Advice on Acer palmatum leaf problems please :-)

Dear Gardeners,

I've been asked by a friend to remedy the problems with this Japanese Maple, possibly Acer palmatum 'Garnet'.

In the first photo you can see it as it was when I first saw it. It has been planted in a largish plastic container. Apart from the highly curled leaves, the first thing that struck me was the large number of nettles growing in the container around it. I know Nettles are an indicator of high soil fertility......but possibly the growing medium was contaminated at the point of planting. I then removed the nettles and began to inspect the growing medium. It appears NOT to be a soil-based compost (eg 'Added John Innes') and is probably just a compost sourced from a Garden Centre......though that does seem to be at odds with the Nettle colony!
My understanding is that Acers in containers need a soil-based, ericaceous growing medium so that may be a big part of this plant's problem.

I then began to scrape away the growing medium to get to the roots. About an inch below the surface I reached a layer of chippings (Coir?) which are presumably a legacy from when it was propagated at the Nursery. It therefore looks like whoever planted this Acer out set the first flare or roots deeper than the compost in the container. The bottom inch of the stem is visibly discoloured, presumably moist. Again, not good but no signs of Stem Rot yet.

I know that exposure to drying winds and under-watering cause Acer leaves to go brown and crispy and can cause leaf curl. This particular plant is sheltered from the worst of the afternoon sun by a nearby Tamarisk and is likewise sheltered from strong winds by an adjacent medium-height fence. The presence of Nettles suggests that lack of moisture has a not been an issue.

Clearly there are problems with the root environment with this plant, but would they alone cause this very pronounced curling?

Sincere thanks and appreciation for any experience and expertise you choose to share.

Andy.

 

That doesn't look healthy at all. I have an Acer palmatum "Taylor" growing in compost and it is very healthy though it is in the ground and not in a container.

 

Hi @Head Gardener's Dogsbody
I'm no Acer expert however I had a very similar one for a good few years in a pot and it was very happy until spring this year when after coming into leaf for a few weeks did exactly the same and died. I emptied the pot and went through the soil and it was full of vine weevil grubs. There was no notches or visible damage to the leaves before hand. It might be worth just having a look.