Encouraging acerola fruit set

[KarenRei]

So, I've finally figured out the recipe to making my acerola flower: fertilize well, calcium-rich / higher-pH soil, good root aeration, significant dry period, then water and prune (no clue why pruning encourages flowering, but it sure seems to).  Right now my acerola has more flowers on it than it's ever had on it in its whole life put together.  Yet at least so far I'm not sure if I've gotten any fruit set. Are there any good tricks for that?  I've done some trying to pollinate with a sponge paintbrush, some tree shaking, and last night I have it a heaping serving of potassium sulfate, hoping that will help.

I love acerola, and they're quite good for you too, so if even a small fraction of these flowers set fruit, I'll be quite happy 

It's weird that I never seem to see any pollen grains.  I can see the anthers in the flowers and they're bright yellow, but no yellow "dust" ever seems to come off of them.  I'd break out the microscope but the eyepieces are a bit messed up at the moment...

[luketrollope]

Hi Karen let me start by saying I enjoy your posts you being in Iceland and all.

I imagine you are growing in a greenhouse or hot house and your problem would be not having the right insect pollinators.

Could you let some bees lose in the greenhouse?

Check this link for more info

https://www.researchgate.net/publication/277323828_Lessons_in_Production_of_Acerola_from_a_Single_Tree_Flowering_Pollination_Fruiting_Harvests_and_Pests

As a side note I have an acerola (Malpighia emarginata) tree here that only flowered very rarely once every 2nd year or so until the big shade tree that was shading it fell down since then it has been more or less continuously flowering for the last 8 months about 4 flowering's the point being they like full sun to flower well and how plants sense an "opportunity"  in the canopy cover.

Anyway good luck they are a great fruit and an excellent small backyard tree.
 

[KarenRei]

Hi Karen let me start by saying I enjoy your posts you being in Iceland and all.

I imagine you are growing in a greenhouse or hot house and your problem would be not having the right insect pollinators.

Could you let some bees lose in the greenhouse?

Unfooooortunately, my plant grow area is part of my living space, so I don't think it would be an especially bright idea to unleash a swarm of bees!    I've tried pollination with the foam paintbrush, but maybe I should go to an art shop to get a fine horsehair one?  (I have some hair paintbrushes, but they're larger than I'd think one would want to use).  I'm thinking about ordering a pollination tool, but it won't get here for quite a while even if I do.

Thanks for that link; it sounds like there's no fruit set without some sort of pollination, so I guess that means I don't get to slack off on that 

As a side note I have an acerola (Malpighia emarginata) tree here that only flowered very rarely once every 2nd year or so until the big shade tree that was shading it fell down since then it has been more or less continuously flowering for the last 8 months about 4 flowering's the point being they like full sun to flower well and how plants sense an "opportunity"  in the canopy cover.

I did add some more light in January, and I plan to add yet another one this summer.   So I'm sure that too contributed to how dramatic this flowering is; it's clearly quite happy.  Just need to translate flowers to fruit!    More than just a few at a time like I got in past flowerings.

Do you think misting would help or hinder fruit set?  I normally mist daily.

Anyway good luck they are a great fruit and an excellent small backyard tree.

I know, aren't they?    The first time I tried them it was a "Hmm, this is decent... fragrant taste, mildly sweet, but nothing spectacular".  But I've developed a craving for them over the years    I think my body learned to associate the taste with their nutrient content.  Great out-of-hand fruit.