Wild Mustard (Sinapis arvensis L.) and Corn Poppy (Papaver rhoeas L.) Competition with Four Pea Varieties Cultivated Following Conventional or Organic Farming Practices Dimitrios BILALIS 1 , Anestis KARKANIS 2* , Ilias TRAVLOS 1 , Andreas ANTONIADIS 1 , Georgia NTATSI 1 , Penelope BEBELI 1 , Dimitrios SAVVAS 1 1 Department of Crop Science. Agricultural University of Athens, Greece. 2 Department of Agriculture Crop Production and Rural Environment, University of Thessaly, Greece. *)corresponding author, e-mail: anekark80@yahoo.gr BulletinUASVM Horticulture 72(2) / 2015 Print ISSN 1843-5254, Electronic ISSN 1843-5394 DOI:10.15835/buasvmcn-hort:11633 Abstract A field experiment was carried out to determine the effects of cultural system and pea varieties on weed flora, under Mediterranean conditions. The experiment was laid out in a split-plot design with four replicates having two main plots (conventional and organic farming system) and four sub-plots (pea varieties: Onward (commercial variety), Amorgos, Andros and Schinousa (local varieties). Our results indicate that the pea varieties varied in their ability to compete with weeds. The commercial variety Onward showed significantly lower competitive ability against weeds in both cultural systems. Finally, pendimethalin provided 66% and 70% control of Sinapis arvensis and Papaver rhoeas, respectively. Keywords: competition, organic, pea, varieties, weed. Introduction Field pea is an important grain legume in Europe. Weeds are a major problem in both conventional and organic pea crops. Harker et al. (2001) observed that pea yield losses due to weed competition ranged from 40 to 70%. Wild mustard (Sinapis arvensis L.) and corn poppy (Papaver rhoeas L.) are among the most important broad-leaved weeds in pea and other winter legumes. Appropriate crop and variety selection has the potential to significantly influence the weed density (Bilalis et al., 2009; Efthimiadou et al., 2009) in both organic and conventional cultural systems. Aims The aim of this study was to determine the effects of four pea varieties on wild mustard and corn poppy density in conventional or organic farming systems. Materials and methods A field experiment was carried out in central Greece (Aliartos, 95 km northwest of Athens) in 2014-15. The pea crop was sown on 20 November 2014. The experiment was laid out in a split-plot design with four replicates having two main plots (conventional and organic farming system) and four sub-plots (pea varieties: Onward (commercial variety), Amorgos, Andros and Schinousa (local varieties). The sub-plot size was 10.5 m 2 . On conventional plots, the herbicide pendimethalin (Stomp Aqua 455 CS; BASF, Athens, Greece) was applied pre-emergence at a rate of 1137.5 g a.i./ ha -1 . Moreover, 570 kg ha -1 of fertilizer (11-15- 15, N:P 2 O 5 :K 2 O) and 7.6 ton ha -1 of sheep manure brought to you by CORE View metadata, citation and similar papers at core.ac.uk