Weed seed spread and its prevention: The role of roadside wash down

Abstract Vehicles are one of the major vectors of long-distance weed seed spread. Viable seed removed from vehicles at roadside wash down facilities was studied at five locations in central Queensland, Australia over a 3-year period. Seed from 145 plant species, belonging to 34 different families, were identified in the sludge samples obtained from the wet particulate matter collection pit of the wash down facilities. Most of the species were annual forbs (50%) with small or very small seed size ( ca. 68,000. Thus, a typical wash down facility was removing up to ca. 335,000 viable seed from vehicles per week, of which ca . 6700 were parthenium weed seed. Furthermore, 61% of these seed ( ca. 200,000) were from introduced species, and about half of these (35% of total) were from species considered to be weeds. Therefore, the roadside wash down facilities found throughout Queensland can remove a substantial amount of viable weed seed from vehicles, including the invasive parthenium weed, and the use of such facilities should be strongly encouraged.