Agree with PP.
I'm also wondering if some of his food dislikes might be related to the textures of the foods? We went thru a lot of texture aversions here and are out the other end, mostly, but I've got a kid who still won't eat eggs in most forms (too slimy, except for hard-cooked, and then not the yolk b/c it's "powdery") and only just decided to like mushrooms - IF they're portabellas.
The other one used to drink rice milk by the quart but won't touch it now b/c she's aware of the rice suspension in the liquid.
I did find that getting the kids involved in the selection and the preparation of food was helpful. Even if they didn't eat the finished meals, I knew they'd had some tastes of what we were making along the way: a bit of carrot here, maybe a bits of a green bean or a thin slice of cucumber to taste a dip, maybe a small bowl of dip or dressing they ate with a spoon, but since we'd made it I knew what was in it.
Will he eat applesauce? Dead easy to make at home, and he can help.
I got them to try greens by having them pretend they were bunnies. Both of them ate it up (pun intended!).
And they were more apt to eat a salad they'd helped prepare, or a sandwich with lettuce in it that they'd done some of the work to make for us.
With Natalie we played the "Don't you eat that!" game, in which she would look at her plate with an expression of distaste and we would coax her to NOT eat it, to not even TRY it. It is a testament to her contrary nature that she fells for it EVERY TIME and she STILL DOES!!! (She's almost FIVE now!
)
Keep the snacks healthy, offer them throughout the day, maybe when you're having a snack offer him one or two bites of yours - and make a point of eating things like apples and carrots and maybe beans or meat or other high-quality protein snacks.