Preventing invasive and alien weeds in fields is usually easier
and less costly than controlling them after severe infestation, as it is
difficult to control weeds once they are established. Some weedpreventive
measures include the use of clean crop seeds, the use
of clean agricultural implements, and managing weeds on bunds or
levees and roads, etc. A study in Montana State University showed
that a vehicle driven through a Centaurea biebersteinii DC. infestation
picked up about 2000 seeds of C. biebersteinii, of which 90%
dropped within 10 miles (Sheley et al., 2002). The study also suggested
that minimizing disturbance of soil by vehicles, machinery,
wildlife, and livestock is central to preventing noxious weed
establishment.