FLORA AND WEED MANAGEMENT IN CITRUS ORCHARDS.

Flora surveys were carried out in 50 lemon orchards from Mafra, in the Oeste region of Portugal, during spring-summer and autumn-winter of 2002. A total of 62 species with relative frequency higher than 15% were identified, 44 in autumn-winter and 42 in spring-summer. The most representative families were Asteraceae, Poaceae and Fabaceae, in autumn-winter, and Asteraceae, Poaceae, Polygonaceae and Chenopodiaceae, in spring-summer. The results of a study conducted in lemon orchards from the Oeste region and a sweet orange orchard from Algarve, comparing the influence of three ground cover systems in the flora dynamics, including resident vegetation, sowing of selected plant species and herbicide application, are presented and discussed.