Weed control strategies and yield response in a pepper crop (Capsicum annuum L.) mulched with hairy vetch (Vicia villosa Roth.) and oat (Avena sativa L.) residues Enio Campiglia * , Emanuele Radicetti, Robeto Mancinelli Dipartimento di Scienze e Tecnologie per l’Agricoltura, le Foreste, la Natura e l’Energia, Università della Tuscia, via S. Camillo de Lellis, 01100 Viterbo, Italy article info Article history: Received 11 July 2011 Received in revised form 22 September 2011 Accepted 23 September 2011 Keywords: Integrated weed management Conservation tillage Weed diversity Cover crops Mediterranean environment Low-input agriculture Organic agriculture Glyphosate abstract Organic mulches could be a part of a wide strategy of integrated weed management in vegetable production systems. A 2-year field experiment was carried out in Central Italy with the aim of assessing the effect of grass and legume mulches, coming from winter cover crops, combined with herbicide or mechanical hoeing on weed control, on weed community (density and aboveground biomass of each species), and yield of a pepper crop. Hairy vetch (Vicia villosa Roth), oat (Avena sativa L.) and their mixture were sown in early autumn and suppressed in May. The cover crop aboveground biomass was cut and arranged in strips which were used as beds for pepper seedlings transplanted in paired rows. A conventional treatment kept bare during the cover crop growing season with two different levels of nitrogen fertilizer on pepper (0e100 kg ha 1 of N) was also included. Three weed control treatments were applied between the paired pepper rows 30 days after transplanting: a weed free treatment, glyphosate or mechanical hoeing. Dry matter production at cover crop suppression ranged from 5.3 t ha 1 in oat to 7.1 tha 1 in hairy vetch/oat mixture and the N accumulation ranged from 56 kg ha 1 in oat to 179 kg ha 1 in hairy vetch. Within the pepper paired rows, mulch treatments reduced weed density and biomass throughout the pepper cropping season. At harvest, weed density and aboveground biomass within the pepper paired rows ranged from 1.7 to 4.6 plants m 2 and 28 and 133 g m 2 of DM, respectively. Oat mulch had the highest weed suppression ability and the lowest species richness, Shannon’s index and Shannon evenness. Between the pepper paired rows the mulch treatments had the highest species richness and the most diverse weed community in chemical compared to mechanical weed control. The densities of Portulaca oleracea L. and Polygonum aviculare L. were the highest under chemical and mechanical control, respectively. The weeds did not hinder pepper production in hairy vetch and hairy vetch/oat mixture where the yield was similar to that obtained in a conventional weed- free system fertilized with 100 kg ha 1 of N. Therefore the use of hairy vetch mulches in combination with reduced mechanical or chemical weed control could be a feasible strategy in order to control weeds and to produce high yields in a pepper crop. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction Pepper (Capsicum annum L.) is an important vegetable crop world-wide in terms of both commercial value and the role it plays in the rural economy (Gonzalez-Diaz et al., 2009). In Italy pepper is cultivated over 10,000 ha per year with an average yield production of 25 t ha 1 of fresh fruits (ISTAT, 2006). In Central Italy, the current open field pepper production, which is the most widespread compared to greenhouse production, requires a highly intensive management and the use of several applications of pesticides especially for weed control. In fact this vegetable crop competes poorly with the weeds particularly at the early growth stages (Adigun et al., 1991). Immediately after transplanting the pepper seedlings grow slowly and therefore are weak competitors for limiting resources against the weeds (Isik et al., 2009). Further- more, the abundant irrigation after crop transplanting stimulates a rapid weed growth, resulting in yield losses at harvest up to 97% (Amador-Ramirez, 2002). For these reasons weed control is recognized as the foremost production-related problem in both conventional and organic pepper crops (Amador-Ramirez et al. 2007; Isik et al., 2009). In conventional cropping systems, herbi- cides have gradually replaced tillage for controlling undesirable vegetation (Sprague, 1986), in spite of issues related to the envi- ronment (Hallberg, 1989). In organic cropping systems, where herbicides are not allowed, the reliance on mechanical cultivation is not always desirable, due to possible damage of soil structure, an * Corresponding author. Tel.: þ39 761 357538; fax: þ39 761 357558. E-mail address: campigli@unitus.it (E. Campiglia). Contents lists available at SciVerse ScienceDirect Crop Protection journal homepage: www.elsevier.com/locate/cropro 0261-2194/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.cropro.2011.09.016 Crop Protection 33 (2012) 65e73