The Tropical Fruit Forum

So... I'm baffled. While caring for my plants, I found this fruit on the ground. It had been stepped on and was highly mangled, so I don't know what it originally was.  But some key characteristics can be seen - the four-pointed puckered shape at the bottom, red skin, soft / juicy orange flesh, and a single large round seed. There was enough of the flesh left unmangled for me to try it - it tasted very much like plum.




My first thought was strawberry guava. It was right next to a plant that (at least according to my records, and certainly by appearance) is strawberry guava, and it's been blooming a lot recently for the first time. I hadn't seen any fruit on it, but another one of my strawberry guavas has its first immature green fruit on it (tiny little plant, I'm amazed that it can hold fruit!).  But beyond the flesh being wrong, strawberry guava has small seeds, not a single large one.

The single large seed makes me think eugenia. Indeed, there was also a rainforest plum right next to it. But it's another tiny, tiny little juvenile plant, maybe 15cm tall, and I hadn't seen it bloom. Certainly doesn't look like a ripe rainforest plum.  But maybe half ripe?

My acerola is fruiting, and it overhangs a bunch of other plants, and the fruit could roll.  But that certainly doesn't look like acerola, esp. since acerola has three irregular seeds per fruit.

There's so many other plants on overhanging shelves or overhanging or growing around generally around the room, but apart from some capsicums, none have visibly flowered or fruited, and most are varieties that one can rule right out, like cocona, garcinias, jackfruit, lychee, passiflora, palms, mangoes, coffee, tamarind, physalis, mamey, annonas, citrus, and on and on and on (it'd take some time to compile an exhaustive list). 

(There's no possibility that this was some sort of supermarket fruit, as I haven't been to the supermarket since March    ).

Thoughts?

... you may find this paper about soil heating to be of interest 

https://www.keilir.net/static/files/KIT/PDF/1power2013-98172.pdf

In Iceland... where *July high temperatures* are usually only about 15°C / 59°F on average - with soil heating they were growing and fruiting tomatoes and zucchini outdoors.  They grew a banana plant to and past the first frost (though obviously did not attempt to overwinter it). They basically got the same sort of results you get with polytunnels, simply by heating the soil.

Definitely worth some followup research......

So, there's only a couple non-fruiting plants among my tropicals, and one of them is a drosera (sundew), which helps ensure that flying pests don't get out of control. The other evening I was doing my periodic pH measurements and I got to the drosera (a relatively recent acquisition, never-before measured), and the results were so off the chart that I actually went back and recalibrated my pH meter. Its soil was pH=3,1!  Lowest measurement I've ever seen - that's like soda.  Droseras certainly tolerate acidic soils, but they generally prefer at least pH=5,5 from what I've read, and too low pH hinders their growth rate.

I was going to just lime it, but then I ran into another tidbit: apparently most droseras are calcifuges. They hate calcium.  And they generally prefer nutrient-poor soils in general. Well, that leaves me in a conundrum: how do you raise the soil pH if the plant hates calcium, and most nutrients in general?  Is my best bet just transplanting into new medium?  Or should I just let it be, since it's seemingly healthy?

I should soon be getting an order of seeds, among them Pentagonia grandifolia. The last time I ordered them, I was thrilled to get nearly 100% germination (which, given the small seeds, was a lot of plants!). But that was then - slowly, one by one - followed by 100% damping off  :Þ

Any tips for preventing damping off in sensitive species?  I'm thinking about:

1) Going with a 100% inorganic starting medium, and only moving them to soil when they outgrow it. Frequently moistened sand / perlite, so it drains well?
2) Dissolving captan in the water that I water with (my captan supply is old... will it still be functional?)
3) Keeping at least some of them in a humidity bag well past the germination stage (in case insufficient humidity was the cause, rather than fungus).  My plants grow in an area that's high humidity, but not "near 100%"

Do these sound like good ideas?  Any other suggestions?

Ran into a very interesting paper researching coffee productivity (was actually searching for artocarpus response to light at the time, but I'll take it!)

http://corridor.bangor.ac.uk/documents/treesoncoffeeplantationsreport.pdf

Key takeaways:

