Training trees as an espalier (a main trunk with neatly pruned horizontal branches on either sided) is fine for apple trees but quinces are better trained in a fan shape as they dont respond well to such restrictive pruning. Its also worth checking that the apple tree is spur-bearing (bears fruit all along the branches) rather than tip-bearing as you wouldnt get very many apples on an espaliered tip-bearing tree!
1. Firstly put in a sturdy support framework. To train the apple tree, place wire or bamboo poles horizontally between two posts, spacing the wires or poles 45-60cm apart.
2. This winter, cut the leading shoot of your apple tree back to a bud about 5cm above the first wire. Make the cut just above the bud.
3. In the summer, a new leading shoot will grow which needs to be tied in. Also choose two strong side shoots to tie in either side of the trunk, along your first set of wires. Prune back any other side branches to two or three leaves.
4. Once the tree has become dormant again next year, cut the new leader back to a bud about 5cm above the second wire and completely remove all the side shoots that have been shortened in the summer (leave the two selected side shoots on the first wire).
5. Again in the summer tie in the new leader that will be produced, and two more side shoots along the second wire. Remember to shorten any other shoots.
6. Continue the process until there are three or four tiers. The branches on the first wire will start fruiting before the topmost ones have finished developing. During the summer, prune new shoots on the lower branches back to three or four leaves to maintain a neat shape and help develop fruiting spurs.
7. Remove the leading shoot once there are enough tiers on the espalier. Only winter prune the espalier when there is a need to remove congested fruit buds (spurs).
For Quince trees it would be better trained as a fan as this is not so restrictive on growth:
1. Prepare a support framework as for apples. Select two side shoots, one on either side of the trunk and growing about 30cm from the ground. Cut out the leader just above the two side shoots.
2. Shorten the two side shoots to about 40cm length and tie them to bamboo poles at a 40? angle (so that there is a shallow V shape). Cut off any other side shoots on the main trunk.
3. In the summer tie in any well placed shoots that develop, aiming to create a fan shape spreading across the framework. The aim is to fill in the centre of the fan last. Only remove any crossing, badly placed or excessively vigorous shoots.
4. As for apple espaliers, in the summer prune new shoots on the established branches back to three leaves
5. As the quince matures, older or congested fruiting spurs can be pruned out during the winter.