Winning the war on weeds

Caltrop – a prickly subject for Urban Councils

Caltrop -coming to a nature strip near you.

There are few plants that can germinate -set flowers in 3 weeks and produce viable seeds within 5 weeks. There are fewer that keep on growing, flowering, and seeding, again and again from the same plant. And then even less, that given the right conditions, can claim 4 or more separate germinations all in the one growing season from Oct to April in South Australia. Caltrop qualifies hands down as a ‘WON’ – a Weed of National Significance.

In our attempts to contain and control this troublesome weed, can the application of modern technology give you a new advantage?
Caltrop has all the characteristics of a troublesome weed in pastoral and cropping land, vineyards, recreational areas and given the right conditions, could be growing in suburban nature strip near you.  At this time of year in urban Adelaide you may not have far to travel, before you are likely to encounter the consequences of Caltrop.
Why is that?  Well it loves our Mediterranean climate, from where it originated, being inadvertently carried into Australia, like many of our nuisance weeds. It is an opportunistic weed that will take advantage of bare and open ground in which to grow.

Aggressive Survival Objectives

Caltrop produces large numbers of sharp woody burrs that when mature, segment, and easily drop off. Each one has atleast 3 spines or more, and no matter which way it falls onto the ground it will always have one or more spines sticking-up, just waiting for you to step on or ride-over and carry away. What an effective way of dispersing its seeds. Never mind about the pain caused to you or your pet dog or cat, or the inconvenience of a flat tyre, just when you were planning a decent bike ride.  The plant has just one objective in mind – survival of the next generation – and that’s all it cares about. Very smart indeed.

Caltrop – not the cyclists friend

So what is being done by whom and what can we learn from any successful battle campaign that can be applied to this “war of weeds” regarding Caltrop?

State and local government authorities are well aware of the plant and the problems it causes. The Natural Resource Management Boards (NRM), and Council officers have, to varying degrees, annual control programs in place. But are we winning the war? Is the amount of Caltrop increasing or decreasing? Nobody is really sure.
In recent times fitness campaigns have been encouraging us to get out and walk more. There has been a rapid increase in the popularity of recreational bike riding. People are out and about. Suddenly people are discovering Caltrop plants, which before, they may not have been aware. We are encouraged to take an interest in our community. It is now easy for us to report things directly to Councils on –line, hence Caltrop reports to Councils have increased. But is the spread of Caltrop increasing, decreasing, or just the same?
The answer is that without accurate data we don’t really know.

Modern Warfare

That’s where the application of modern technology could start to make a real difference. Having good intelligence, information, data, accurate mapping and an action plan are critical. Just like conventional warfare, without information and measurement, how do you know that you’re winning or losing any campaign?
UrbanVirons have in conjunction and co-operation with Councils manually mapped Caltrop locations and infestations for many years. This year in conjunction with ESRI GIS ,Caltrop is now being plotted electronically in the field. This information is then uploaded and transmitted direct t to our server, and then relayed to Councils’ GIS mapping systems.
Based on the Australian standard for GIS plotting and recording, latitude & longitude, plant description, size of infestation by m2 or polygon shape , date recorded, method of treatment, operator ID are all recorded.  A photograph can also be taken.

Strategic Advances

This information can then be downloaded in layers files directly to Councils and this means that as the season progresses each separate germination can be recorded. A progressive seasonal picture emerges. Each subsequent year more information is added. Over time real factual data can be analysed to show :
  • · areas of infestation
  • · how wide-spread
  • · are they increasing/decreasing
  • · number of germinations
  • · effectiveness of control campaigns
  • · cost/value analysis and benefits etc
NRM Boards will be able to collate findings from all participating Councils to get a State wide perspective. This linked to comparative interstate authorities will give a national picture. Accurate and timely information is the key to being effective
Caltrop is certainly a community nuisance.  For Councils it is a prickly subject. Now, through the adoption of modern technology, peer Council commitment, and a co-ordinated approach we may well stand a real chance of winning the war on Caltrop.