Plant protection issues. I. A commentary on new weeds in the United States.
The following topics are discussed with reference to the control of exotic weed species recently introduced to the USA: the factors that influence the transition of an innocuous species into a problematic weed, as exemplified by Ipomoea triloba, Melaleuca quinquenervia, Urochloa panicoides and Nassella trichotoma; background and weed control information about established and novel species that may be useful for devising control strategies for the latter; and the role of plant protection agencies and other legislative bodies. It is suggested that weed management strategies should include the following: prevention (from entering foreign commerce); exclusion (detection of weed contaminants in imported products at ports of entry); detection, containment and eradication of incipient infestations; and continual control of widespread species.