Management Requirements: Hedychium coronarium should be controlled at Kamakou, especially in drainages because of a threat to rare mesic shrubland flora in these sites.
Kamakou staff has effectively controlled some Hedychium coronarium populations by a combination of manual and mechanical means. These labor-intensive methods are effective on invasive ginger species in Hawaii. Often considerable follow-up is needed because of the difficulty of locating and removing all rhizome fragments, which are capable of resprouting.
A mechanical method that has been effective on kahili ginger and would probably work on white ginger is repreated mowings. The shoots are cut off with a weed eater. Resprouting shoots are cut when they reach 12 inches. Ninety percent control is achieved with kahili ginger in approximately one year, although complete control may require several years (Markowitz pers. comm.).
Escort, at a concentration of 4.5 g/l of water, without a surfactant, is highly effective on kahili ginger (Hedychium gardnerianum) (Cuddihy pers. comm.(b)). This was also relatively effective on an unreplicated trial on white ginger at Hawaii Volcanoes.
Tomich (pers. comm.) found that undiluted Roundup was effective on white ginger when applied to the above ground roots emerging from the rhizomes, after the shoots were removed. However, local State Department of Agriculture officials should be consulted before using this method, which may be interpreted as a foliar application rather than a cut-surface application.
Management Programs: Hedychium coronarium has been controlled at Kalopa State Park (Tomich pers. comm.). Kamakou has successfully controlled some white ginger colonies.
Management Research Programs: Arakaki is studying the effectiveness of Escort in Hedychium coronarium control at Kamakou Preserve (Misaki pers. comm.)
Management Research Needs: Identification of an effective non-mobile herbicide would be useful in control of Hedychium coronarium at Kamakou. Detailed studies of life-history and ecology, useful for state-wide control of widespread species such as clidemia (Clidemia hirta) are not needed for a localized threat such as white ginger.