Posted: 23/08/2014 at 10:52
(I feel like Dr. Who now) A few years ago there was a piece on Gardener's Question Time about horse manure that was killing people's gardens. It was caused by residues of weed killer (presumably for killing ragwort) that had passed through the horse's digestive system.
I don't know much about weed killers, but would NEVER personally put plants treated with it on the compost heap, just to be on the safe side. When I use 'Weed and Feed' on the lawn, the packet says not to compost the first 2 or 3 cuts of grass. I know some weedkillers are neutralised on contact with soil, but I still would not feel happy about this.
Have just looked through my notes on what one can and cannot compost; there is no mention of weedkiller. So am going to email Garden Organic and ask them.