Biological control and integrated management programs have resulted in declines of M. quinquenervia in Florida. As a result of the Melaleuca Management Plan (see Integrated Management) almost 40 000 hectares or 100 000 acres of natural area have been cleared of melaleuca (Laroche 1999). Unfortunately, an almost equal expansion of melaleuca on privately held lands has occurred, resulting in no net loss of melaleuca (Laroche 1999). The greatest declines in melaleuca density have occurred in dry rather than seasonally flooded habitats.
Melaleuca is on both the United States’ Federal Noxious Weed List and the Florida Prohibited Aquatic Plant List (Class I Prohibited aquatic plant); these listings makes it illegal to possess, sell, cultivate or transport melaleuca in Florida (Buckingham 2001; Gioeli and Neal 2004).
Bio-control programs have been successful in releasing a weevil and a psyllid to feed on melaleuca populations in southern Florida (Laroche 1999). In 1997 the leaf-feeding melaleuca snout beetle (Oxyops vitiosa) was released; the melaleuca snout beetle offers partial control of melaleuca but because it must pupate in the soil it is unable thrive in inundated habitats (Centre et al 2006). The melaleuca psyllid (Boreioglycaspis melaleucae ) was released in February 2002 (Wineriter Halbert & Cuda 2008); it is a phloem-feeder (sap-feeder) which completes its entire life cycle within the plant, avoiding the limitations of soil pupation faced by the melaleuca snout beetle. B. melaluecae has established abundantly and reduces seedling recruitment and stump regrowth of melaleuca without affecting non-target species (Center et al, 2006; Center et al, 2007). As of October 2002, the melaleuca psyllid has been released in five Florida counties: Broward, Collier, Lee, Miami-Dade and Palm Beach; it will be introduced or spread naturally to all 22 central and south Florida counties where melaleuca infestations occur (Wineriter Halbert & Cuda 2008). Both O. vitiosa and B. melaleucae were successfully made available to the public by the Melaleuca Biological Control Agent Distribution Extension Program that allowed their order on-line from 2003 to 2004 (Gioeli & Neal, 2004).
The sawfly (Lophyrotoma zonalis) is a potential bio-control agent; host-range testing and quarantine studies began in Florida in early 1994 (Balciunas and Burrows 1997). Larvae of L. zonalis eat leaves and occasionally defoliate large trees in melaleuca’s native Australia; if this species is released and establishes, it has the potential to cause major stress or damage to melaleuca (Balciunas & Burrows 1997, in Buckingham 2000).
Current efforts to restore southern Florida ecosystems are threatened by the continuing range expansion of melaleuca and other weeds (Buckingham 2000). A multi-agency task force comprised of scientists and resource managers organised by the Florida Exotic Pest Plant Council (EPPC) designed the Melaleuca Management Plan for Florida (Laroche 1994) (Mazzotti et al. 1997). No other invasive exotic has such a clearly articulated management plan as M. quinquenervia (Mazzotti et al. 1997). The Melaleuca Management Plan for Florida (Laroche 1994) is a synthesis of years of research and practical experience in melaleuca biology and management. One of its main objectives is to coordinate with and support the goals of the south Florida Ecosystem Task Force. Please see the updated Melaleuca Management Plan (1999).