I would say leave it and not worry.
my DS1 is 7 and a PITA for eating veg.....or even fruit......but I want him to learn to eat what he likes (within reason) without getting phobic about it, so now just give him what I know he will eat. makes me more relaxed, as it does him!
DS2 also does not eat any veg, but he will eat tons and tons of fruit, so I don't even care that he just has meat on his plate (he won't touch potatoes either after a severe vomitting epsiode after mash potato!). I do make gravy tho witht he veg water, so I feel he gets some vitamins, and will whiz up some veg for a spag bol sauce so another sneaky way.
for now tho, with regards to DS1, I ensure he has at least one each of the fruits that he will eat per day, plus a vitamin tablet, plus fruit juice (which also counts as one of your five-a-day)
I also remember DD1 going thro this after perviously being a superb toddler who would eat anything......I went thro years of stress with her, even driving me and her to wicked arguements about food, yet now she will try anything, and eat most things (she is almost 14), so I do think that if they start off well, they will comes back again even if you have a few 'wild-years' in the middle...
good luck, and try to relax, as an uptight mum is the worst thing you can have regarding food......and I KNOW this to my cost