S.O.S. (Save Our Seiju)

[BirchMan]

Hi all
I recently had a pic of this one up in the Air Layering thread but it's declined a bit in the last couple of weeks. I suspect the roots got too hot as I noticed (too late) a couple of hours of intense afternoon sun striking the pot directly before covering it with shadecloth. Otherwise the plant is under 50% shadecloth for about 5 hours' filtered sun every day.
About 8 weeks ago I noticed patches of foliage had browned off and I suspected a thrip attack. I had also noticed webby structures where browned leaves were gathered together. I hit it with a dose or two of Mavrik sucking insect killer and continued my water regime of flooding every 4 or 5 days (as I gauged from the top few inches of soil). It bounced back pretty well, but after my air layer maintenance post where I didn't touch the rest of the tree, the browning returned in force, this time the browned leaves were soft and droopy. Clearly the roots aren't getting enough water to the leaves. About a week ago I dug a bit deeper in the soil and it looks like the hot sun on the side of the pot, plus the natural demands of the tree I suppose, had the soil surprisingly dusty dry. I flooded it properly and it has since remained quite damp, and is trying to push new growth from branches and low on the trunk. I pulled it out last night and the roots don't look too potbound, nor are there clear signs of damage.
Of course I've removed the air layer, and will slip it back into the pot for the day. It is in a loamy mix and was previously in a self-watering pot.

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Any advice to stop the rot would be appreciated!
BM

[KIRKY]

Not sure where your air layer is or if this is the air layer. To me looks like the tree was slip potted into a pot and topped with Sandy loam on the top half of the pot. Bottom of the pot where the roots are look compacted and probable not drawing enough water. That would be why it recovers after a good soak and then starts to wilt as it dries out.
I would put a water tray under it and see how it goes. The web may be spider mite but hard to tell in the photo doubt that would be causing the wilting. Also on one of the pic’s there is a brown spot is that scale? Again hard to tell.
But I still think you have a watering problem try the tray and let us know how you go.
Cheers
Kirky.

[Akhi]

Second the view about lack of water reaching the roots. I had a similar issue with an azalea which sadly died early in my bonsai journey. Found out later as much as I was watering from the top the soil had become hydrophobic and was not letting it get through to where the roots are. For a start as you are in autumn should get through.
Suggest you dunk the whole pot in a bucket of water and leave it there overnight.
Take the pot out stick an upturned 2 litre coke bottle into the soil and use it to water the tree so the water slowly percolates.
Good luck.

[BirchMan]

Thanks Kirky. Nope that's the parent tree, about 2m tall with multiple trunks - hopefully the source of many future air layers. I've only owned it about 9 months and haven't repotted it yet. Was hoping to get it in the ground later this winter.

[BirchMan]

Adding details as they come to mind. When I watered it thoroughly with a flooding, a lot of air bubbles came up indicating there were dry pockets deep in the rootball. I will make sure it's soaked, maybe with some diluted seasol ASAP.

[KIRKY]

Sounds a good idea. Seasol have a hydrating soil wetter if your pots tend to be too dry. Otherwise just sit in a tray of water for upto a week then water normally soil should after sitting in water tray for a week start to absorb water.
Cheers
Kirky

[shibui]

Almost certainly a case of not watering adequately. Every 4-5 days through summer seems to be very little for a tree of that size in that pot, even given we have had a relatively cool summer this year. I would certainly be watering every day or 2 here.

As mentioned above when soil gets dry it becomes very difficult to rewet so even though you think you are pouring on lots of water and some runs out the bottom of the pot the soil is not actually filling with water. Each day the root ball get a little bit drier until the tree collapses.
As also mentioned immediate first aid is to soak the pot in a tub of water overnight to make sure the soil is properly wet again. Follow up with better watering practice to make sure the soil gets wet when you water.

I really doubt that sun on the pot is to blame. I know I read lots of talk that black plastic pots heat up in sun and cook the roots but I have not seen that happen. If it were a problem surely the nursery industry would have moved away from black plastic by now?
Sun on the pot may add a little to evaporation but far more water seems to be taken up by the tree. Make allowance by watering a little more often.

I also doubt this is a case of root rot. Any dead roots here are more likely to have died from lack of water. With proper watering they should begin to grow again.

[BirchMan]

Thank you, shibui. My mum tells me I water too often, but she doesn't do bonsai! I guess after 10 or more years I'm still learning watering practice.

[KIRKY]

If it’s in a bonsai pot at this time of year daily, even twice a day. In black plastic pots every to every other day.
Remember bonsai only rely on you for everything, water, food, fresh repotting soil. They can’t go looking for water like trees in the ground.
Cheers
Kirky

[TimS]

Yeah that seems like severe undewatering to me. There isn't a time of year where i would go 4 or 5 days without watering anything including the stuff still in nursery pots, let alone in summer

[BirchMan]

Let's hope this lesson doesn't come at the cost of this stock tree. It'll be thriving in the ground this time next year