Bidens pilosa

Cobbler's Pegs, Farmer's Friend at Banks, ACT

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Identification history

	Bidens pilosa	3 May 2015	BettyDonWood
	Bidens pilosa	2 May 2015	MichaelBedingfield

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Significant sighting

MichaelBedingfield noted:

5 May 2015

I have not seen this plant before around here, but am familiar with it from living up at the North Coast of NSW, where it is a problem weed. This patch is only a few years old, yet it is quite large. The weed has spread a considerable distance away from the original patch, with the odd plant or small groups of plants here and there. It seems to my amateur's experience to be a serious problem.

User's notes

The patch of plants was quite dense, about 10m long and several metres deep, along the fence.

9 comments

MichaelBedingfield wrote:

3 May 2015

This may be a significant sighting, so I want it to be confirmed. I have not seen it around here, but I am familiar with it from having lived up the North Coast of NSW. It is in the same place where I found the Cenchrus setaceus in 2010. It was totally absent then. But now there is a very dense patch, and there are smaller patches spread along the fire trail some distance away. So it seems to have spread rapidly.

AaronClausen wrote:

3 May 2015

Yuck, does this need to get eradicated?

MichaelBedingfield wrote:

3 May 2015

I don't know, Aaron, so I hope to get an experts opinion.

FranM wrote:

3 May 2015

I also have experience of this weed in northern NSW. The barbs attach easily to socks and animal fur and are very quickly disbursed and a large colony is soon established. Seeds can remain viable even after socks have gone through a washing machine cycle - evidenced by seedlings germinating in a row under the clothesline! It is easy to hand-weed and as a soft weed can be easily killed by spraying. The foliage may be frost tender here in Canberra but I suspect that the seeds would remain viable - so timing of eradication would be important.

AaronClausen wrote:

4 May 2015

Would some sprayed glyphosate do the trick?

MichaelBedingfield wrote:

4 May 2015

This plants grows rapidly and make lots of seeds. My experience of them from up north is that when you sprayed them with herbicide more would come up later. It would require a strong commitment to eradicate them.

MichaelMulvaney wrote:

4 May 2015

Michael - This may be one we need to worry about re climate change. Probably not one we would control now as it is likely to get killed by frost, but it would be good if you could keep an eye out next spring to see whether it has produced viable seed. If new growth does occur then it is one that we should give priority to control. Also it appears that weedy spoil or soil was introduced to this area, do you have any idea how or by whom?

MichaelBedingfield wrote:

4 May 2015

Michael M... Perhaps the resident on the other side of the fence has dumped some lawn clippings, dirt or other garden waste over the fence. I saw no evidence of a load of soil or other rubbish. This patch of plants occurs in exactly the same place that I found the Cenchrus setaceus a few years ago. There was no evidence of this plant back then, but now there is a sizeable patch. Also in a few years it has spread some distance. You can see how far by looking at the distribution at: http://canberranaturemap.org/Community/SpeciesDistribution/8418 So I think it has been producing viable seed. And although it may be killed by frost, the seeds must be surviving in order for it to spread so far.

MichaelBedingfield wrote:

6 May 2015

Today I revisited the area to see if this weed has spread down into the creek. Unfortunately, it has, and has spread quite a lot in just a few years.

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