It looks like contamination with aminopyralid or clopyralid, used on grassland to kill broad leaf weeds. Unfortunately if the grass is then used to make silage the weedkiller survives passage through the horse/cattle and ends up in the manure which is sometimes sold to commercial compost operations leading to contaminated batches. The RHS have an information page on weedkiller in manure.
I'd write a letter to Wickes with pictures of the plants stating that you suspect they have sold you a contaminated batch of compost and ask for a refund.
I agree with @Pete.8 and @Dovefromabove - they have been in contact with weedkiller. Had a problem exactly like that in NZ when dairy farmer neighbour sprayed his gorse! Luckily in that particular field we only 1,500 plants!! Lost that crop. Tomatoes are good for resealing and starting again. You could try lopping off the tops.
I guess it's v hard to proove that dodgy toms are anything to do with the compost. There are many other possible options. I had some very hit and miss (mostly miss) compost and manure from Wickes last year. It's cheap and they are one of the few big generalist stores that do big bag delivery. You gets what you pay for.
After many followup emails, Wickes refused to give any refund or replacement. Their supplier completely refused any contamination despite the photos.
Anyway i won't be ordering any compost from them. Tbh i am scared of buying any compost now from anywhere.
There has been a lot of talk about it in organic circles.
Don't be afraid, there is a simple test, buy some new compost.
Then do a control test.
Using a cheap variety of pea or bean seeds, sow three small pots using a good quality seed compost.
Then sow three test pots, with a mix of half the good quality seed compost, half the new compost.
Then compare the results.
If after they have 3 true leaves the ones in the new compost mix show signs of cupping, distortion or thickening of the leaves, it could indicate it is contaminated with herbicide.
If there is no difference between the test and control, the compost is good to use.
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I'd write a letter to Wickes with pictures of the plants stating that you suspect they have sold you a contaminated batch of compost and ask for a refund.
Anyway i won't be ordering any compost from them. Tbh i am scared of buying any compost now from anywhere.
Don't be afraid, there is a simple test, buy some new compost.
Then do a control test.
Using a cheap variety of pea or bean seeds, sow three small pots using a good quality seed compost.
Then sow three test pots, with a mix of half the good quality seed compost, half the new compost.
Then compare the results.
If after they have 3 true leaves the ones in the new compost mix show signs of cupping, distortion or thickening of the leaves, it could indicate it is contaminated with herbicide.
If there is no difference between the test and control, the compost is good to use.