| Caltrop weed- watch out for this 'nasty'
Bruce Robinson sent out this alert...
Bike-paths with broken glass or puncture-causing prickles are a serious disincentive to bicycle transport. Control of path-side prickles is essential to make good use of the investment in our path network.
Caltrop burs come from the low-lying spreading plant which is relatively uncommon at least in some areas. Mike Norman of the CTA and others have been trying to eradicate infestations of Caltrop along paths in the northern suburbs. The plants flourish in summer, and are doing well with the mild damp summer. They are seeding now, or starting to.
The caltrop plants growing beside bikepaths are often very flat-growing and a greyer green in leaves than is shown here.
Current infestations of which I am aware are.
1: CityWest, inside the railway fence along side the Principle Shared Path south of the railway line,east of the City-West station. Only two plants visible, perhaps remants from an infestation last year. Cyclists cannot remove them as they are inside on railway land, and access is prohibited.
2: Cottesloe: A big infestation on the slope above the PSP at Grant St Station, just south of path from the station to the pedestrian crossing. I removed about half a rubbish-bin of plants this afternoon, but only completed about half the job (results in the rubbish bin just where the bikepath rejoins Curtin Avenue). Some plants have already dropped their seeds, so the site will have to be monitored for a number of years. Caltrop is quite rare in Cottesloe, as far as I know, and it looks like this infestation may have been introduced during works associated with the path construction, perhaps.
Removal of the plants is essential, as soon as possible before the burs are liberated. Later inspection for new germinations this year is important, and inspections next summer for germinations from burs left this year after the plants were removed, and from those plants missed.
| Caltrop
Tribulus terrestris
What does caltrop look like?
Caltrop has fine fern-like leaves and grows flat against the ground. The leaves are usually a dull greyish-green colour. The tiny flowers are yellow with 5 petals. The woody prickles are similar to doublegee, however caltrop only grows in summer and doublegee grows in winter and spring. Doublegee has a broad leaf similar to English spinach.
What damage can caltrop cause?
Heavy infestations after summer rain can produce an abundance of sharp spiny burrs, which make it very uncomfortable for people and animals alike. It is also a nuisance around farm buildings, townsites, railway yards and recreation areas because of the burrs.
When am I likely to see this pest?
Summer.
What if I find caltrop?
Small numbers of plants can be eliminated by hand grubbing, or if there are only a few plants on a firm surface, the quickest method of removal is to cut through the central tap root. The plants and seeds may be placed in a bag and disposed of in a bin or they can be dried and then burnt, if permitted by local council bylaws. Carefully pick up any of the spiny seeds that fall from the plant.
Where do I seek advice?
Contact the local shire or town council
Department of Agriculture fact sheet (pdf) |
