Does anyone know if I can bring fresh blueberries in my carry-on luggage from Orlando to San Juan? Or who I would call to check?

Check the airline website for the US Department of Agriculture rules which are very strict about fruits, vegetables or garden products of any kind. Even though PR is a US territory, I would be amazed if you could bring such things in even from the US. I know for a fact that you cannot do it the opposite direction.

Yes you can. I bring sandwiches and fruit (usually bananas and apples) all the time for my son. It's coming back to the U.S. that restrictions apply depending on the country of origin.
I just looked at the list of prohibited items on the TSA web site and fruit (except jarred and canned) is not listed.
You can always call the airline you're flying or email the TSA with your question if you're concerned.

You can bring fruit on to the plane and since there are no customs or agricultural checkpoints that you'll have to pass through once you get off the plane in San Juan you won't have any problems their either.

If you are flying on to another destination (such as one of the Caribbean Islands) you probably won't be able to bring the fruit into that country.

As was noted earlier, bringing fruit, vegetables and/or plant material into Puerto Rico via airline is not a problem.

Taking fruit/plant material in the opposite direction, from PR or the USVI, _is_ a problem.

You can view this USDA document ... http://permanent.access.gpo.gov/lps3025/topfprvi.pdf ... for the restrictions regarding import of plant material from the Caribbean to the US mainland.

// Ray

Yep. you can't take fruits out of PR say into the US. I forgot I had some apples in my back when we returned from a cruise in March. heading from PR to Chicago, when we went through security they took them.