Stefan Buczacki solves your plot problems
Jim Phillipson, by email
Stefan says: Not if you can avoid it. But I appreciate your dilemma because there isn’t an infinite amount of room in a garden and all types of soft fruit require sunshine and good soil and, collectively, are rather extensive. Yet fruit bushes and canes must be replaced periodically. The effective productive life of most types of soft fruit (gooseberries are exceptions) is generally under 10 years.
The reason why soft fruit plants have a limited productive life is because they begin to accumulate virus contamination after a few years and this gradually saps their vigour and reduces their yield. Some of the viruses are introduced into the plants by aphids and some by soil-inhabiting eelworms, and a large population of these eelworms will be left behind in the soil when the old fruit plants are removed. They’ll rapidly invade the roots of the new stock, shortening their productive life appreciably, and sometimes even making it all but impossible for them to establish properly. In time, the eelworm population will die away and/or the amount of virus present in the soil will be diluted significantly. But you can’t rotate a whole fruit cage as you can a vegetable plot (or even a strawberry bed) and if there really isn’t another suitable position in your garden, then replace as much as possible of the soil in the existing position.
This soil replacement isn’t as tough as you might imagine. Dig out the new planting holes fairly generously, then swap the soil with corresponding barrow-loads from the vegetable garden, and your new plants should be fine. This is only likely to be necessary every eight years or so and the rewards of doing the task properly can be seen in the immeasurably better fruit crops. The virus and eelworms will do no harm in the vegetable garden.