 * Photosynthesis rates of sun-adapted leaves are about 80% at 500 umol/m²/s, 90% at 750 umol/m²/s, and 100% at 1300 umol/m²/s. Full sun is around 2200 umol/m²/s; the extra sunlight only serves to inhibit photosynthesis
 * This is amplified by means of the fact that coffee leaves live longer in shade, and thus less energy needs to go into their production
 * Opposing this, however, is real-world data showing that coffee production is higher in the sun than the shade - multi-year yields are just under 80% of max in full sun, 100% in 75% sun, a bit over 80% in 50% sun, and around 30% of max in 25% sunlight.  "Good year" yields are even better for full sun - nearly as good in 100% sun as 75% sun, and nearly 4 times more in full sun than 25% sun.
 * The reason for this is that the internode length increases in the shade, and thus fewer flowers are produced (note: not discussed in the paper, but if one wants to counter this, blue light is known to reduce internode distances).
 * Somewhat (but not significantly) offsetting this is lower fruit drop in shade coffee.
 * Because energy is abundant in shade coffee, but full sun coffee produces more fruit, shade coffee yields a higher-quality fruit, while sun coffee stresses itself out to the point of resulting in a partial alternate-bearing habit.
 

https://fshs.org/proceedings-o/2001-vol-114/177-181%20(JIFON).pdf

Maximum net CO2 assimilation of most citrus cultivars saturates at relatively low irradiance (600 to 700 umol m-2s-1), which is only 30 to 35% of full sunlight (1500-2200 umol m-2s-1) on a typical growing season day (Syvertsen, 1984). The excess radiant energy predisposes plants to photo-inhibition, heat stress and stomatal closure, resulting in a reduction in net photosynthesis (Pn), the ultimate source of fruit soluble solids.

Experimenting with grapefruit, they found no meaningful change in yield for using 50% shade cloth from Apr-Jul, but a 35% yield improvement for using 50% shade cloth from Jul-harvest.  A caveat that they encountered was that while reducing light levels was good on sunny days, on dimmer days it reduced the light levels down to below the plants' limits, and thus reduced photosynthesis. So "adaptive" shade might have been even better.

What's your experience with shading?  I had always thought that, with a few notable exceptions (such as finger limes), citrus trees were full sun plants that were significantly adversely impacted by shade.  But this argues otherwise.  Could citrus be effectively intercropped?

So, I was looking at my compost pile today, and - noticing some langsat rinds on the top - I recalled reading about how dried langsat rind can be used as incense.  So I decided to try it out.

One quick recommendation - don't leave them in huge chunks that pack poorly together, cut them up to the degree necessary so that they pack in reasonably well together.

One thing I was really impressed with was how it burns.  There's apparently a flammable oil in the rind - you can see it bubble out - and it maintains this perfect nice, slow, steady smouldering - just what you want in an incense.  Nice pretty wispy waves of smoke come off of it.  Unfortunately, the scent on its own wasn't remarkable - there was maybe a hint of langsat scent in there, but it was mainly just a smoke scent.

I'll have to try this again, but this time dripping some essential oils onto the rind to give a more interesting aroma. But as far as reusing waste goes, this one really seems to work.

ED: Found a bit more usable rind and tried it with some essential oils.  The oils turned out to act like an accelerant - which in a way is good to an extent, as it helps all of the pieces catch fire, but it also burns them up faster - and you don't really want to be burning *off* your essential oils either.  I almost wonder if the best option might be something like langsat + a little essential oil "ignition" fluid + dried citrus peel, to get some sustained essential oil release in there.

One thing that's kind of neat is that for a while you can get this "floating fire" effect, where it looks like the air over the langsat is burning, not the langsat itself:



If you like incense, it's worth giving it a shot 

I'm curious, who here (who sells live plants) is under phytosanitary control and certified for their export?  I know a number of people here as seed sellers (and have purchased from some before), but have not previously had need to purchase live plants so have not looked into it.  I'd much rather to purchase from people here than from elsewhere 

In general, we can import pretty much anything tropical.  E.g. nobody's worried about the "Icelandic citrus industry" being hurt by citrus psyllid or about strawberry guava becoming invasive or whatnot 

So, I made a thing 

https://docs.google.com/spreadsheets/d/1P-AoOGdl2ZHcm1Es0p5VLGsLWp3ffKbpYQuhpkcXCSg/edit?usp=sharing

Still very much a work in progress, but I thought I'd share: as a tiny portion of the database project I've been working on, I wrote a program that parses plant habitat descriptions and combines that with climate data to determine what sort of native environments they're grown in (this is combined with some curated data concerning what conditions the plants are known to like growing in.).    It looks at the plant's native altitude range and only includes points within the habitat areas which are within that altitude range.   If it can't find any locations that match the stated altitude in the stated range (e.g. the resolution is too coarse), it uses what data it did find and adjusts temperature, etc for the altitude difference. 

Now, some caveats.

