Post by Clue on Jun 22, 2021 18:26:43 GMT -5
Cherimoya (Annona cherimola) is a really interesting fruit. Despite being in a very good subtropical climate here, I rarely see the fruit for sale and they don't seem commonly grown here in the Bay Area compared to citrus and avocados. Sometimes called custard apple (which is also used for other Annona), the ripe fruit have a creamy texture with a sweet tropical flavor that I'd describe as mostly banana and pineapple with a hint of pear, plus a fragrance somewhere between pears and green apples. The exterior can vary a lot, but the thinn-ish skin is green with either flat depressions (that look like someone repeatedly pressed their thumb into the fruit), bumps, or tubercles.
When I was in high school, a local Vietnamese grocery store started selling cherimoya fruit regularly in the winter and spring. I bought some small ones one year on a whim and really liked them, but they were expensive! I decided to try growing the seeds from those fruit; some internet searching said cherimoya grow decently well as potted plants and that the fruit quality from seedlings was generally very good (unlike very heterozygous fruits like avocado and apple which do not grow true from seed). After a while, I had a few saplings on my patio but they really failed to thrive. When they seemed to be on their last legs, I wrote it off as a loss and planted the 3 surviving saplings in the ground, fully expecting them to die sometime before leaving home for university. While I was gone, the saplings crawled along for a couple of years, then all of a sudden had a massive growth spurt. I thought it was amazing when they reached chest height and I saw flower buds for the first time. Now, about 8 years after I started the seeds, these guys are truly trees now! I got the first batch of fruit at the end of 2020 to the start of 2021, although the first fruit could have been a year earlier if I was home to pollinate the flowers (more on that later), and probably even earlier if these trees weren't generally ignored!
December 2017 - this is the oldest picture of my cherimoyas. I think I took this one since one of the saplings finally had a strong central leader growing at a good pace. It still must have been shorter than me though.
June 2019 - 2019 was the first year I noticed flower buds. They are very inconspicuous though! I was not home to pollinated the flowers or even see them open. The whole tree habit at this point is very spindly; I think my parents called it the Seuss tree since it had these big funny fuzzy leaves on otherwise very thin stems.
late May 2020 - 2019-2020 was a big year. The tree set lots of branches in 2019 and lots of flowers in summer 2020.
September 2020 - I spent much of June and July figuring out how to pollinate cherimoya for the first time, and apparently it's not too hard. By September, the fruit are halfway to maturity and about golfball sized. I put twist ties on the flowers after I pollinated them to monitor pollination success, and from my experience hand pollination is very important! I found a single fruit without a twist tie, but a spontaneous fruit is less likely than a twist tie just falling off. Pollination wasn't always successful but well over half of the flowers I pollinated formed fruit.
Also the tree is actually quite attractive once it's leafed out properly. In the winter, cherimoya will defoliate and drop the apical buds after light frosts. If it's a particularly mild year without frosts (like our 2020-21 winter), the leaves will stay on until the tree starts budding out in April/May. The lower branches naturally form an espalier shape not unlike Coffea arabica. This tree receives no irrigation other than whatever winter rainfall we get and tolerates very high temperatures (no issues with heat waves in excess of 90 F in 2020).
December 2020 - the first fruit was an early windfall that cracked while it was still on the tree. They're small fruit but considering the trees are completely unirrigated I'm still impressed. Lots of seeds but the flavor is very good. Had to find a very small spoon to scoop out the flesh. You do not want to eat the skin or the seeds, everything on this plant besides the white flesh is poisonous!
January 2021 - the bulk of the cherimoya were ready in January. I'm not sure if there's a better way to figure it out, but I let the fruit pick themselves - if I fiddled around with the fruit for a bit and it fell off the tree, I'd take it inside to table ripen until the side yielded to gentle pressure (like an avocado), which generally took a few days. The largest of the bunch fit very nicely in my palms, and are maybe 3/4 the size of the small ones I bought at the grocery to start with.
