We're going to have to ask the usual things, Kelley! Do you know what the pH of your soil is? Is there a possibility that you've been watering too much? How long has it been planted in its present location? What kind of fertilizer do you use and what is your schedule for applying it? Did you add anything to the soil when before or when you planted? (That's a trick question, lol.)

Right off the bat, I think that it is important that you pull all of the weeds and grass away from the tree...and anywhere near it. Apply a 2 to 3 inch layer of mulch (wood chips or pine straw) to slow the weeds down. Don't pile said mulch up against the trunk but be generous in in how wide a skirt you give the tree.

Please don't be tempted to use RoundUp to get rid of the weeds. Not only is your tree too young for that kind of exposure, but RoundUp , once it enters the root system of the weeds you've sprayed it on, can co-mingle with other roots in the rhizosphere. That looks to be about 5 minutes of weed pulling and hoeing. Once you get the mulch down, you can keep up with the weeds easily.

Everything rhizo said. Your tree appears to be suffering from lack of nitrogen. You don't mention how frequently you're fertilizing it, or with what kind of fertilizer. Citrus need more nitrogen than other fruit-bearing trees, so you'll want to fertilize it regularly with a fertilizer especially formulated for citrus that also includes micronutrients. At least 3 to 4 times a year.

Patty S.

get rid of the weeds.

needs some fertilizer.

Florida has Phytophera issues; what is the rootstock of your grapefruit; and what type grapefruit is it?