye seeding rates were 56, 112, and 168 kg ha-1 in absence or presence of a herbicide program. Planting methods consisted of drilled and broadcast. No differences were observed between planting methods in any parameter evaluated. In both years, cereal rye biomass production increased as seeding rate increased. When herbicides were not applied, cereal rye at 56 kg ha-1 provided the least weed control. Cereal rye at 112 and 168 kg ha-1 provided comparable levels of Palmer amaranth control. At 8 wk after cotton planting, all plots treated with a commonly used herbicide program had 99% or greater grass control, regardless of the seeding rate. Yields from plots with a standard herbicide program were greater than from plots without herbicide. Yield improvement was observed due to use of cereal cover crop compared to no cover crop in 2014, whereas no differences were observed in 2015.