My ds refused to eat any veg/friut from weaning umtil the age of three, depite my best efforts.
He had bad constipation as a result and I was so fed up with being seen as a lazy young mum who didn't care. I had some horrendous unfounded comments from nurses/pharmasists etc who just assumed I was feeding him crap and no veg or fruit as i couldn't be bothered.
One day (when he had just turned 3) I decided enough was enough and came over all mean mummy and served his veg first at meal times. If he ate it, he could have his mash/pots and tofu/quorn etc but if he didn't, it all went in the bin and if he was hungry later, there was friut, and if he didn't want that then tough. He starved himself at dinner time for three days, all food went in the bin... on the fouth day he got the message and ate all his veg. I continued serving the veg first for a few months, by the age of four he would eat any fruit veg that was put in front of him, and at nearly seven, still does.
I know that may sound horrible to some people, but he was the fussiest eater in the world, survivng on toast and yogurt, and he changed so quickly once he realised there wasnt a choice anymore.