Weed composition and diversity of three organic farms in Hungary.
A study was carried out on the weed composition of three different organic farms in Hungary between 2012 and 2013. The aim was to explore the dominance of weed species (based on % cover) in the fields. Weeds were assessed in 1 m2 sample quadrates randomly placed within the fields. The cover of weeds species was directly recorded by visual estimation twice in each year. The highest weed cover was found in Jászdózsa in the summer of 2012. Most of the dominant weeds, such as Setaria viridis (4.09%), Ambrosia artemisiifolia (3.20%) and Fallopia convolvulus (2.30%), were present. Some interesting and uncommon species were also found e.g. Symphytum officinale, Chorispora tenella, and Potentilla supina. In the second year the most dominant weed was the Phacelia tanacetifolia that was the previous crop in fields of Kishantos farm. The cover of monocotyledons decreased between 2012 and 2013, in the spring and the summer survey, too. Ambrosia artemisiifolia was the dominant weed in all examined areas. The relative dominance of each species changed between years, but the number of new species was very low. We found some interesting and uncommon species in these areas especially in Jászdózsa, but generally speaking, the weed flora of the investigated areas was similar.