Emergence of L. rigidum with cover crops – contribution for IWM

Abstract: Lolium rigidum Gaudin (annual ryegrass) is a major weed of olive groves in mediterranean countries but also commonly occurs as a weed of cereal crops. Its seeds have little dormancy and short-term viability. Knowledge of the germination and emergence patterns of this species can play a major role in reducing soil seed bank. This study presents the results of a common experiment of emergence of several L. rigidum populations from the point of view of weed management. 200 seeds/m2 of each L. rigidum population were seeded in 0.5 × 0.5 m plots in October 2020 with four repetitions. Periodic weed sampling was carried out from November until April. In three sites, from Spain (Andalucia and Navarra) and Portugal (Ribatejo) the emergence of a common population was followed either alone or with two cover crops, Hordeum vulgare (300 seeds/m2) and Sinapis alba (160 seeds/m2). The emergence of L. rigidum was similar among the three regions but the effect of cover cropping was different among regions. Integrating a number of practices directed to various stages of the lifecycle is key to dealing with weeds such as L. rigidum. Cover cropping could be a cultural tool for Integrated Weed Management of L. rigidum particularly in olive groves with herbicide-resistant populations.