Distribution of Invasive Weed Ambrosia artemisiifolia L. in Croatia

Ambrosia artemisiifolia L., is an invasive alien plant in Europe that has been the subject of research of many scientifi c disciplines, particularly in last twenty years. In addition to being known as a noxious weed, it came into the public interest as a source of very strong allergenic pollen that causes allergic responses in 10% of the Croatian population, a fi gure similar to that of other European countries. Th e genus Ambrosia consists of about 40 species but in Europe just fi ve of them are present. Th e most widespread is Ambrosia artemisiifolia L. It is present normally in row crops, particularly in sunfl ower (Helianthus annuus L.) fi elds. Furthermore, its presence is noticed along communication lines, in urban, industrial and building areas, and other non-agricultural areas. Distribution monitoring of Ambrosia artemisiifolia L. was conducted during three years, from 2004 to 2006, by recording its presence or absence in settlements of districts in the 21 counties of Croatia. Inland parts of Croatia are highly infested with Ambrosia artemisiifolia L. while in the coastal area it is mainly concentrated on bands along communication lines. In this area we observed individual (solitary) plants. Systematic and well organized monitoring of the Ambrosia artemisiifolia L. spread and distribution in the coastal parts of Croatia would reduce its progression to the more southern parts and the Croatian islands.