Probably some type of orange. Could be a grapefruit.
Fertilizer and not too much water will help to regreen the leaves. An orange, in good health should be blooming now, unless it is a Valencia; and I am not conversant with that variety bloom time.

Awesome! Thanks for the prompt reply.

Any idea what type of fertilizer to use and how much?

Also any idea how old this tree is? Its about 5.5-6 ft tall.

Looks more like a grapefruit or pummelo hybrid (such as Oroblanco or Melogold). Oranges do not have such pronounced winged petioles. Do us a favor, take a photo of the bottom of the fruit. If it has a fairly pronounced dimple or indentation, it is an Oroblanco grapefruit hybrid - a very nice citrus cultivar (cross between a sweet Siamese pummelo and the March grapefruit.) Tree has probably been in the ground for 2 to 3 years, possibly more if it wasn't well fertilized, but it looks pretty healthy, despite the chlorosis. I would try to ask the previous homeowners what the cultivar is, and when it was planted. That way you can stop guessing.

Use a high quality fertilizer formulated for citrus. The NPK ratio should be as close to 5-1-3 as possible (the ratio, not the numbers), along with a full complement of the micronutrients. I would try fertilizing now, but don't be surprised if you don't see results for a bit, is your soil temps are cool. It may take some warming or both air and soil for the nutrients to be taken up by the roots. And John, mature Valencias are blooming now in my area. Late winter/early spring.

Patty S.

Here's some pictures of the bottom of the fruit. It has a small indentation, nothing spectacular.

Thanks for the fertilizer recommendation, i'm going to look up some brands tonight.

Also, I noticed that the tree drip line is a little past the edge of the basin that was dug for the tree. Is that something that I might want to widen by a few inches so that its back within the drip line?

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The only orange with a petiole like that is the Seville sour orange. And the fruit looks more like a hybrid pomelo.

Have you done the simple leaf crush test? Crush a leaf and smell it; it should give you a better idea of what type citrus you have.

Okay, could be the Oroblanco's "sister", Melogold. This is the one distinguishing feature between the two (they are very difficult to tell apart, tree to tree, fruit to fruit.) Probably is. They are are coming ripe, now, so if you think the fruit is ripe enough, pick it and eat it, and you'll have your answer. They are as excellent as Oroblanco.

Patty S.

Here is a link that might be useful: UC Citrus Variety Collection: Melogold

So I did the crush test and the leaves smell extremely 'lemony'. Another thing I noticed were short thorns at the base of the leaves. Included a picture of them. Think the fruit is ripe enough to cut and taste at this point?

You might try a gentle scratch & sniff of the peel - that should give you an even better idea...

So I went ahead and had to cut it open. Looks to be a grapefruit!

Lovely! Could be Rio Red or Ruby Red. Mine are not quite ready. How was the taste? Lovely!!

Patty S.

Try adding some Epsom salts around it. It may be winter chlorosis, that is sometimes fixed that simple thing. Go light.