April 2021 - like I said earlier, the winter of 2020-21 didn't have any significant frosts for us, so the tree was actually still covered in leaves in April when the branches are usually completely bare. The apical buds still have a tendency to fall off over winter, which seems to be part of the natural branching structure.
June 2021 - Despite keeping most of last year's leaves through April, the tree will still defoliate as the new shoots grow, so any leaf on the tree is no more than a year old.
So what's the deal with hand pollination? Well, despite having very fragrant flowers (they've got the same green apple/pear scent the fruit do), apparently cherimoya are only pollinated by either beetles or wasps that aren't found outside the plant's native South/Central America. There's a few practical issues with hand pollinating: (1) The flowers are incredibly inconspicuous. They're green and while pendulous, the huge leaves cover them so you can't see them even when standing right below a branch. Maybe you could find them by smell, but my sense of smell is very poor so I can't. The major leaf flushes also come at the same time as the flowers. (2) The flowers are protogynous, so an individual flower has 2 distinct phases where first the stigma is receptive, and only after do the anthers release pollen. With some experience, it's easy to tell the phases apart: the first day a flower is open, the three fleshy petals are barely open, spread mostly at the end. This is the female phase. The next day, the petals are widely spread, and in the evening when I do my pollinating, the anthers and pollen will fall when manipulated with a brush, which I collect in an envelope and apply to any flowers in female phase. The day after the male phase (the third day), the petals will be dry and brown, falling away from the ovary. If not successfully pollinated, the ovary and pedicle will fall on the fourth day. The good news is that cherimoya is self-compatible, so you don't need pollen from a separate tree. (3) The flowers are unpredictably placed. Flowers will grow on last year's wood, this year's wood, and even right off of the main trunk. Now that I need a ladder to work many of the flowers, this makes finding the flowers even more difficult.
I've got a few plans for my trees in the future. This winter I'll have to prune the tree a lot since even the 12 feet height it is now make it hard to work with. Apparently, down in Southern California they prune to get the trees to grow as densely as possible to increase the odds of spontaneous pollination. I'd also like to try eating atemoya - this sugar apple x cherimoya hybrid is variably rated, some say it's not as good as cherimoya, some say it's better. But the Geffner atemoya variety is supposed to set fruit well without hand pollination, so if it's tasty and I could find some scions it wouldn't be hard to graft them onto cherimoya branches.
When I was in high school, a local Vietnamese grocery store started selling cherimoya fruit regularly in the winter and spring. I bought some small ones one year on a whim and really liked them, but they were expensive! I decided to try growing the seeds from those fruit; some internet searching said cherimoya grow decently well as potted plants and that the fruit quality from seedlings was generally very good (unlike very heterozygous fruits like avocado and apple which do not grow true from seed). After a while, I had a few saplings on my patio but they really failed to thrive. When they seemed to be on their last legs, I wrote it off as a loss and planted the 3 surviving saplings in the ground, fully expecting them to die sometime before leaving home for university. While I was gone, the saplings crawled along for a couple of years, then all of a sudden had a massive growth spurt. I thought it was amazing when they reached chest height and I saw flower buds for the first time. Now, about 8 years after I started the seeds, these guys are truly trees now! I got the first batch of fruit at the end of 2020 to the start of 2021, although the first fruit could have been a year earlier if I was home to pollinate the flowers (more on that later), and probably even earlier if these trees weren't generally ignored!
December 2017 - this is the oldest picture of my cherimoyas. I think I took this one since one of the saplings finally had a strong central leader growing at a good pace. It still must have been shorter than me though.
June 2019 - 2019 was the first year I noticed flower buds. They are very inconspicuous though! I was not home to pollinated the flowers or even see them open. The whole tree habit at this point is very spindly; I think my parents called it the Seuss tree since it had these big funny fuzzy leaves on otherwise very thin stems.
late May 2020 - 2019-2020 was a big year. The tree set lots of branches in 2019 and lots of flowers in summer 2020.
