Chud

Good morning

My (from seed) M. Sikkimensis have taken a relatively sudden turn for the worse. They were looking a bit pale so I moved them into my conservatory prior to them being planted out later this month, I was just waiting for the current spell of wet/windy weather to pass before planting them in the garden (after hardening off).

About a week ago I gave them a feed of all-purpose liquid feed Gro-Sure All-Purpose Plant Food | Plant Food | Westland Garden Health | Westland Garden Health and they seemed to be 'waking up' a bit - pushing out new growth but yesterday I realised they were looking unhappy with white stuff on the leaves and yellowing and blackening occuring (see images).

Is this mould from being inside/restricted airflow etc a bug, disease or something else??

Your help greatly appreciated!

https://goo.gl/photos/DgQEHBNa2H53CQ1T8

https://goo.gl/photos/2L5Edi9KJS2uukwk8

https://goo.gl/photos/2y9p48RCVs1upPhDA

https://goo.gl/photos/KJPUeg5ysRbviRe4A

beam2050

do you have a picture of the p-stem/ did you ad a fertilizer? what and when?

__________________
...................................................

npk of wood ash 0/1/3 to 0/3/7

npk of banana leaf ash 1.75/0.75/0.5

edwmax

Was anything spilled or sprayed on the leaves to cause the white buildup?

What is the Ph of the soil?

__________________

Chud

Peristem photo - Can grab one tonight but it doesn't look abnormal to me (still surrounded by dead 'leaf husk' etc though.

I gave them one feed of the Gro-Sure feed I linked to (at a bit below the stated dose, it's NPK 5 – 3 – 8) as despite good doses of sunlight in the conservatory they were looking a bit pale.

The conservatory temps have fluctuated quite a bit in the last few weeks between ~9C at night to ~30+C on some days (if it is all shut closed because we are out etc.) but I didn't think too much of that as that is the temp range recommended for seed germination for Sikkimensis.

Chud

No - nothing has been sprayed on the leaves although I do see a fair bit of guttation when they've been watered? Not sure of the pH but they're in a coir, vermiculite mix so probably neutral.

Chud

More info on the feed I used:

Nitrogen (N) total 5.0%
Ureic nitrogen (N) 4.3%
Phosphorous pentoxide 3.0% (1.3%P)
(P2O5) soluble in water
Potassium oxide (K2O) 8.0% (6.6%K)
soluble in water
Nutrients with levels below the minimum
declarable content as stated by the Fertiliser
Regulations are as follows:
Magnesium Oxide 0.04% (0.02%Mg)
(MgO) soluble in water
Iron (Fe) soluble in water 0.03%

Also we've had a wet and windy spell here since the weekend so humidity has jumped right up and it's still fairly warm.

Gabe15

It seems to me there are a couple things going on, none of which appear detrimental. There doesn't appear to be any disease or pest issue present. I would guess it's a combination of too much fertilizer, and wide temperature fluctuations.

The white deposits on the leaves could be mineral residue leftover from guttation, exacerbated by the dose of fertilizer given earlier. Small plants in small containers growing only leaves require just a minuscule amount of fertilizer to stay healthy, and adding too much fertilizer can easily build up in the soil and start to cause growth issues as too much of some minerals can block the uptake of others, it can affect pH which changes the plants ability to uptake all nutrients, and it makes water harder to uptake in times of need (especially when it heats up). Add to that low temperatures which slow growth, and the fertilizer demand is reduced even further. When I've had to maintain small potted bananas in a greenhouse under fully tropical conditions and active growth, I've found that a tablespoon of slow release fertilizer applied every 6 months is adequate, and even then I would periodically drench the plants until water ran from the pots to aid in cleaning out any excess fertilizer buildup. Even when you do all this you can still get excess mineral buildup if you have hard irrigation water, so going light on the fertilizer is normally a good idea until they get into the ground, and then you can step it up. Notice the newest leaf on your plant is smaller than the previous leaves, that is a classic sign of too much fertilizer for a potted banana.

The temperature fluctuations, though tolerable (it's not dead), do put stress on the plant, and that could explain the yellow and black coloring alone, but could also be exacerbated by the excess fertilizer. Additionally, temperature fluctuations are more drastic for small potted plants as the entire soil substrate and root system heat up and cool down rapidly, which would normally be slow to change if it were in the ground even if air temperatures are swinging up and down.

As for what you should do, I would run water through the pot to try and wash out excess mineral buildup, and just hang tight until you're ready to plant it out, hopefully not more than a few weeks from now. When you plant it, mix a decent amount (up to 50% is fine) of some high quality compost into the planting hole to add organic matter which will help to buffer against any remaining excess fertilizer, and provide nutrients to the plant as it starts growing without you having to worry about fertilizer for awhile, potentially all season. Mulch it well, and if after a few months it's still looking bad, then it might be time to start worrying again, but I don't think you'll have any major issues provided it has good sun and kept well watered.

__________________
Growing bananas in Colorado, Washington, Hawaii since 2004. Commercial banana farmer, 200+ varieties.

edwmax

Dang! Gabe .... That's always a mouthful to explain. You cover it all. ... Only I would also suggest daily misting of the plant with water to keep it hydrated until the roots come back to full function.

__________________