Alligator Weed at Domain gate, 30 October 2011

Auckland Council has been treating Alligator Weed in the Marawhara, Wekatahi, and Lily Pond over the winter. Now this awful weed has turned up in the Domain. When I reported it in the swale by the Domain entrance, it looked as if it was confined to that area. But Biosecurity report that it was right through the turf on the field and grassy areas by the Lagoon edge, something that has not been encountered elsewhere as it is an aquatic weed.

The area concerned is an saltmarsh/wetland that has been gradually in-filled over 50 or so years. Old photos show water and salt tolerant plants growing in this area, and when the Piha Stream floods and the sea is high, the ground gets distinctly boggy. Clearly conditions that suited Alligator Weed.

Same area, 11 November 2011, after spraying

Alligator Weed can be identified by its bright green leaves, reddish stems and white ball-shapped flowers. It is very difficult to get rid of and it is recommended that it is a job for the experts. Hand-removal at the Marawhara had a temporary effect in the past, but chemicals are needed to deal with it.

The message from Western Local and Sports Parks says:

Alligator weed has been identified in Piha Domain. Local and Sports Parks West are working with Biosecurity to eradicate alligator weed from Piha Domain as well as the stream and lagoon edge. 

Parks will be undertaking a trial within Piha Domain to determine the most effective control.  Three products will be tested, all sprays are approved for use currently and existing spray maintenance signage will be used.  

Once the most effective spray has been identified, spraying will be undertaken within the affected area.  The initial spray will be undertaken the week of 19 December 2011 at 7am.  Spraying of this area would be completed by 9am before peak visitor times.  Appropriate signage will be used.  There will be no issue with the public using this area after spraying is completed.  

The weed will be monitored on a fortnightly basis after the initial spraying.  Additional spraying may be required in February with all work concluding prior to the planned field upgrade works in March/April 2012. 

If you have any questions about this work please contact Annette Richards at Annette.richards@aucklandcouncil.govt.nz or phone 301 0101 extension (42)8375.

Alligator weed, Marawhara Stream, March 2011