Weed identification Please

Hi, I was hoping that you experts could please help me to identify and eradicte an annoying lawn weed that has appeared in garden.

We recently had two fir trees cut down about 8-12 weeks ago. Following this we then spread some topsoil and then grass seed onto the bare ground under where the trees were.

Since then, new grass has sprouted (although not very well at all, not helped by the recent heat), but also a fairly annoying, a very invasive weed has too - see pictures. The weeds (100's of them) currently only exist in the areas that were newly seeded. I am adament, that the grass seed was 'contaminated' with weed seed. The seed was purchased from Wilko's. It was their 'Luxury' blend allegedly!

I am in the process of contacting Wilko's, but given we don't have a receipt, I don't expect to get anywhere and I reckon I need to deal with this myself. However, I'm a bit of a newbie gardening and don't know how.

I thought the first step would be to identify the weed and then google it, but I am struggling with that too.

I have dug many of the weeds out carefully with a weed removal tool, but they are dropping so many seeds that I thinking I'm wasting my time and nned to do something more drastic? I have today bought some Weedol Lawn weed killer and an attachment/sprinkler device for my watering can, to apply this. No idea if this will kill the seeds as well as the weeds however?

The plants are not prickly and the seeds do not stick. I don't therefore think this is a burweed, but maybe that'll change as they mature?

The following link appears to describe a similar issue/weed and I have messaged the person concered directly to see what they did, but I've not heard. The post was almost 9 years ago, so not holding my breath.

Link found from 2013 = please help new lawn weeds!

Any help with this would be greatly appreciated! TYIA

 

Does it have a strong almost pineapple scent when you crush it.

 

My guess is the weed seed was in the topsoil. Did the topsoil come in a grab bag? If so, I reckon that's the source of the weed seeds.

 

Hi Pete, no, it doesn't unfortunately

 

Hello Hoofy, Yes it did. You could well be right. Know what it is then?

 

Swine wartcress.

 

Hi Jocko, that is almost certainly it! Thank you! Appreciated!
I will read up on this later, but maybe you've had to deal with it, and have some advice?

 

Look what I,ve got at the rear of the herbaceous border. Getting bigger every day !
Currently 1 metre tall. Probably seed dropped by bird but what is it?

 

Hi, this is definitely different to the weed I originally posted about.