Effects of alternative management systems on weed populations in hazelnut ( Corylus avellana L.)

Abstract

Weed management in hazelnut is a major production challenge, with glyphosate being the main herbicide used. Field trials were conducted from 2003 to 2005 to evaluate effects of cover crops on weed populations, and assess efficacy of mechanical control methods used alone or in combination with herbicide applications. The cover crop treatments consisted of ryegrass ( Lolium multiflorum Lam.), hairy vetch ( Vicia villosa Roth.), and red clover ( Trifolium pratense L.). Mechanical control methods (rotary hoeing and cutting by sickle) were combined with glyphosate, paraquat, and a mixture of pendimethalin and fluazifob- p-butyl. When compared with the bare soil system, the cover crops reduced weed density, number of weed species that emerged, and total weed dry biomass. Residues from the cover crops suppressed Urtica urens L., Convolvulus arvensis L., Chenopodium album L., Lapsana communis L., and Poa annua L. Weed dry biomass was significantly reduced in the cover crop treatments at 20 days after desiccation. Mechanical control methods improved weed control compared with the weedy treatment, but the level of weed control was inadequate. Satisfactory weed control was achieved when mechanical control methods were combined with herbicide applications. This study shows that cover crops and mechanical weed control methods could be used to improve weed management in hazelnut orchards.