Submitted to: Integrated Pest Management Symposium Workshop Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: July 13, 2007
Publication Date: July 28, 2007
Citation: Rayamajhi, M.B., Pratt, P.D., Center, T.D., Laroche, F. 2007. Integrated management of the invasive tree Melaleuca quinquenervia in southern Florida: Special emphasis on the natural enemy impact . Integrated Pest Management Symposium Workshop Proceedings. Interpretive Summary: Melaleuca trees have invaded and replaced native vegetation in various landscapes of southern Florida. Therefore, control measures such as mechanical, chemical, cultural, and biological have been developed and used to manage further spread of this tree species. Mechanical and chemical methods are being used to kill larger trees while cultural and biological control measures are being used to reduce seedling recruitment. Natural enemies that feed only on melaleuca (weevils and psyllids) have been introduced from Australia. During the last 8-years, these and other adventive organisms (a scale insect and a rust fungus) have affected tree health, cut down seed quality and quantity, and reduced further spread. Overall integration of the above mentioned control methods have reduced melaleuca populations and their densities in southern Florida. Reduced melaleuca densities have created spaces where many native plants have now begun to establish. As a result, melaleuca monocultures in many parts of south Florida are being converted into community of mixed vegetation.
Technical Abstract: The Australian tree Melaleuca quinquenervia (melaleuca) has rapidly invaded the south Florida landscapes at the expense of native plant communities. Hence, an integrated melaleuca management program involving mechanical, chemical, cultural, and biological control methods was developed and is being used by various agencies. Mechanical and chemical methods have been used in eliminating larger trees while cultural and biological control measures reduce seedling recruitment. Natural enemies involved in this program are introduced specialized insects from Australia as well as an adventive pathogen and a scale insect. Their impact on melaleuca populations has been monitored since 1997. The insect-fungus interactions caused chronic defoliation and dieback resulting in additive impacts that inhibited melaleuca stump-regrowth, reduced tree densities, and diminished basal area production due to accelerated tree-mortality. Further spread of melaleuca has ceased as natural enemies killed a large proportion of melaleuca trees and reduced the reproductive potential of surviving trees. By 2005, canopies had opened allowing native species from surrounding areas to colonize the stands. As a consequence, plant species richness and diversity indices were higher compared to 1996 when melaleuca stands consisted of dense monocultures. Integration of these mechanical, chemical, cultural, and biological control methods have been successful in containing melaleuca populations in many parts of southern Florida.