What killed my greenhouse banana?

[drymifolia]

I planted a 1 gal pup of a Dwarf Cavendish banana in the ground in my greenhouse in spring 2021. It grew great that summer, then stopped growing over the winter, and started again the next spring. Last year it reached about 8' by the time it stopped growing in the fall, here's a photo from mid-October, it only unfurled one more leaf after the one unfurling here:



It looked fine for the first part of the winter, nice green leaves for the most part, with only the oldest leaves getting a little yellow from the cold temperatures. Here's a photo from mid-January:



Then, a little over a month ago, the leaves started dying at a rate of about one or two per week, from the bottom up. This was what it looked like by February 20, with most of the leaves dead but the inner leaves still mostly green:





Yesterday, I decided it was completely dead, it was almost a foot shorter than before (shriveled), the cigar was brown:



When I cut into the top, the heart was brown and soft:


As I cut off chunks to remove the rest of the p-stem, it started smelling a sickly sweet scent, similar to fermentation, and by the base it was very gooey and definitely starting to rot:


I had watered it pretty regularly, and tested with an orchard soil moisture probe so I only watered when it was medium-dry or drier. I don't think the problem was watering-related.

There had been a LOT of rain recently, and it's possible there's a deep perched water table that the roots didn't reach last year but they were waterlogged deep this year?

The weather was cold, but not colder than the previous year when it over-wintered fine.

My leading theory is some kind of soil pathogen that was able to attack easier in the winter when the defenses were down, but no clue what pathogen that might be.

Any thoughts?

[fruitnut1944]

Cold and wet is when pathogens attack. Banana isn't designed for even 4 months of cold, cloudy, and wet.

Do you know what your soil temperature is say 6 inches down? In my greenhouse it's now 65 early in the morning 6 inches deep.

[brian]

I also got a 1gal dwarf cavendish (last May) and it is in a greenhouse and about 8ft tall.  Mine is in a 25gal container.  Mine has been slowly putting out new leaves all winter and is still green, so it is definitely not just a northern greenhouse thing   I think waterlogged soil or cold soil could be a reasonable cause.  Have you checked soil temps in winter?

Or could be disease, I don't know much about bananas 

[Tropicaltoba]

So sad. I had a dwarf cavendish in a container that rotted as well just as it was flowering. I was able to successfully fruit a dwarf namwah with our any difficulty before the cavendish died. The only difference with the two was one was near a circulation fan in a warmer diet part of my greenhouse while the other was closer to a window.

[drymifolia]

I'm sure soil temperatures are lower than ideal, but I found it strange that it made it through last winter just fine with the same soil temperatures, and then was killed this winter. If I were to guess soil temperature I'd say around 50ｰF a little below the surface, just based on the average air temperature in there now.

Here is my greenhouse (air) temperature chart since Nov 1, the banana started looking sick around the end of January:



The banana was planted in the very center away from the walls, so the soil was as warm as possible in such a cool greenhouse.

The soil is pretty dry in there other than after I water. When I use the soil probe it's usually around 2 or 3 out of 10 around the roots a day or two after watering, and I wait until it drops that far before watering again. Humidity is pretty high at night, though, with condensation dripping from the ceiling.

I don't know of an easy way to check for a perched water table problem, if the soil is soggy 3+ feet down but dry as far as my 24" probe can reach. That's quite possible, but if so it hasn't negatively affected my avocados or citrus trees, planted next to it.

[elouicious]

watering regimen?

looks like rot to me

[Daintree]

I don't put anything in the ground because of poor drainage and cold soil temps.  Bananas love lots of water but hate cold, wet feet.
My bananas bloom and fruit consistently in 25 gallon pots. Much safer, easy to regulate the drainage and root temperature.

Carolyn

[drymifolia]

Since I only water when the calibrated 24" orchard soil moisture probe said it was dry, I'm guessing it wasn't my own watering that did it, and a perched water table rose up below its roots after an extra wet period in January and February.

There was no surface flooding, but the geological maps say there's a layer of impermeable clay below my subsoil, even though the subsoil itself has excellent drainage.

[Daintree]

Seriously, pot it up. You can totally control water, nutrition and heat. Your greenhouse gets colder then mine,  so you could even wrap heat tape around the pot.
I have mine down to a system -
1. In the early spring, separate out the pups and repot them. Keep the best one for a replacement and sell the others to unsuspecting homeowners.
2. Start feeding the hell out of the mother plant. It will usually bloom some time between May and September.
3. After harvest, throw away old plant, revitalize the soil and pot the best pup into the 25 gallon pot.
4. Repeat yearly until the grandkids are grown and I can't keep up with eating all the bananas (luckily my son gave me an AWESOME chocolate banana cake recipe that uses 12 bananas!)

