Acer Help Needed

[Garden Manager]

I have a small collection of Acer palmatum (Japanese acers) all in pots. One mature one doing very well plus 3 small ones I bought a couple of years ago. All were doing fine until a few weeks ago when the leaves on one started going brown and dying, I have carefully removed these and the plant itself still seems to be alive, however no new growth has yet appered. Now this morning I have noticed a second plant going the same way.

The plants are grown in pots of ericaceous compost in a cool shady part of the garden. They don't appear to have dried out, nor does it appear at any time that they have become waterlogged, at least not recently. The compost is as it should be, damp but not wet. There seems to be no sign of pest damage or any problem with the roots that i can see. I am mystified as to the cause. I still have 2 other plants that appear healthy. I do not want the same thing to happen to them!

So any ideas as to what might have caused this? Can the plants be saved and how can I stop the other healthy plants suffereing the same fate?

[Garden Manager]

[Tee Gee]

An extract from my website:

Variegated cultivars need partial shade to prevent sun scorch.

Red-leaved cultivars need some sun to develop their characteristic rich coloration.

Green-leaved cultivars will tolerate full sun but in hot conditions may scorch.

The most common problem leaf scorch, is when the foliage turns brown late in the season particularly around the margins and veins, then curl and shrivel.

This is caused by water being lost from the leaves faster than the roots can take it up.

It is not necessary to prune back unless the stems are damaged.

Such conditions do not usually kill plants, but those that show the symptoms should be well watered and sheltered even if this means erecting a temporary wind break.

Various factors can cause scorch, e.g. frost, drought, drying winds, hot sun and even salt-laden winds in coastal areas.



I think the highlighted section is most likely in your case because your plants are in pots.

The root system with your plants even with the care you are giving them is smaller (particularly the moisture seeking roots) than it would be if planted out in the border.

[Garden Manager]

I wasn't convinced that the plants had dried out, they are grown in a cool shady spot and to be honest we haven't had much dry sunny weather of late to affect them that badly.

So I investigated further and found one of the plants (at least) was very damp if not wet at the roots when the pot was removed. I should have checked this earlier. I can only conclude that the plants have suffered too much wet/moisture and have died back because of it. Its a bit strange, I have one mature acer (which is fine) that is about 10 years old and has been grown in the same location. it must have endured wetter periods in its life and not suffered by it, even when small. Yet these small, young plants apparently have not liked the recent wet spell (and possibly the wet winter preceeding it). The only difference might be is that the mature plant is a straight red palmatum and the newer ones contained some variegation, (and are in plastic pots).

What I need to know now is can anything be done to revive them? I have moved them to a more open spot in the garden to dry out a bit and apart from rain, haven't had any water. Would repotting, perhaps into clay/stoneware pots with fresh (ericaceous) compost help? Should I also do the same with the third healthy plant that is growing in the same conditions?

any other suggestions appreciated

Thanks in advance. GM

[Monika]

Have a good look at the trunk to make sure there are no woolly aphids on there sucking the thing to death.  Mine had those a couple of years ago and I was told to brush the trunk with a toothbrush to remove them.

[Garden Manager]

Have a good look at the trunk to make sure there are no woolly aphids on there sucking the thing to death.  Mine had those a couple of years ago and I was told to brush the trunk with a toothbrush to remove them.

No, no sign of them Monika. Just a sorry looking plant. Not looking good for them now. I think i have lost them ;( Unless anyone can think of anything i can try to save them?

[Tee Gee]

The plants are grown in pots of ericaceous compost in a cool shady part of the garden

What with the weather we have this year I am wondering if this might be the problem?

That is there is cool and there is shady!

I am just wondering if they have had a double helping of this this year?

I am not saying it will work but fetching them out to a warmer bright part of the garden might help, as I see it you having nothing to lose in trying!

They might be like me with my SAD syndrome caused by lack of sunshine, although the met men are predicting a heat wave later in July.

[Redalder]

Don't give up on them until they are dead. I have grown both Acer Palmatum and Tree Paeonies from seed  (Chiltern Seeds has a lot to answer for) and both can be affected badly by wet and windy weather. Somewhere drier and more sheltered might do the trick. In any case keep them until next spring before you throw them out as a small regrowth can come good. Currently nursing a sad tree paeony seedling in a new  pot in the flower bed to give shelter and moisture. Has worked before!

[Garden Manager]

Update.
The 2 afflicted plants now appear to be dead. No signs of regrowth at all. 3rd small plant plus my mature one are fine. Have repotted the surviving baby into a pot with better drainage as I am sure wet was at least part of the problem (in the absence of any other explanation).

Thanks for replies.