Juliemango,
If you planted the rambutan from seed there is the chance that you will get a male plant and no fruit. If its a grafted plant with hermaphroditic flowers you should get fruit no problem.

There are a variety of possible problems that your sugar apple and star fruit could be suffering from. How deeply did you plant these trees? They should not be planted any deeper than they were grown in the pots. I usually plant them a few inches higher than they were in their pots. I also never amend the soil before I plant and my soil is pure sand. My trees do very well because I mulch and fertilize often. Your trees might also be getting too much water and suffering from root rot. The problem with adding top soil and manure into the hole when you plant is that it supposedly encourages the tree to be root bound so its not recommended. Since you are in FL you should have no problem just planting these trees into the ground without any amendments.

Your kari might have dropped all of its flowers because it was too small to support any fruit. I have seen it with many star fruit trees. They load up tons of flowers but when they are young they will drop them all. It might also be from lack of water or too much.

How often do you fertilize? You should fertilize monthly with a small amount of fertilizer. I also recommend spraying every few weeks with some micronutrients.

The sugar apple probably also lost its flowers because the tree was small and it set fruit.

Do not dig them up and put them in pots. If you can dig them up and make sure they werent planted too deeply them replant them somewhere that isnt amended with top soil and compost. If you do have to mix with top soil or manure you should do it atleast with 50/50 of the surrounding soil so it wont encourage the roots to become rootbound.

If you do replant them into the regular soil you should make sure to water them regularly for the first month or two then after that make sure they get water 1-2 times a week until they are well established. Mulching is very important but make sure to not let any mulch touch the trunk.

Thanks for the advice, murahilin. Would you suggest spraying the leaves with a weak solution of miracle gro, or would wetting the leaves encourage fungus?
I notice the star fruit is blossoming again. Would you suggest that I remove the blossoms to encourage vegetative growth?

Leave the blossoms on the starfruit until the little fruit form then you can pick off the fruit.

You can spray it with some miracle grow and it wont encourage fungus. Try to spray early in the morning or late in the afternoon just not midday. You should spray your trees once a month or so. I prefer to use non chemical fertilizer sprays instead of miracle grow though.

Don't use Miracle Grow. I've learned from a very good source that anything containing chlorides can lead to rambutan decline. Stay with organics.

i have similar issues with my atemoya, very few leaves, yellowing, burning of tips etc. i think it needs a good prune next season. my KM sugar apple is very healthy looking though.

our soil here is sand, no nutrients. every few months or so i buy like 10 - 15 bags of compost from HD and put it around my trees, i planted all of my trees on a slight mound. the compost washes into the soil pretty quickly.

i am going to try to stay away from granular fertilizer, i hear they can burn roots and add to the problem.

Sugar apple is deciduous..meaning it loses its' leaves at the end of the growing season. I had this happen to all 5 of my sugar apple and atemoya when transplanted...don't worry it will come back just continue watering the first couple weeks very well. Someone else on this site gave me this info a while back and it saved a lot of frustration...good luck

Jay,
Do you think the same thing goes for pulasan? I never use the chemical stuff anyway so I guess it doesnt matter.

Boom, I dont think i've ever used granular fertilizers on any of my trees are they are doing quite well. I really dont think there is any need for them even in FL. The organics work quite well. How often do you fertilize your trees now?

mikesid,
Did your trees produce well this year?

I'm going on that assumption and treating the pulasan as I will the rambutan. No sense tempting fate any more than I already do.

murahilin, everything that I had pollinated produced well and the ones I didn't only produced a couple of fruits. I still got a couple out there with fruit on it. Trying to keep some on there as long as possible. My Kari starfruit always produces like crazy. I got some early fruit by girdling a couple of branches. It always seems to be producing.

Boy, I wish someone had told me a few years ago that the sugar apple is a deciduous tree. That was one of the first things I planted and when all the leaves fell off I got rid of it and planted a carrie mango in it's place. Oh, well, I love my Carrie and I am trying again with the sugar apple.