excessive dune disturbance. Gallant
TM (Gallant-NF
TM , Gallant-Ultra
TM
), a selective (grass-specific), systemic herbicide has been used by the Department of
Conservation since the mid 1980s. Gallant can be sprayed on pı ¯ngao (or ‘‘pı ¯kao’’
in southern New Zealand), a sedge, at usual concentrations and application rates,
without stress or necrosis. Spinifex sericeus, a grass, does not grow in southern
New Zealand. However, Gallant cannot be used in the presence of native grasses,
including the native sand tussock, Poa billardierei. Gallant has two disadvantages.
It is relatively expensive at around NZ$ 180/liter (in 2010). Second, the effects
when used on marram grass are relatively slow to appear—in southern New
Zealand (47° S Lat.) 12 months should be left between application and assessment.
That is, the effectiveness of a marram eradication operation cannot be assessed
until the following growth season. Complete necrosis of above-ground biomass is
usually observed within 6 months of herbicide application, but regrowth can be
anticipated in early spring. Other ‘‘knockdown’’ herbicides have been trialed, but
they have been found to be less effective and more expensive over time. Gallant
remains the best option.
Prior to the formation of the Department of Conservation in 1987, the New
Zealand Forest Service targeted the northwest beaches of Stewart Island, which
then contained small infestations of marram, of the order of 10
1 –10
2 m
2 . These
populations had developed from rhizome that may have originated on the west
coast of Stewart Island, Southland or South Westland. Knapsacks were used to
apply Gallant from time to time, depending on other priorities, the availability of
transport, and the weather. The beaches of northwest Stewart Island are accessed
by boat or small aircraft that are capable of landing at low tide. These operations
were of the utmost importance, since they prevented the establishment of large
infestations at a time when there was no policy or funding for the systematic
control of marram grass on Stewart Island.
The Department of Conservation commenced aerial (helicopter) operations in
Doughboy Bay in February 1999. By this time marram had produced a dense cover
over the northern and southern barriers and was rapidly invading the central dunes.
The area of dense marram, associated with the four foredune ridges described
above, an area of approximately 7 ha, was sprayed with the herbicide Gallant
NF
TM using a Robinson-22 helicopter in February (mid-summer) 1999. Helicopters have since been used to spray large areas of marram grass, particularly marram
growing in the foredune environment, primarily using Jet-Ranger aircraft
(Fig. 5.12). The 1999 helicopter operations on the southern barrier at Doughboy
Bay were repeated in 2000 and 2001. The initial results were spectacular—complete necrosis of leaf material was observed 4 months after the first helicopter
operation. However, numerous shoots had established from surviving rhizome by
late spring. The helicopter was used to spray this regrowth in February 2000.
Further regrowth was sprayed during the summer of 2000/2001 using a 500 liter
pump unit mounted on an ARGO amphibious vehicle (Fig. 5.13). Subsequent
regrowth, primarily from in situ seeds, has been sprayed using the ARGO or with
knapsacks, or hand-pulled during systematic search and destroy operations in the
5 Restoration of Foredunes and Transgressive Dunefields
81
TM (Gallant-NF
TM , Gallant-Ultra
TM
), a selective (grass-specific), systemic herbicide has been used by the Department of
Conservation since the mid 1980s. Gallant can be sprayed on pı ¯ngao (or ‘‘pı ¯kao’’
in southern New Zealand), a sedge, at usual concentrations and application rates,
without stress or necrosis. Spinifex sericeus, a grass, does not grow in southern
New Zealand. However, Gallant cannot be used in the presence of native grasses,
including the native sand tussock, Poa billardierei. Gallant has two disadvantages.
It is relatively expensive at around NZ$ 180/liter (in 2010). Second, the effects
when used on marram grass are relatively slow to appear—in southern New
Zealand (47° S Lat.) 12 months should be left between application and assessment.
That is, the effectiveness of a marram eradication operation cannot be assessed
until the following growth season. Complete necrosis of above-ground biomass is
usually observed within 6 months of herbicide application, but regrowth can be
anticipated in early spring. Other ‘‘knockdown’’ herbicides have been trialed, but
they have been found to be less effective and more expensive over time. Gallant
remains the best option.
Prior to the formation of the Department of Conservation in 1987, the New
Zealand Forest Service targeted the northwest beaches of Stewart Island, which
then contained small infestations of marram, of the order of 10
1 –10
2 m
2 . These
populations had developed from rhizome that may have originated on the west
coast of Stewart Island, Southland or South Westland. Knapsacks were used to
apply Gallant from time to time, depending on other priorities, the availability of
transport, and the weather. The beaches of northwest Stewart Island are accessed
by boat or small aircraft that are capable of landing at low tide. These operations
were of the utmost importance, since they prevented the establishment of large
infestations at a time when there was no policy or funding for the systematic
control of marram grass on Stewart Island.
The Department of Conservation commenced aerial (helicopter) operations in
Doughboy Bay in February 1999. By this time marram had produced a dense cover
over the northern and southern barriers and was rapidly invading the central dunes.
The area of dense marram, associated with the four foredune ridges described
above, an area of approximately 7 ha, was sprayed with the herbicide Gallant
NF
TM using a Robinson-22 helicopter in February (mid-summer) 1999. Helicopters have since been used to spray large areas of marram grass, particularly marram
growing in the foredune environment, primarily using Jet-Ranger aircraft
(Fig. 5.12). The 1999 helicopter operations on the southern barrier at Doughboy
Bay were repeated in 2000 and 2001. The initial results were spectacular—complete necrosis of leaf material was observed 4 months after the first helicopter
operation. However, numerous shoots had established from surviving rhizome by
late spring. The helicopter was used to spray this regrowth in February 2000.
Further regrowth was sprayed during the summer of 2000/2001 using a 500 liter
pump unit mounted on an ARGO amphibious vehicle (Fig. 5.13). Subsequent
regrowth, primarily from in situ seeds, has been sprayed using the ARGO or with
knapsacks, or hand-pulled during systematic search and destroy operations in the
5 Restoration of Foredunes and Transgressive Dunefields
81