Friday, August 25, 2006

Fighting the Flag

At this time of year Cottesloe Coastcare volunteers spend many hours carefully hand weeding at our various project sites. Environmental weeds and garden plant escapees are huge problems in remnant bush sites, especially in metropolitan areas. Weeds can quickly over take the local native species, become dominant and local plant diversity can be lost forever. If you want more information on weeds click here to see the excellent Western Weeds website.
Dumping of garden rubbish in bushland and on the foreshore is diminishing but unfortunately it still happens. At Grant Marine Park in North Cottesloe we have virtually eliminated Blue Lupin and we are making excellent inroads with a garden weed escapee - white daisy or Michaelmas Daisy. We made a decision three years ago to have a 'No Tolerance Policy' towards the weed Pelargonium capitatum (rose pelargonium), but we still have a long way to go before we eliminate it from the area. Another weed which causes us lots of grief is Ferraria crispa commonly known as black flag. Frauke has written the piece below about black flag but as she and her husband Keith have set off to ride their bikes to Adelaide I will put this post up for her. I hope the winds continue in the right direction for Frauke and Keith!

Fighting the Flag
Above ground, it looks so innocuous – just another sword-shaped blade of grass? Nothing to worry about? You try to pull it out – it doesn’t come easily, it’s obviously well rooted. Then you dig around it, deeper into the soil – there, a solid, light-brown corm, like a small potato.
If you are lucky, it will still be attached to more corms – up to 12 hanging on underneath the first one, like pearls on a string! And each corm has the capacity of growing several healthy plants. And the strings of corms don’t just go vertically, they spread sideways, too – in some sandy patches you see a whole colony of them, neatly packed into the earth – hundreds of them. In evolutionary terms the columns of corms are thought to be half way between a corm and a rhizome (Du Plessis and Duncan 1989).

We have several patches in our dunes where this South African invader Ferraria crispa, or black flag has appeared – the worst possibly near the pathway at Mudurup Rocks where the use of a specific herbicide mix has not produced the result we were hoping for yet and has killed several of our indigenous coastal plants. The very smelly flowers attract flies. Black flag has found growing conditions here simply ideal and that it has developed vigorous growth patterns. In its home land it is an endangered species. Black flag is so successful here that it poses a real threat to our native plants – it kills them mercilessly and is extremely difficult to eradicate. It’s like a bulbous cancer with metastases in unexpected places, moving like a subterranean reptile.


A small group of Cottesloe Coastcarers has made a concentrated effort to fight the flag at Grant Marine Park – you may have seen them on their knees, unearthing bags and bags of corms, sieving shovel after shovel of sand – and after hours of hard work the ‘cleaned’ area looks pathetically small! Is it worth it? Will they conquer the aggressor? Have they saved some of our native battlers? Only time will tell.

To see more photos click here. You can click on any photo to enlarge it.

(Text by Frauke)

2 Comments:

Blogger Dani said...

Hi Robyn

As you mentioned, black flag are a problem in many bushland areas around Perth - including Shenton Bushland (which I am involved with).

Unfortunately, we are not able to disturb the soil to remove the corms - so the weeds are spreading through the bushland.

Fortunately, we have support from Urban Nature (department of environment) - who are testing out chemical treatments - hopefully we will have one soon!

6:46 am  
Blogger Robyn said...

Thanks so much for your comment Dani. One of our main aims of the blog is to get some dialogue going on subjects which are of great concern to us all. For three years we have had a herbicide contractor spraying/wiping one area which is severely effected by black flag - using the regime described in 'Bushland Weeds, a practical guide to their management',(Brown and Brooks 2002). Unfortunately some collateral damage occurs even with careful spraying/wiping. There has definitely been some progress and this echoes the experience of other groups where spraying has been carried out for several years. Some experimental work is being done using 22DPA I understand and Black Flag is the subject of a PhD thesis being undertaken at present. Hopefully we will soon learn more about controlling this weed which is of such concern.

11:02 am  

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