Cotoneaster problems

Hey guys,
Any ideas on what might be causing this?
I’ve first seen it last spring when it started to push.
First I thought it was late frosts or wind damage but it kept on going throughout the growing season, causing dieback.
This year it came back and I was extra careful this time with weather exposure.

Any thoughts?



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I have the same problem showing on several of my plants: trident maple, magnolia, Stewartia and linden. I thought it was a fungal problem but I haven’t seen any photos of this problem anywhere. Also none of the typical fungal treatments seemed to make any difference. Now I’m thinking it may be a result of overwatering. I’m being super careful with my watering now and using a moisture meter. It’s too soon to tell if the problem is improving but I’m hoping for the best.

Not sure if it was overwaterig but it was definitely root related.
One seemed to pull through the other one I lost.

Did you perform an autopsy of the roots of the dead one? I try to do that whenever one of my trees die. I’m still evaluating my trees but I’m watering carefully now and using my moisture meter. I recommend getting one if you don’t already have one. Fairly cheap, not too expensive. I’m amazed that I’m finding high moisture content in pots that I’ve been watering every day. Now I’m going 2-4 days between watering of some plants. It will probably take a month or two to see if its making a difference.

I did pull the rootball apart, nothing specific there.
best guess is that some late frosts stated the downward spiral and by the time I noticed it was too late. Sadly it happens from time to time.

Unfortunately failure has been one of my better bonsai teachers. I live in Northern California and we also experienced a late freeze which was devastating to many plants. I’ll continue to monitor this browning of the leaf tips problem and pursue the theory of overwatering. Good luck with our future bonsai endeavors.

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Hi Kenez, Do you over winter your cotoneaster in a greenhouse? I leave mine outdoors in all weathers but I don’t know how cold your area gets. When you pulled the roots apart on the dead one did you see any small nodules or had clumps of roots become detached from the trunk ? Do you have vine weevils or other root eating grubs where you are?

Hey Keith,

Wintes are not as cold as it used to be but we still dip down to -25 ish C from time to time so I have to keep everything in an unheated balcony roughly around freezing point.
As for the roots I didn’t see anything, no nodes, bugs or fungus.
The one thing I’m sure of that I messed up is that I defoliated it last fall when it went dormant- that was a bad call. One thing when they do it naturally do to frosts but it seems that was a bad call on my end that may have pushed it closer to the brink.
Cheers!

Hi Kenez, here’s a few things you could try; using only rainwater for a while, watering less frequently (cotoneasters are reasonably drought tolerant), remove the fertiliser and clean off moss from the surface to allow the roots to ‘breathe’.

I just started adding a bit of fertilizer since all new growth is healthy and pushing hard. Seems to be recovering nicely.
As for watering, I use RO water 'cause the one I get from the tap is rock hard with a pH of 12-ish.
My plants seem much happier since I use this.

Ouch!! I thought I had problems with hard water. It’s a case of wait and see now… I’ll keep my fingers crossed