Fruit also controls tree height. The VA system should not be headed until fruit is at the top of the tree, and the leader has been pulled down with the weight of the fruit. At this point, perhaps year 5 or beyond, the top can be reduced in size to allow better light exposure to the lower limbs. There are many different kinds of trellis systems being used world wide. Some are extremely formal in design and require detailed timely management.
Trellis systems involve the positioning of limbs along the supporting wires.
This positioning can be done at any time the work load permits. Horizontal positioning is the most productive and limbs that are growing into the travel row can be either bent back in line or removed. Pruning is kept to a minimum to reduce vigour. Shoot growth is allowed to proceed unmanipulated until mid-July. At this time shoots are secured to the support lattice using quick, inexpensive tie materials.