Is something wrong with my thornless blackberry?
Linzey Friend, by email
Stefan says: Your thornless blackberry was planted approximately 10 years ago and generally gives a good crop but over the past few years the fruit on several branches has been malformed, with small, poor-tasting berries. You don’t think it’s due to a lack of water, and nor do I, not least because you have given me some most helpful additional information. You say you rooted a cutting from one of the affected branches and the fruit it produced were the same.
You are correct, therefore, in deducing this to be a plant health issue and the explanation is that the plant has been contaminated with one of the many viruses that affect soft fruit. This is almost inevitable after 10 years and cannot be cured. The only recourse is to obtain a new, virus-free blackberry from a reputable supplier and plant it somewhere well away from the present position.