Chilean Needle Grass the ultimate weed
Chilean Needle Grass is a very invasive tussock grass that is very difficult to control. It infests parts of Hawkes Bay and extensive areas of Marlborough. Seeds will puncture sheep pelts rendering them worthless, and cause abscesses in carcasses. It is virtually impossible to eradicate in heavily infested areas because of its capacity to produce several types of seeds that last for at least a decade. In short, its a prick of a weed.
Sprays are of limited value, although there is a new one being tried in Australia. Containment in infested areas and eradication in fringe areas are District Council policies in Marlborough. Thorough cleaning of machinery that has been working in infested areas is essential.
Ben Minehan, Biosecurity Officer (Team Leader) with Marlborough District Council, describes Chilean Needle Grass (Nasella neesiana, formerly Stipa neesiana) as the ultimate weed. It has aerial seeds on top that cause problems with stock, he says, and it also has seeds inside the stems and in the bulb (cleistogenes). The cleistogenes are viable even before the flowering head comes out, so that even when sprayed with glyphosate and the plant appears to die it can grow again the next season or two seasons later from the cleistogenes. That's why we are really not getting on top of it. It is the biggest weed issue in this area because of its nature, and the hardest weed that we deal with.
Key features:
An erect perennial grass that grows up to 1m high if not grazed
Produces sharp-tipped seeds which can bore into eyes and pelts of sheep, renders pelts valueless and can cause abscesses in carcasses
Smothers preferred pasture species
Difficult to identify when growing in pasture and so is often not recognised until dense patch has formed, which has already produced large amounts of aerial seed
Is easily spread through stock, hay, water, vehicle or soil movements but not by wind
First discovered in NZ in 1930s, but only two extensive populations in country Marlborough and Hawkes Bay. It was first seen in the Blind River area of Marlborough
In Marlborough about 5000ha is affected and new infestations are being found each season. Some properties are 90% covered with CNG
Land use changes, soil movements on heavy machinery, and livestock movements out of the district make containment very difficult
Stock will eat it but prefer other species and so it gets away and forms aerial seeds.
Control:
Small patches can be grubbed and bagged and plants destroyed. That is reasonably successful but there is such a huge seed bank new plants keep coming up.
Large areas in pasture need to be cultivated and cropped about every three years
Spraying with glyphosate plus Crovar makes the soil barren for about 4 years and so is not suitable for large areas
A new chemical, sodium tetrafluoropropanate (generally referred to as fluoropropanate), is being used with some success in Australia, and Ben Minehan would like to see it introduced here.
Measures to avoid spread via hay, stock, water, vehicle, machinery and soil movements.
Council policy
In core areas, plants within 10m of the property boundary must be destroyed before they produce seed. Other plants should be subject to a control programme.
In fringe areas all plants must be destroyed before they produce seed.
Says Ben Minehan: There has been a huge amount of money spent on the problem over the years, and we are struggling to contain it. It is very easily spread through earth moving machinery travelling between properties and so on, and operators wash all machinery down before they leave a farm in an infested area.
People don't appreciate the long-term implications once it gets onto a property Chilean needle grass is very difficult to control but a little bit of thought and good hygiene between properties is going to avoid huge problems in the future.
Sprays are of limited value, although there is a new one being tried in Australia. Containment in infested areas and eradication in fringe areas are District Council policies in Marlborough. Thorough cleaning of machinery that has been working in infested areas is essential.
Ben Minehan, Biosecurity Officer (Team Leader) with Marlborough District Council, describes Chilean Needle Grass (Nasella neesiana, formerly Stipa neesiana) as the ultimate weed. It has aerial seeds on top that cause problems with stock, he says, and it also has seeds inside the stems and in the bulb (cleistogenes). The cleistogenes are viable even before the flowering head comes out, so that even when sprayed with glyphosate and the plant appears to die it can grow again the next season or two seasons later from the cleistogenes. That's why we are really not getting on top of it. It is the biggest weed issue in this area because of its nature, and the hardest weed that we deal with.
Key features:
An erect perennial grass that grows up to 1m high if not grazed
Produces sharp-tipped seeds which can bore into eyes and pelts of sheep, renders pelts valueless and can cause abscesses in carcasses
Smothers preferred pasture species
Difficult to identify when growing in pasture and so is often not recognised until dense patch has formed, which has already produced large amounts of aerial seed
Is easily spread through stock, hay, water, vehicle or soil movements but not by wind
First discovered in NZ in 1930s, but only two extensive populations in country Marlborough and Hawkes Bay. It was first seen in the Blind River area of Marlborough
In Marlborough about 5000ha is affected and new infestations are being found each season. Some properties are 90% covered with CNG
Land use changes, soil movements on heavy machinery, and livestock movements out of the district make containment very difficult
Stock will eat it but prefer other species and so it gets away and forms aerial seeds.
Control:
Small patches can be grubbed and bagged and plants destroyed. That is reasonably successful but there is such a huge seed bank new plants keep coming up.
Large areas in pasture need to be cultivated and cropped about every three years
Spraying with glyphosate plus Crovar makes the soil barren for about 4 years and so is not suitable for large areas
A new chemical, sodium tetrafluoropropanate (generally referred to as fluoropropanate), is being used with some success in Australia, and Ben Minehan would like to see it introduced here.
Measures to avoid spread via hay, stock, water, vehicle, machinery and soil movements.
Council policy
In core areas, plants within 10m of the property boundary must be destroyed before they produce seed. Other plants should be subject to a control programme.
In fringe areas all plants must be destroyed before they produce seed.
Says Ben Minehan: There has been a huge amount of money spent on the problem over the years, and we are struggling to contain it. It is very easily spread through earth moving machinery travelling between properties and so on, and operators wash all machinery down before they leave a farm in an infested area.
People don't appreciate the long-term implications once it gets onto a property Chilean needle grass is very difficult to control but a little bit of thought and good hygiene between properties is going to avoid huge problems in the future.