Blackberry problem.

[kiwiman]

Hi everyone, I have a problem that seems to occur on my blackberries. Thornless variety planted about 5 years ago. Grew lovely fruits for 3 years and the last 2 years have been puny and worthless. This is the second time this has happened , in 2 different locations of the garden. It seems as if the plant goes into a very weak state, although the growth of shoots is very strong. The variety, I think, was Himalayan giant. I have propagated a couple of new plants from the original and they have also behaved in the same manner. I've cut the lot right down now to see if it will improve the fruit size.

[rustylady]

Trouble with cutting the lot down is that you won't get ANY fruit next year. Blackberries fruit on canes produced the previous year.

[veggiechicken]

I also have a Thornless blackberry that is a complete waste of space. It flowers well and fruits appear but they look like the ones at the back of your photo - they never seem to plump up and ripen.
Mines a few years old too.
Found a photo!!

[kiwiman]

Trouble with cutting the lot down is that you won't get ANY fruit next year. Blackberries fruit on canes produced the previous year.

Thanks rustylady, I think it will be better to source a new plant and cut my losses. Beginning to think it may be a weakness of the thornless type reverting, or something like that.

[FB.]

It looks as if the berries don't have many seeds. Each "bobble" contains a seed.

So I'd wonder whether it's poor pollination?

We think of blackberries as self-fertile, but are they? Or is it that in most areas there are so many "wild" blackberries/brambles that pollination is usually plentiful.

Do you have enough bees visiting?
Are you in an isolated location?
Are your blackberries in a frost pocket (flowers being damaged)?
Are your blackberries netted and the bees can't get in?
Do you spray them (or plants nearby), and the spray kills every bee that passes through?
Are the berries in an exposed spot where bees dislike the wind turbulence?
Are the plants in a dull, damp corner that the bees don't visit? (bees love sunny, mild and sheltered).

[FB.]

I also have a Thornless blackberry that is a complete waste of space. It flowers well and fruits appear but they look like the ones at the back of your photo - they never seem to plump up and ripen.
Mines a few years old too.

Failure to go from red to black is a failure to ripen.
Usually not enough sun, or not enough warmth, or something wrong with the winter-chill requirement (winters too mild in your area) which is causing it to flower too late and not ripen in time.

I've heard a few complaints about certain soft fruits that were bred in cold climates and their failure to crop well in milder climates due to insufficient winter chill.

[veggiechicken]

Thanks FB. Its in a reasonably sunny position - about the best I can offer it! If it was just this year I would forgive it, but I've never had a decent blackberry from it - although it always looks very promising. I'll take a cutting from it and try it elsewhere - before I turf it out completely.

[kiwiman]

It looks as if the berries don't have many seeds. Each "bobble" contains a seed.

So I'd wonder whether it's poor pollination?

We think of blackberries as self-fertile, but are they? Or is it that in most areas there are so many "wild" blackberries/brambles that pollination is usually plentiful.

Do you have enough bees visiting?
Are you in an isolated location?
Are your blackberries in a frost pocket (flowers being damaged)?
Are your blackberries netted and the bees can't get in?
Do you spray them (or plants nearby), and the spray kills every bee that passes through?
Are the berries in an exposed spot where bees dislike the wind turbulence?
Are the plants in a dull, damp corner that the bees don't visit? (bees love sunny, mild and sheltered).

Thanks FB,
Can't think any of the above could be a problem in this instance though, beaten me I'm afraid. Going to try Tayberries next year in this position.

[FB.]

Thanks FB,
Can't think any of the above could be a problem in this instance though, beaten me I'm afraid. Going to try Tayberries next year in this position.

Is it possible that you have a nutrient deficiency in the soil, or an unusually high or low pH?

For example: my soil is fairly low in potassium (a side effect of excess calcium due to traces of chalk) and this means that certain of my apples (such as Golden Delicious) virtually cease flowering and completely stop cropping (and may look a little unhealthy) until I add some compost/manure to make more potassium available.

[Alison]

I used to have a thornless variety (not sure which one) and found it to be a lot less vigorous than my thorny one and they have pretty much the same conditions. A friend had the same issue so have given up on the thornless ones now - they're not that bad to pick anyway.

[FB.]

Yes, thornless blackberries generally only seem to grow about half as fast as the traditional thorny types.
The thornless ones probably being bred for low-vigour and lack of thorns to make them easier to manage.
However, I'm not sure the thornless ones would be vigorous enough to grow wild, nor grow in difficult soils or truly fend for themselves against other plant competition; rather like semi-dwarf fruit trees.

I have one of the less-thorny, upright, primocaine blackberries and so far it seems to be a very weak grower (half as vigorous as a regular thornless, and a quarter as vigorous as a thorny blackberry).
It is planted near my autumn raspberries (intending to manage it in the same way) but the raspberries are almost as vigorous as regular blackberries and will soon over-run and smother the primocaine blackberry, so it'll need moving this winter.

[kiwiman]

Is it possible that you have a nutrient deficiency in the soil, or an unusually high or low pH?

For example: my soil is fairly low in potassium (a side effect of excess calcium due to traces of chalk) and this means that certain of my apples (such as Golden Delicious) virtually cease flowering and completely stop cropping (and may look a little unhealthy) until I add some compost/manure to make more potassium available.

Hi FB, the ph is neutral and I do give a manure dressing each spring. The plant always has plenty of flowers but just does not develop the fruit fully. I have thought a bug might be responsible but can't think of anything that would be such a problem. As I said before, the first couple of fruiting seasons were fine, fully formed fruit and plenty of it. The problem just seems to have developed over the last couple of years. Do you know of any virus that affects blackberries. The foliage seems fine with no bad blemishes.

[kiwiman]

I also have a Thornless blackberry that is a complete waste of space. It flowers well and fruits appear but they look like the ones at the back of your photo - they never seem to plump up and ripen.
Mines a few years old too.
Found a photo!!
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Yes veggiechicken it does look similar to yours. I think the answer is going to be "off with its head".
It seems such a shame because it is such a sturdy plant with new shoots that grow to about 8ft every year and the thickness of a thumb. ( I've got big hands).

[sugar]

Yes, thornless blackberries generally only seem to grow about half as fast as the traditional thorny types.
The thornless ones probably being bred for low-vigour and lack of thorns to make them easier to manage.
However, I'm not sure the thornless ones would be vigorous enough to grow wild, nor grow in difficult soils or truly fend for themselves against other plant competition; rather like semi-dwarf fruit trees.

If you're looking for a vigorous, fast growing blackberry buy yourself Blackberry 'Triple Crown' . I'm not sure anything is capable of outgrowing this plant.

[kiwiman]

Thanks sugar, looks a good option if I am going to re-plant. Still thinking Tayberry replacement though.