Spraying of roadsides on State Highway 77 between Ashburton and Methven is due to start this month in a move to prevent the plant pest black grass becoming established in New Zealand.
The use of selected herbicides in areas of risk along the route is part of a plan to monitor the area and eradicate any black grass plants which may grow following the spilling of contaminated seed in July.
The plan has been developed by the Ministry of Primary Industries, Federated Farmers and the Foundation for Arable Research (Far). It will involve spraying at-risk areas at least three times in the first year, five times in the second, and three times in the third year.
The whole route will be walked by people with the skills to identify the plant pest. The estimated budget is $400,000.
The emphasis was on preventing the establishment of a plant pest, rather than on blame, when farmers along the route met in Ashburton recently.
About 20 farmers who live along the route were updated on the plan.
Grass seed was spilt in July, when it was being moved by truck between Tinwald and Methven. It was potentially contaminated with a small quantity of viable black grass seed.
Black grass (Alopecurus myosuroides) is a serious invasive weed of winter crops in the UK and Europe, where it has developed resistance to many herbicides. It competes with crops for nutrients, light, water and space and reduces yields.
David Yard, a response manager with the ministry, emphasised that the ministry, the industry and landowners were all involved in keeping the black grass from becoming established.
It was estimated 2100 black grass seeds were lost along the 40.2km route.
While this was only about an egg cup full, one black grass seed was one too many, Mr Yard said.
''The Ministry of Primary Industries believes there is a high chance of eradicating black grass before it becomes established,'' Mr Yard said.
Far chief executive Nick Pyke told farmers about 80% of black grass seed germinated in autumn and very few seeds were likely to geminate in the spring. The seed would survive for two to three years relatively easily in both cultivated and uncultivated areas.
Black grass was similar to meadow foxtail, which would be flowering at present. The black grass seed spilt would not be flowering yet. It had also been confused with timothy, Mr Pyke said.
- Anyone who thinks they may have found a black grass plant should contact the Ministry of Primary Industries on 0800 80 99 66.
- Maureen Bishop.