It’s hard to see from this photo, but this is a multi stemmed apple tree which orignally fell some time ago – fallen apple trees being a common sight in Cornwall. It has regrown from where it fell at several points, creating it’s own new root systems completely disregarding the original rootstock it had previously grown on.
This has happened because some west country apple varieties can be grown as ‘pitchers’ or as ‘own root’ trees. Other apple trees cannot do this and need to be grafted. ‘Own root’ trees can be grown from cuttings taken now when carrying out annual pruning.
The draw backs with own root trees are that the final size and vigour of the tree will vary depending on the variety and the pest and disease resistance will vary too. In contrast, the vigour and disease resistance of known traditional rootstock size, onto which a tree is normally grafted, has been bred and sold commercially due to these particular characteristics and therefore are known and usually chosen for this reason. If a tree has fallen and regrown on it’s own roots – as in the orchard above where we were pruning this month – then the tree may outgrow it’s space more quickly if of great vigour than the original rootstock. The size will impact the other trees surrounding it and also your ability to harvest the fruit. The final size will be dependent on the variety but could be up to the size of a wild crab apple tree – say up to 8-10 metres tall. But equally
However, there are many benefits to having one or two own root apple trees in your orchard. Grafting obviously creates a weaker tree in some ways, as you are splicing two trees together, the resulting wound does create some stress on the tree. Growing an own-root tree will generally result in a healthier and stronger apple tree without this area of weakness created through grafting union. Mary Martin and James Evans, of ‘A Cornish Pomona’ have been experimenting with ‘own root’ trees for some years and the range of characteristics of vigour or pest and disease resistance varies between the varieties.
There is more information on this fascinating topic researched by Hugh Ermen on the Orange pippin website and also here at an apple farmer website.