Blackcurrants are infested with aphids

I have grown blackcurrants for a number of years, but this is the first time I’ve seen them infested with what I assume are black aphids. What can I use to get rid of them? Will the blackcurrants be safe to eat once they’ve matured?

There are several types of aphid which affect blackcurrants. The most common is the blister aphid which causes the leaves to produce blisters or puckered areas which turn reddish and can eventually die.
Other, more familiar sap-sucking aphids can appear as greenfly or blackfly and multiply into large colonies. As well as damaging tissue and weakening plants, they can carry virus from one bush to another.
If you prefer not to use chemicals, there is little you can do, other than trying to destroy as many by hand as possible, rubbing them off the plants. An organic, soft-soap spray could also help.
You can also control aphids with insecticides. Be sure to obey the instructions on the packet, and to leave the necessary interval between treatment and harvest. For blister aphid, a winter wash such as Growing Success Winter Tree Wash will also destroy the aphid eggs.