I get bananas every year!

This year's plant (aka last year's pup)


Last year's crop

[drymifolia]

That's good advice for anyone else who finds this thread, but I'm planning to let my greenhouse get even colder next winter, since it's mostly for avocados that can handle the cold just fine, so I'm not going to try bananas again. I was planning to remove it after it fruited anyhow, since it was blocking the sun too much for other things in there, so it just removed itself ahead of schedule.

[Tropicaltoba]

What temp are u currently running it at? I知 contemplating dropping mine a bit (5c) so I can get more chill hours for nectarines but I知 worried it gonna mess up all my other stuff (I use organic fertilizers so nitrate production may get messed up). I currently have mine between 16-19c at the warmest areas, goes down to 8 deg on the coldest night by the windows.

[drymifolia]

What temp are u currently running it at? I知 contemplating dropping mine a bit (5c) so I can get more chill hours for nectarines but I知 worried it gonna mess up all my other stuff (I use organic fertilizers so nitrate production may get messed up). I currently have mine between 16-19c at the warmest areas, goes down to 8 deg on the coldest night by the windows.

My heater can maintain the greenhouse about 7-8ｰC above the outside temperature, but my sensor is near the center above head height, so it is likely much colder near the edges. It typically turns on just below 9ｰC, so that it runs in a saw pattern on nights where the outside temperature is just above freezing, and runs continuously on nights where it falls below zero C. Here's a chart for the second half of February, when we had some cold weather and the greenhouse got as low as 3.5ｰC, though the more typical range is from 6ｰ to 12ｰC at night in the winter.

[Tropicaltoba]

How do your citrus do at those temps? I知 worried there isn稚 enough microbial activity to keep up nitrate production when my soils are under 15c.

[drymifolia]

How do your citrus do at those temps? I知 worried there isn稚 enough microbial activity to keep up nitrate production when my soils are under 15c.

They all go dormant from fall until until around now, and some of them look a little pale by spring (especially the key limes), but no major problems I've noticed. My citrus are mostly pretty small still, though, so it's possible I'd notice issues as they get bigger.

I don't use any chemical fertilizers in case that makes a difference, but I use both liquid and dry organic fertilizer mixes.

I'm generally willing to sacrifice any citrus that can't survive, but so far that hasn't been necessary. I only have one large (5' tall and almost as wide) mandarin in the ground, the rest are smaller and in containers. My long-term goal will be just one mandarin in the ground (maybe multi-graft), one key lime, six multi-graft avocados, and if the one ataulfo mango seedling keeps surviving it can stay too. The rest of the space will end up being basically only potted avocados getting ready to be distributed to members of my cold-hardy avocado project, and a few trays of garden starts each spring.

[1rainman]

Id say it was stressed due to cold which in it's weakened state a fungus like anthracnose got it even though normally it would be immune. I have seen bananas thrive in drainage ditches. Wet soil usually isn't a problem.

I suggest getting the most cold tolerant banana varieties you can find they will be a lot less stressed. My favorite variety raja puri has good tolerance and there's some with even better tolerance.

My bananas would grow better in the summer up north than in Florida. They just went crazy outside. Indoors during winter they never did well for me spider mites not enough light. But they never rotted or died.

They naturally die at the end of their life cycle usually after having bananas then new pups pop up from the corm. So the older one is probably more seceptible to death than a younger one.

Maybe try Orinoco or raja puri

[1rainman]

Also bananas will grow in pure mulch. You can pile up a big pile of mulch and compost above ground instead of a pot which will warm itself as it roots. Bananas just got too root bound even in giant pots. You can't over fertilize them either so a giant pile of compost or mulch is not a problem they do better in it and high acidity doesn't bother them.

Even though 50 degrees is not a problem for a banana they love heat. Long periods without hot weather will stress them. So go for the most cold hardy types and give them a big mound of compost and mulch which would keep them out of deep water. They don't grow deep roots. They just make a giant bulb-corm underneath which they store energy and sprout pups. Their roots would mainly be in the warm mulch pile which will shrink as they eat it and need replenished.

It could have reached the end stage of life and said I'm too stressed to make bananas. They are messy plants with lots of dead leaves and when it does normally is wet rotten like that but new banas grow out of the rotting ones.

[1rainman]

Also bananas need to drink from their leaves and stems. So high humidity is desirable. Or when you water them spray the leaves. This could be stressing them too. Low humidity in winter no morning dew or rain on the leaves. That's one problem I had in winter which also led to spider mites from leaves not being sprayed enough. But I mist them or run a humidifier at least a little.