1) It's a computer without a brain having to read text.  Subtlety will pass it by.  I've tried to include common edge cases - for example, "Located in X, not found in Y" - it'll see Y but not parse it.  It also tries to, when it sees "Found in X (Y)", where either X or Y is a subregion of the other, only parsing the subregion, not the whole.  But expect some mistakes.

2)  A lot of the mistakes are in the habitat description itself. For example: Artocarpus lakucha comes up with an average wintertime low in its range of 6,1°C.  Now, we know that it's not native to such cold climates. How did it come up with that?   Well, the range description is "E. Asia - Malaysia, Sumatra, China, India, Nepal, Sikkim, Myanmar, Laos, Vietnam, Indonesia, Philippines".  So it's looking at the climate of all of those - including all of China.  We know in reality that you'd only find it in the warmer parts of China, but that's not what the description says.  So, vaguery = bad 

Feel free to improve habitat descriptions to be more accurate!  You can use countries, subregions, cities, etc.  Just try to make sure that you don't name a place that has a more major (population, significance, etc) area with the same name!  It understands adjectives such as cardinal directions (including e.x. "northeast", but not "northnortheast") as well as "central".  Scattered city listings are just fine.  Let me know when you make any changes of significance and I can re-run it.

3) It does not understand the common wording "through" - e.g. "Portugal through Greece".  It will only look at the endpoints.  Again, feel free to improve this by being more specific.

4) The data behind it is the same data behind this site:

http://climatemaps.romgens.com/

But some of that data doesn't match other sites.  For example, they show a much dimmer winter in Manaus than you get when you punch Manaus into PVWatts.  I'm still trying to reconcile that.  Another example is in humidity; the average humidity figures seem to match the figures you'll see reported for average humidities for cities on Wikipedia, but when you go to daily weather histories on Weather Underground, it feels a bit off, particularly on daytime humidity.  Again, not sure how to reconcile that; this is just coming from the data I'm given.

5) There's still a good number of duplicate / synonym species that I need to work out, and a LOT more curating that needs to be done.  A known bug is that sometimes it'll list "kill temperatures" as "minimum acceptable temperatures", although it's generally very obvious when it does that.

6) It ignores everything up to the first dash (if an "early first dash" is present), to avoid parsing e.g. whole continents.

All that said... enjoy    Don't be too hard on me about errors, this is a first draft (there might even be some alignment errors pasting into Google Docs!  I haven't had much time to go over it). Just point them out, and where you can and/or improve the data (anything at where it says "Known preferred climate" or to the right) and let me know what you changed (otherwise it might accidentally get wiped out when I do future runs!)  I see one issue I'm going to check into this evening, where an acacia is getting a lower temperature rating than I'd expect.  I want to make sure that at least the algorithm is doing everything right, even if some of the habitats are poorly described 

(I have a LOT more data I'm collecting, but I'm still going through it)

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...

Much appreciated by natives in central Australia, particularly the Aranda people. Woody fruits up to 9cm in diameter; flesh inside is sweet, oily and milky, with a taste reminiscent of coconut, and very nutritious.



C. pomiformis seeds are tiny, round, soft, and have a short lifespan.

Shade tolerant. Dioecious. Fertilized by insects. Cannot be grafted or air layered, but comes true from seed.

Available for only a short period of time; get 'em before they fly out the door!

As discussed here, somewhat offtopic:

http://tropicalfruitforum.com/index.php?topic=27233.0

... I've long been rather lax about my fertilizer routine, and am working to amend my wicked ways    In regards to this, I'm working to treat a deficiency in my Fiji Dwarf coconut.  Symptoms:

 * Deficiency in a mobile nutrient (N P K Mg Cl Mo Ni), as the symptoms are in the oldest leaves, while new leaves are just fine
 * The main symptom is chlorosis, eventually progressing to necrosis.  Chlorisis begins further down the leaflets, yellowing (pure yellow, not spotty/blotchy), affecting the central vein and the edges last.
 * This, I understand, to be a symptom of K deficiency, which I also understand to be the most common deficiency in palms

Leaf that is mostly yellowed, but necrosis is just beginning at the tip:


Zoomed in to the necrotic portions:


Leaf with nearly-full necrosis next to it:


Section of a leaf going chlorotic:


Comparison between the basal portions of the necrotic vs. the yellow leaf:


Older images of an old frond (ignore the cutoff leaflets on the right):



Progression of yellowing up the same old frond, 2 1/2 weeks later (sorry for the red lighting):



Attempts at treatment thusfar:

