Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Weed populations in olive groves under non-tillage and conditions of rapid degradation of simazine.

Abstract

In 49 olive groves surveyed in southern Spain under non-tillage and treated in the autumn with simazine, a total of 315 weed species was identified. However, only eight annual species reached a moderate mean infestation of infested fields. In each field the number of observed species ranged from 4 to 78. The most important annual species that survived simazine treatment were Lolium rigidum, Galium tricornutum and Sherardia arvensis and, locally in a few fields, others such as Amaranthus spp., Conyza spp., Pulicaria paludosa, Sinapis alba, Torilis arvensis and Rumex bucephalophorus. Sedum album, R. bucephalophorus, P. paludosa, Briza maxima and Hypericum perforatum were mainly found in slope soils with high altitude and low carbon content. Cyperus rotundus, Conyza bonariensis, Amaranthus blitoides, Galium spurium and Diplotaxis virgata were found at high densities in irrigated fields. Simazine residues recorded 6 months after herbicide application were very low, amounting on average to levels less than 3% of the applied rate. In soil treated with simazine for 7 years, simazine degradation was much faster than in previously untreated soil, particularly at temperatures of 15-25°C.