Stands of gorse colonizes large mid
to upper elevation tracts, shown here on the island of Hawai‘i. During
flowering season (right) its appearance is striking.Gorse is a sharp-spined leguminous shrub that has become a serious weed problem in several countries where it has been introduced for cultivation as "living fences" around sheep and cattle pastures. It has become widely established in open grass- and shrubland in Hawai‘i. It is especially well-established on the islands of Hawai‘i and Maui.
Stands of gorse colonizes large mid
to upper elevation tracts, shown here on the island of Hawai‘i. During
flowering season (right) its appearance is striking.
Unlike many of the forest weed problems in Hawai‘i, interest in controlling gorse is shared by several countries. Knowledge of bioncontrol approaches is therefore available to be shared on a wider basis than is often the case in which a given alien species is a weed problem in only one region, such as Hawai‘i. For this reason, several arthropod biocontrol agents are known, including insects that attack different parts of the plant, and a web-forming mite already released in the field in New Zealand, are available for testing in Hawai‘i.
In addition to the arthropods, the uredinial state of a rust fungus (Uredo sp.) from Great Britian, the putative native habitats of gorse, has been imported into quarantine in Hawai‘i, where it was tested for host-specificity by Hawai‘i Department of Agriculture plant pathologists. Although host testing has shown the rust to be specific for gorse, the identity of the fungus is in question. Telia, upon which the taxonomy of rust fungi typically is based, have not been observed during the current study. Because of this difficulty, plans to release the fungus into the field have been suspended until the ambiguity can be resolved.
The rust fungus (Uredo sp.)
on gorse has been shown to be virulent and host-specific, but the lack of a telial state
causes its identity to be uncertain.