I'm pretty sure that's either a wandering oilseed seedling. or some sort of wildflower/weed as I've seen it in meadow grass around Glasgow x sorry no idea what it's called, but I've also never heard of a tayberry :) new one on me, I'm off to look them up :)

Certainly not Tayberry - looks like Rapeseed?

Looks like Charlock Mustard, Sinapis arvensis L., to me pull it out wont hurt the roots of your Tayberry at all for you to do so.

Your tayberry should look very like a blackberry shoot, so if it still hasn't come up, I'd suggest the root may not have had a growing point or bud on it. If you know someone who has one, it's very simple to layer the growing tip of one of the canes and then cut it off when well rooted. This is the best way to start it off, moving it in the autumn or spring.

Good point Bertie...

My thought was a mustard or rape - either way not deep rooted so pull it out before it sets seed.

Following on from Bertie's point I'm not seeing any Tayberry growth in any of the photos.

http://www.thewesternisles.co.uk/wildflowers/charlock.htm. Interesting plant :)

Thanks everyone! I pulled it up, and now my tayberry is growing nicely from where it was! =) x