AusBonsai

G'day all,

I have a bunch of small elms going through their first summer with me in Ipswich QLD. They are all mostly in 10cm pots and were grown from root layering. I have a couple of corky barks as well.

The problem is that all my leaves have dropped of over the last couple of weeks. They go brown and drop, although they are still showing some new branches sprouting.

There are no pests that i can discern. I haven't really fertilized much either. I water every day and have noticed that the soil is still quite damp in the bottom of the pots, even after a day of mid 30s heat. I doubt the pots have ever dried out much.

I can't think that I'm not watering enough, nor a deficiency in nutrients.

Could anyone advise how i could trouble shoot this problem? They have all been going well apart from the last couple of weeks.

Thanks,
Steve

First though this time of year is they got dry, especially in such small pots but as you are confident they have not ever been dry it may be something else.
Photos are always a great idea as someone may be able to spot something you have not even considered but no chance of that with just your description.
Too wet is a possibility. If the pots are always wet you can get root rot and results are similar to dry.
Another possibility is they've got root bound which can mean that no water can get into the centre of the root zone and that means they can be dry even when there appears to be some dampness around the outside. Usually takes a couple of years to get that bad though.

Without more info I can't think what else could be doing this.

Photos. Yep. Good point.
The pots are kept mostly in shade with direct early 30s morning sun. They were all potted up last spring.
Substrate is largely organic with some sand and a bit of perlite as well. It’s a bit of a mystery, especially since other plants are doing well. Anyway, if anyone has any thoughts that would be grand.

Looking at it, it looks like it’s too wet. Also looks to have scale and some other insect activity under the leaves. Hard to tell from the photos exactly what they are. Have you tried to gently tap it out of the pot to inspect the roots? I think you may find below the surface it’s very wet. Still I’d keep it away from your other trees.
Cheers
Kirky

Yeah mate I think you’re right on both counts. I’ve had a lot of problems with ants and other beasties.
Is the best treatment to simply let the pots dry? Is there anything that can be added to the pot? Or should I repot the plant with better draining soil?

Thanks

Ants usually indicate scale as they love the sweet excretions the scale produces. Chinese Elms are pretty resilient. I would tap it out and check the state of the roots if really wet and if the roots look unhealthy or smelly definitely repot.
Other wise if your not game move it to a similar position the healthy tree is in, but not too near the healthy tree you don’t want it to contaminate the healthy tree.
Also spray the sick tree with something like Yates Scale Gun, make sure to spray the entire tree including under the leaves. I also spray the top of the soil. Spray as often as recommended on the bottle of whatever product you end up using.
Cheers
Kirky

That’s great Kirky thanks. I actually thought the ants transported the scale up the stem, but I get it now. I wonder if the presence of ants indicates scale as well?
I’ll take the plants out and have a look. It’d be good to learn what the roots look like if there is rot.
Thanks again

Steve

I would consider:
- fertiliser burn
- drying out & or staying too wet

I pulled out my plants last night for a look.
The one in the shallow pot was root bound with a decent root ball, which explains that I hope.
The other two were pretty much water logged. What I realize now is that because of their age there isn’t much root system to speak of on the last two, which meant that the water wasn’t being taken up as quickly.
Hopefully they will recover, but either way some good lessons learnt here.
Thanks

Plants with smaller root systems will need a small pot and less water. Both combined improve the root growth. As the plant grows and develops an upper story. Then watering can be increased.
Basically:- no to little leaves less water. Larger pots with little roots stay wetter longer because their is not enough roots to draw on the water. End result can be poor growth and or root rot.
Put the smaller ones in the sun and carefully monitor wetness the old finger or chopstick to see how wet pots are before watering.
Cheers
Kirky