 * Started out rather half-arsed 
 * First looked up *proper* fertilization for coconut palms, which for a palm the size of mine should be about 200 grams of my fertilizer I had been using** per month, plus extra potassium. I had probably been averaging about 50 grams, with no extra potassium - but it's hard to say because I hadn't been measuring.  The fertilizer is 12-14-14.
 * I started out just giving a proper single monthly dose at the start of the month, but that did nothing to reverse what's clearly been a problem that's built up over time.
 * Over time I made minor, trivial additions of more potassium, magnesium, and trace elements, as well as starting foliar feeding (but AFAIK that was kind of hopeless for macronutrients like potassium)
 * Eventually (~5 days ago?) I looked up how to treat a potassium deficiency, and found out that the amount of fertilizer I should be adding to remedy is huge, something like 1 to 1,5kg, and that it should be a 3:1 ratio of potassium sulfate to magnesium sulfate to avoid inducing magnesium deficiency.  I've so far added about 400g, as I don't want to add it all at once (it's been in two doses so far)
 * Today - although it's doubtful that it's the primary problem - I also added some (maybe ~80g) of sodium chloride (just regular table salt).  Our water isn't chlorinated, so this tree has probably never gotten any added chlorine in its life, and my reading was suggesting that coconut palms are unusual in actually liking chlorine, and that addition of saltwater has been known to help perk them up.  Adding salt to soil goes against every bone in my body, but....

The palm is 3,2m (10' 6") tall to the top of the highest fronds, with the fronds starting to separate at around 80cm up (2' 6"), and a trunk diameter of 10cm (4").  The soil depth is 60cm, and the pot is 80cm wide.  So in gallons, that's probably around 50 gal.  5 fronds - 2 old fronds undergoing chlorosis / necrosis to varying degrees, 2 mature and mostly or completely healthy fronds, and 1 new frond opening up.

The other issue that comes to mind is root health.  Shot suggested soil temperature, pathogens.

Soil temperature should be around 24°C (75°F), day and night, all seasons, at all depths.  Air temperatures vary, and increase with height, but probably average around 30°C (86°F), and humid.  I didn't used to, but I've taken to misting my plants several times a day as well.

I did have an outbreak of fungus gnats starting last month and peaking several weeks ago.  Their numbers have been declining of late as I found a place where I could buy predatory insects (yeay!).  They're still around, but not nearly as common.  Apart from fungus gnats, the only other pest that I ever have had problems with is spider mites (they've killed more plants than I care to admit over the years).  No unusual numbers of them of late, and I bought some predators for them as well just in case.

Aeration: the pots have holes drilled at the bottom, but they're such large pots, and plastic, and the soil is so moist, that obviously root rot is something to consider.  Normally I try to prevent this simply by not watering the large pots too often, but now I'm facing conflicting interests; I have to water to rinse fertilizers into the soil (and the more I water, the deeper they'll wash in)... yet if root rot is of concern then I want to water as *little* as possible.  I have no frond wilting, so that's a good start.  I did - 2-3 weeks ago - drill a lot of side holes.  I might go in at some point and double the number of side holes.  I obviously don't want to go so far that I ruin the pot's structural integrity, or I'll have to coat it in fibreglass to reinforce it - but I could probably do more.  Regardless, the soil is very moist right now.  Question of whether I should be relocating the palm to outside the humidity tent to try to dry it out, or just backing off on waterings (aka, washing in nutrients) for a while.  Again, there's no wilting, so maybe it's not a primary concern right now.

Thoughts, suggestions?

I'm finding some rather limited - and perhaps incongruous - data on the yields of jaboticaba species and their relatives (optimum soil / sunlight / feeding conditions), and I'm looking for feedback 

So far I've only found two references that seem of utility: one said that Myrciaria dubia / Camu Camu yields 12t/ha in cultivation (rather low by fruit standards, about 40% more than Mangosteen - a standard low-yielding fruit).  The other states that a mature Jaboticaba (apparently Sabara) yields 1000 pounds (~400kg) in Brazil.  Going with the assumption that by mature they mean "huge", and going with 9 meter (30 foot) trees, spaced 9x9 meters apart (from the same source: "He felt that 30 feet was the correct spacing without pruning"), this works out to around 50t/ha, which is a very large yield (say, high density oranges grown under optimal conditions, or double that of high density mango cultivation).

For you growing jaboticabas, what would you estimate yields would be for your various species/varieties, and what said "optimum conditions" would be?  I assume that you don't know t/ha figures, but I can work with any sort of figures - e.g. "The yield is similar to oranges", "I get about X pounds per fruiting and Y fruitings per year on a tree that's Z feet tall", etc.     Even comparisons of annual yields between different jaboticaba varieties would be of use! 

(Note: per year, not per harvest    )