The Happy Florist

Preventative measures

A Risk Assessment of Acacia mearnsii for Hawai’i and other Pacific islands was prepared by Dr. Curtis Daehler (UH Botany) with funding from the Kaulunani Urban Forestry Program and US Forest Service. The alien plant screening system is derived from Pheloung et al. (1999) with minor modifications for use in Pacific islands (Daehler et al. 2004). The result is a score of 15 and a recommendation of: “Likely to cause significant ecological or economic harm in Hawai’i and on other Pacific Islands as determined by a high WRA score, which is based on published sources describing species biology and behavior in Hawai’i and/or other parts of the world.”

Chemical

Saplings sensitive to foliar applications of triclopyr. Dicamba, glyphosate and picloram applied cut-surface effective, triclopyr probably effective, although applications to drilled holes in larger trees probably necessary. Cut-surface (notching) applications of picloram provided complete control, glyphosate and dicamba caused 80% control, and 2,4-D was inadequate at Kala’e, Molokai. Alton Arakaki (Univ. Hawai’i) and Ed Misaki of The Nature Conservancy (TNC) confirmed the efficacy of picloram but got much better results with glyphosate and dicamba, each resulting in over 90% control at Kamakou Preserve. Basal bark and stump bark treatments with 2,4-D or triclopyr effective. Pat Bily (TNC) reported that basal bark applications with triclopyr ester at 20% in oil was effective, as was cut stump application of triclopyr amine at 50% in water. Hawaiʻi Volcanoes National Park (HAVO) staff got good control with triclopyramine at 10% in water applied to cut stumps (Chris Zimmer, HAVO). Anecdotes indicate that wattle is sensitive to basal bark treatment with diesel alone and to girdling.

Biological

The use of Cecidomyiidae gall midges to inhibit reproduction of Acacia species is being researched for use in South Africa. A Dasineura sp. has been identified as a promising control agent as it prevents fruit formation (and thus reproduction) without affecting vegetative growth (which may be a concern for industries or commerce that rely on the species). Dasineura is also known to have a narrow host range. Melanterius maculatus, a seed-eating weevil (native to Australia), was introduced into South Africa in 1993 and caused reductions in A. mearnsii seed numbers in some areas. Larvae feed on developing seeds inside the pods and adults feed on the green pods and pinnules. In South Africa a local stump-colonising fungus has been isolated and added to cut trees to prevent regrowth. Finally, a wasp (Bruchophagus acaciae) has been described that attacks the seeds of some Acacia species but not those of A. mearnsii (Adair et al., 2000; Adair, 2002; ARC-PPR, 2003; Hill, Gordon and Neser, 1999).

Integrated management

The Working for Water programme implemented by the South African government is a collaborative program that aims to ameliorate the problems caused by Acacia species and other invasive plants. The program consists of more than 300 sub-projects in all nine provinces in the country and consists of the clearing of weeds from water courses (by mechanical and chemical methods). Between 1995 and 2000 over $100 million of poverty-relief funds on the program which was labor intensive and provided job opportunities for local communities. After seven years of implementation of the project it became clear that rehabilitation of sites (following the removal of alien plant species) would sometimes be needed in order to prevent or reduce the soil erosion stimulated by the clearing of plants (Van Wilgen et al., 2002, Milton, Dean and Richardson, 2003).

Source: http://en.wikipedia.org/wiki/Acacia_mearnsii

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This entry was posted on Tuesday, June 15th, 2010 at 6:25 pm and is filed under Flowers. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.