Whats wrong with my thornless blackberry?

[Sgorad]

The leaves of my thornless blackberry are discoloured. It is growing against a South wall in a half barrel, in peat free compost and home made compost. Thinking nutrient deficiency or perhaps virus. It’s called ‘Thornfree’ and this is it’s first year. Hope you can help thanks.

 

[Marck]

This does look like a metal nutrient deficiency, most likely iron. Have you already fertilized the plant? If not, apply a complete fertilizer in a fast-acting form, and then wait and observe the new growth. The already yellowed leaves often will not improve, but the new growth should come in healthy. Specialty fertilizers and chelates probably aren't necessary in a container situation, but can be considered if the problem persists.

Proper watering and drainage can also affect nutrient availability. I presume there are a number of drainage holes in the barrel. Let the potting soil partly dry between watering to insure air to the roots.

 

[Sgorad]

Thank you for that. I was really worried it might be a virus. The newer leaves are green, I have given it a couple of seaweed liquid feeds. There are plenty of drainage holes, perhaps too many for a South facing wall, even in North Wales. Much appreciated.
I see you are in California, it’s heartbreaking to see news reports of those beautiful forests burning, people and wildlife fleeing their homes.

 

[Marck]

Yes, climate change is truly the biggest problem the world now faces. There is no reason to think it will not get worse year by year.

 

[DirtMechanic]

Yes, climate change is truly the biggest problem the world now faces. There is no reason to think it will not get worse year by year.

I have changed my opinion to include the federal sales taxes on imported goods known as tariffs to be a driver of this problem. An idea that stretches to unregulated countries producing cheap products and brown air while we get the clean part of the transaction, no manufacturing base to pollute and increases in tax revenue.