New infestations of alligator weed have been found in Morrinsville, on a farm near Matamata and on a farm near Whangamarino.
Environment Waikato biosecurity officer Wendy Mead is urging the public to be on the lookout for this invasive pest.
“This is the Waikato region’s worst weed,” Ms Mead said.
“In the past 12 months there has been a significant increase in its spread and landowners, particularly farmers, should be aware of the threat it poses to farm productivity.”
Alligator weed is an extremely invasive weed with vigorous growth, enabling it to out-compete pastures and crops. It is also toxic to livestock. It grows very easily, even from the smallest fragments, and can be spread by cultivation and soil movement.
There have been two cases of alligator weed growing amongst maize crops in the Waikato region, and farmers need to be aware it can spread via harvesting and contracting equipment.
“Nearly all infestations of alligator weed in the Waikato are believed to have occurred due to movement of contaminated soil or contracting equipment,” Ms Mead said.
Unwanted weeds can spread when farmers purchase crops like maize for feed supplements, and can be ‘imported’ via diggers, harvesters and similar equipment.
“It is important that landowners enforce their own ’border control’ requirements by insisting machinery is decontaminated of weed material and seed heads before it enters their property,” Ms Mead said.
“It is obvious that in most cases weed dispersal is aided by machinery.”
Alligator weed grows in water, posing a serious threat to the region’s rivers, lakes, streams and wetlands, and it can take over lawns and gardens in urban areas.
“In Hamilton city the spread of alligator weed is closely associated with subdivision development activities such as soil movement and contaminated equipment,” Ms Mead said.
Environment Waikato is responsible for the control of alligator weed. The plant is categorised as a direct control pest plant in the Regional Pest Management Strategy and the council takes responsibility for spraying to eradicate it. The budget for its control has expanded dramatically over the past five years as a result of the proliferation of sites where it has been discovered.
The plant has bright green, waxy leaves, arranged in opposite pairs along the stem, and it can be recognised at this time of the year by its small white, clover-like flowers.
If you think you have seen alligator weed please call Wendy Mead at Environment Waikato on 0800 800 401, or phone your local plant pest contractor on 0800 BIOSEC (0800 246732).