September 2020 - I spent much of June and July figuring out how to pollinate cherimoya for the first time, and apparently it's not too hard. By September, the fruit are halfway to maturity and about golfball sized. I put twist ties on the flowers after I pollinated them to monitor pollination success, and from my experience hand pollination is very important! I found a single fruit without a twist tie, but a spontaneous fruit is less likely than a twist tie just falling off. Pollination wasn't always successful but well over half of the flowers I pollinated formed fruit.
Also the tree is actually quite attractive once it's leafed out properly. In the winter, cherimoya will defoliate and drop the apical buds after light frosts. If it's a particularly mild year without frosts (like our 2020-21 winter), the leaves will stay on until the tree starts budding out in April/May. The lower branches naturally form an espalier shape not unlike Coffea arabica. This tree receives no irrigation other than whatever winter rainfall we get and tolerates very high temperatures (no issues with heat waves in excess of 90 F in 2020).
December 2020 - the first fruit was an early windfall that cracked while it was still on the tree. They're small fruit but considering the trees are completely unirrigated I'm still impressed. Lots of seeds but the flavor is very good. Had to find a very small spoon to scoop out the flesh. You do not want to eat the skin or the seeds, everything on this plant besides the white flesh is poisonous!
January 2021 - the bulk of the cherimoya were ready in January. I'm not sure if there's a better way to figure it out, but I let the fruit pick themselves - if I fiddled around with the fruit for a bit and it fell off the tree, I'd take it inside to table ripen until the side yielded to gentle pressure (like an avocado), which generally took a few days. The largest of the bunch fit very nicely in my palms, and are maybe 3/4 the size of the small ones I bought at the grocery to start with.
April 2021 - like I said earlier, the winter of 2020-21 didn't have any significant frosts for us, so the tree was actually still covered in leaves in April when the branches are usually completely bare. The apical buds still have a tendency to fall off over winter, which seems to be part of the natural branching structure.
June 2021 - Despite keeping most of last year's leaves through April, the tree will still defoliate as the new shoots grow, so any leaf on the tree is no more than a year old.
So what's the deal with hand pollination? Well, despite having very fragrant flowers (they've got the same green apple/pear scent the fruit do), apparently cherimoya are only pollinated by either beetles or wasps that aren't found outside the plant's native South/Central America. There's a few practical issues with hand pollinating: (1) The flowers are incredibly inconspicuous. They're green and while pendulous, the huge leaves cover them so you can't see them even when standing right below a branch. Maybe you could find them by smell, but my sense of smell is very poor so I can't. The major leaf flushes also come at the same time as the flowers. (2) The flowers are protogynous, so an individual flower has 2 distinct phases where first the stigma is receptive, and only after do the anthers release pollen. With some experience, it's easy to tell the phases apart: the first day a flower is open, the three fleshy petals are barely open, spread mostly at the end. This is the female phase. The next day, the petals are widely spread, and in the evening when I do my pollinating, the anthers and pollen will fall when manipulated with a brush, which I collect in an envelope and apply to any flowers in female phase. The day after the male phase (the third day), the petals will be dry and brown, falling away from the ovary. If not successfully pollinated, the ovary and pedicle will fall on the fourth day. The good news is that cherimoya is self-compatible, so you don't need pollen from a separate tree. (3) The flowers are unpredictably placed. Flowers will grow on last year's wood, this year's wood, and even right off of the main trunk. Now that I need a ladder to work many of the flowers, this makes finding the flowers even more difficult.
I've got a few plans for my trees in the future. This winter I'll have to prune the tree a lot since even the 12 feet height it is now make it hard to work with. Apparently, down in Southern California they prune to get the trees to grow as densely as possible to increase the odds of spontaneous pollination. I'd also like to try eating atemoya - this sugar apple x cherimoya hybrid is variably rated, some say it's not as good as cherimoya, some say it's better. But the Geffner atemoya variety is supposed to set fruit well without hand pollination, so if it's tasty and I could find some scions it wouldn't be hard to graft them onto cherimoya branches.