By Sbocajaerdna
United Kingdom 
Dear gardener,
We have three blackcurrant bushes in the back of the garden. They are well established, but we dont know how old they are as they were here when we moved in.
This year two of the bushes are 'sick'. The leaves are shrivelled, the leaves are spotted with yellow, the branches have a kind of white/yellow moss on them. The plant flowered but now the berries are either very small or the place where they should be is brown and dead. The third blackcurrant bush, has big green leaves, and big healthy berries. We did cut all of them back in the spring - as adviced, removing the diseased wood, and any crossing branches.
What can we do to help the other two berry plants? Do you think the third berry plant will be affected by the two sick ones?
Thanks for your help.
29 May, 2011
Answers
Nothing to do with the problem, but in future I would prune blackcurrants immediately after finishing picking the fruit. They will fruit on new growth made the previous year, and pruning then encourages new stems from lower down the bush than if you left it until later. Pruning in spring will remove some of the wood which would have fruited. Once the bush is established , aim to remove one or two old stems from low down each year , to encourage new growth from the base of the plant.
I wonder whether perhaps your sick bushes may have been attacked by the reversion virus, for which there is no cure, though this normally results in small but green leaves not yellow ones. Photos would help.
29 May, 2011
You haven't said where you are in the UK, so I don't know how likely it is your plants could be affected by drought. I know that sounds counter intuitive because you've got one healthy plant, but perhaps its in a spot which doesn't get so much sun, or has other environmental factors which mean it doesn't dry out so much. So more info please...
29 May, 2011