Spray vs hand weeding
I read Meriel Watts’ article with interest in the Gulf News last week (20 November 2014) about spraying at Whakanewha. Having worked 16 years at the park I have an historic understanding of why things have been done the way they have.
I think it’s important that people understand that we have to bring many of these seriously degraded environments back from over a hundred years of neglect, as was the case at Whakanewha. It was a long abandoned farm with a few patches of old remnant forest, and most of the land was covered with regrown but seriously weed infested kanuka forest.
Waiheke (Weedheke) suffers from some of the worst weed problems in the world, second only, I’m told, to Hawaii. The early owners of holiday baches on Waiheke used quick growing ground covers and plants that survived droughts. These quickly got out of control and during the holiday garden cleanup, they were thrown into the neighbouring reserve or else ran rampant onto neighbouring sections.
I met Meriel soon after I started at Whakanewha due to her stance on the use of herbicides. The first weed control we did at the park was done entirely by hand with some courageous volunteers. It didn’t take more than a couple of days for them to realise that the scale of the task of removing the legions of weeds from Whakanewha was beyond the scope of hand removal,
Whilst I agree with Meriel that grasses can be mown to control them, you certainly won’t get rid of kikuyu and buffalo grass from the edges of wetland areas by hand removal. The careful use of herbicides was necessary to create the beautiful wetland sequences you now see on the Whakanewha foreshore. Wherever feasible or possible, weeds should be controlled manually.
Where Meriel was standing in the photo last week was an area that was thickly infested with tobacco weed and gorse when the park was bought. It wouldn’t look like that without the use of herbicides.
Much of the clearance was done by heavy mulching machinery, with follow up broadleaf spraying to preserve grass weed seedlings and manual removal. It is very difficult to appreciate just how hard the work, care and attention went into balancing the use of herbicides with the use of manual labour. And manual labour was always favoured. Those lovely native grass areas by the dotterel sculpture did not happen by magic and would be severely degraded without the control of invasive introduced grasses.
Thousands of hours of volunteer labour have been put into whakanewha over the years, hand pulling moth plant vines and seedlings and any other weed that can be removed in that way. However, there are other weeds that can’t be removed by hand with the human resources available to us in New Zealand.
Climbing asparagus is a case in point. More than a third of the entire park area was densely infested with this weed, and it has substantially disappeared because of the use of glyphosate herbicide over the years. Thousands have enjoyed the park with no ill effects as a result of this. The park actually had some very healthy beehives in an area that was sprayed with glyphosate for several years to control climbing asparagus that were unaffected. Andy Spence, Onetangi
PS: I’d be happy to go into more detail as it’s really important that we don’t get an over-reaction from an ill informed public.
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Demonstration please
Could Meriel Watts please tell us how we can remove these weeds from our parks; ginger, moth plant, smilax, climbing asparagus and honeysuckle? If you wish to demonstrate your methods, Gary Witton could find a suitable place for a trial. Judging would be on effectiveness, cost, and collateral damage.
I have some very big problems with your claims.
Firstly, you do not give any references to back up your claims – sources are needed.
Secondly, you seem to think that “organic” sprays are safer than the “chemical sprays” they replace. A very dangerous assumption. Lastly, the sprays you have recommended the Council use on road verges are desiccants, which are almost useless against perennial weeds. John Smeed, Surfdale.
Source: Waiheke Gulf News, 27 November 2014
Weed Management Advisory 