Is my apricot tree sick?

Diggers Member:

Hello, this is a dwarf apricot that has been in the ground for nearly 2 years and which flourished last year.  This year it flowered perfectly, began to come into leaf normally and then became very sick.  Stunted new growth, green leaves turning yellow from the edges, and new growth dying off.

A Rosa mutabilis next to it was also very sick this spring with similar symptoms.

I use no pesticides or weed killers so am totally baffled.

The ground is Northcote clay under some good topsoil and I have added compost and fertiliser in recommended ways.

I would be so grateful to know what has happened. 

Hort Advisor:

Hi Member,
Are you able to test the soil pH?  Is the soil water logged at the moment?

Diggers Member:

The bed that the apricot is growing in is about 20 square metres and as I said earlier was probably under concrete for 30 years, and was then trampled on by builders for another year. 

The soil here is extremely clayey and I did put a lot of compost onto it two years ago when the bed was created.  However I have now tested the whole are twice using a tester that gets down below the surface and there are patches where the pH is 3, others 4, perhaps larger spots that are 5.5 and one or two are 6.

The apricot looks really terrible and I can’t see it recovering this summer – though I would be interested in what you think.  It is there temporarily while an Anzac peach grows up which was planted the winter before last.  It looks alright so far, but I am very keen to fix the soil so that it will survive long term once its roots get down further.
Otherwise, the plants are perennials which mostly seem to be alright so far.
So my main question is how I can best increase the pH level of the soil generally to above 6.   Dolomite?  Mulches?

And in the meantime can I compensate for any difficulty the plants have in accessing nutrients by feeding more by something like a season leaf spray?

And do you think such a low pH suggests some other problem with the soil?

Hort Advisor:

Hi Member,

Working with soil that has been under a slab for many years is problematic as you are finding. 

It sounds like the soil is very compacted as you say which will add to the problem as plants also need air pockets in the soil. 

Really thorough preparation before planting with loads and loads of compost, some gypsum and in your case aerating the soil too or forking into the compacted layers to allow air and moisture to penetrate. 

Without lifting the existing plants, the best thing you can do is to continue to add compost, compost and more compost.

This will encourage all sorts of soil microbes and nematodes to come and help do the underground work for you and open up the soil by adding tunnels and slimes.  It will be slow going but probably the only way to go. 

• Adding Mychorrhizal fungi with Mycogold may be useful too.   

• Adding Gypsum to the clay layer may be effective but really needs to be done directly to the clay before you plant etc.  

• Lime may also increase the pH but is best done when improving the soil so it can be blended through. 

• Seasol will not hurt and nor will a liquid complete fertiliser.  See if any of that helps. 

Fingers crossed.