Need help: Sweetheart Lychee refuses to bear fruit

[stressbaby]

Hi all,

I have a Sweetheart Lychee growing in my greenhouse in Missouri.  By following the advice (from Lycheesonline I believe) of pruning mid July, then dipping the GH temp for a few weeks around November, I have reliably gotten this tree to bloom. 

I have had one fair yield from this tree about 6-7 years ago, the first year it bloomed for me.  It must have been beginner's luck.  I've had virtually nothing since then.  Of course, this tree must be hand pollinated.  I've tried various techniques over the years, finally settling on Q-tips used like a fine tipped paint brush.  What I do is gently tap the blooms with male flowers over a black flat surface.  If I see pollen dust in the air or yellow pollen on the black surface, I'll use that pollen.  Brush a little on the Q-tip from the pollen gathered on the black surface, touch several open females, repeat.

This year I was determined to get a big yield.  The tree put out huge great blooms.  Tons of pollen from the male flowers.  I used the Q-tip technique and I'm 100% sure I had pollen on those females, because in many instances I could actually see the yellow color on the female flowers.  Work constraints require this be done early morning, but I spent 30-45 min most mornings hand pollinating.

Well, you guessed, I got nothing.  Nada.  Zip.  I must have pollinated a few hundred females.  I got a couple of dozen where the fruit started to form (I think it is the ovary that starts to swell?  Can't remember the anatomy but you know what I mean).  Half a dozen grew to pea size.  Eventually every fruit dropped. 

This tree grows very well; I have to prune it pretty aggressively in July to keep it in bounds.    I should also mention that I also have a Brewster, much smaller, somewhat of a frail little guy which is probably 8-10 years old and which has never grown well like this Sweetheart.  It's a very shy bloomer and was not blooming at the time the Sweetheart was in bloom this year.

Any ideas what I can do?  Do I need a another tree?  This is really exasperating. 

[BestDay]

I hope someone can help you.  I would assume the tree wasn't getting enough heat. But you say it's in a greenhouse and grows very well so that probably isn't the problem.

I wanted to grow a lychee but after hearing all the stories like yours I decided it wasn't worth the aggravation. I wish you the best.

Bill

[simon_grow]

Hey stressbaby, I assume your tree is potted because it is in a greenhouse, if so, I believe that it is slightly more difficult to maintain the proper soil moisture for your tree to hold more of its fruit. Also, I believe that one of the natural fruit drop cycles that occurs with a Lychees coincides with a flush so if you are pruning your tree or if you fertilize with a lot of nitrogen while your tree is holding fruit, it may induce a vegetative flush shortly after you prune and that may cause fruit drop.

Since your Sweetheart is growing do well, perhaps you can try withholding Nitrogen fertilizer for a whole year unless you start to see a deficiency. By doing this, it will slow the growth of your tree so that you may not need to prune it. Keeping the Nitrogen levels low may also help you get a better bloom next year. You may also want to try giving your tree some drought stress a month or two before you think it will flower and also slowly increase the amount of water you give your tree. If you water too much or too frequently, it may induce a vegetative flush. Good luck with your tree and please keep us updated on its progress. I would love to see a picture of your tree.
Simon

[stressbaby]

Thanks Simon!
I prune the tree once a year in mid-July.  It is not in a container, but rather in a raised bed.  I fertilize it at about half the rate of other plants, but it would be easy to cut back some.  There is some ginger underneath, and I could pull that out just to reduce competition, but it is dormant half the year so hard to think it is taking up too much of the water.
I will get a pic today and post it.

[FlyingFoxFruits]

a wise old man named Toppy (who grows this variety,  and has over 7 varieties of lychees, including over 4 separate sweet hearts) he once told me,

"sweet heart = sweet shit"

it doesn't produce worth a damn for most growers in FL.

[stressbaby]

Hmm...maybe I should just get a Mauritius...

[bsbullie]

Hmm...maybe I should just get a Mauritius...

Mauritius is a vigorous grower that may cause problems in your greenhouse.   Maybe consider Hak Ip though many believe that is the same as Sweetheart.

[simon_grow]

I think it just takes this variety a bit longer to get established before it will produce well. A friend of mine in California has a tree that produced about 2-300 fruit after it was in the ground about 6-7 years. When young or newly established, it tends to drop most it's fruit. The fruit it does produce is large, tastes great and has a small seed.
Simon

[puglvr1]

Found this article on lycheesonline...Not sure if it will work for you? I'm probably too chicken to try it,lol...afraid I would kill my tree  ...could be a last resort since the tree hasn't produced in 6 years?

http://www.lycheesonline.com/girdlingtips.cfm

[Mr. Clean]

Lychee's a known to be an unreliable bearing tree.  One person with a bumper crop of Sweethearts told me he put 0-0-50 fertilizer down in October and got a massive crop the following year.  I suggest planting a Longan.  Longans a more reliable fruit tree, with a similar tasting fruit.

[stressbaby]

I thought about girdling, but my problem is not flower production, it is fruit set (too little) and/or fruit drop (too much).
Here are pics.  If you look closely, you can still see the barren flower spikes.





In the second picture alone you can see what's left of a dozen blooms. 

Thanks for the longan suggestion, but the longans I've tried, while nice, didn't taste too much like lychees to me...more like a cantelope.

[simon_grow]

Girdling is supposed to help with fruit set and the holding of fruit. There are also chemicals you can spray on the trees to help retain more fruit but I recommend against this practice and don't have any info on it. Girdling is a good option.
Simon

[stressbaby]

OK, thanks Simon.
2014 will be the year of the girdling experiment.
Prune mid July
Girdling around Oct 1.
Chill hours first 3 weeks of November.
I'll report back!

[Mr. Clean]

OK, thanks Simon.
2014 will be the year of the girdling experiment.
Prune mid July
Girdling around Oct 1.
Chill hours first 3 weeks of November.
I'll report back!

I presume you are girdling a big tree limb; girdling the main trunk may kill the tree.  I would try the 0-0-50 fertilizer option first.

[bsbullie]

Despite your source using 0-0-50 and getting a bumper crop the following season, do you have any published evidence that this is effective in forcing lychee fruit set (keep in mind from the original post, flowering is not the issue here, its setting of fruit).

As for longans tasting similar to lychees...not even close.  Only similarity is an outer skin that needs to be pee lo ed and the flesh of the fruit surrounding a seed.

[simon_grow]

Yup, be sure not to girdle a main branch. If your main trunk splits into three main branches, you can try girdling one of the three main branches and then alternate the branch you girdle every year.

I noticed that your Lychee tree appears to be partially shaded by a banana tree and your greenhouse appears to let in about 85% of the sunlight. Lychees need lots of sun to produce fruit so making sure it does not get shaded is very important.
Simon

[stressbaby]

Actually that is 50% aluminet shade cloth.  It is necessary to prevent overheating inside in the summer, because we get to 100F in the summer.  Ventilation, shade, and misting are needed to keep temps down.

If that is important, what I could do is leave the shade cloth down until about first of June.

I appreciate all of the replies.

[BluePalm]

Yeah, my 9-10' Sweetheart was COVERED in small lychees this year (like years past). I have ONE lychee on the top of the tree. It's about to be cut down and a Makok Sapodilla put in its place.

[gunnar429]

I love lychees, but I am going to hold off a bit before getting SH...or any others for that matter.  I know they take years to get going, but i don't want to make an impulsive buy and regret it later.  I presently have mauritius and B3

[Doglips]

Good looking trees for Missouri, greenhouse or no.