The weed originates in South America but is known in New Zealand as Onehunga weed as it was first noticed in this Auckland suburb.
Onehunga weed is probably New Zealand’s most hated weed. It is the rotter that spoils otherwise fun Summer time lawn activities. The seeds lie dormant under the soil until the wet weather arrives in Autumn, causing the seeds to germinate and grow over Winter. These seeds are viable for up to 7 years! Once the plant is established it produces clusters of thorny seeds that are painfully distributed by unsuspecting bare feet.
Our spray is perfect on dry or dewy grass and we don’t mind a little bit of wind as our spray nozzles are close to the ground so there is little to no drift in a light breeze, but if it is raining or the wind is strong we will postpone spraying until the next clear day.
The weed's growth in New Zealand occurs over Winter and is prevalent from May/June so spraying any time from then is suitable and effective.
NOTE: It is preferable to spray coastal areas in June/July (ie., Mount Maunganui, Papamoa, Pukehina, etc) as these areas develop thorns quicker than inland areas. Properties up high and inland such as Pyes Pa, Whakamarama etc should be sprayed in August/September)
Fish are susceptible to poisons of any kind so we always play it safe by keeping spray at least a metre away from fish ponds (or any aquatic systems), and we will not spray at all if it is too windy.