It is essential that apple trees produce sufficient flowers to set an optimum crop of fruit in relation to the size of the trees. It is also vital that these flowers are of sufficient quality to set fruits reliably and to produce large fruits of good texture and storage potential.
On young newly-planted trees the objective is to induce quality flowers on the trees in the second and third years after planting i.e. to improve their floral precocity. If orchards are to break-even rapidly and move towards profitability on the investment, cropping early in the orchard’s life is essential.
On mature trees, lack of abundance of flowering is a relatively rare problem and usually only occurs with varieties that are prone to biennial bearing. Fortunately, most of the traditional varieties suffering from this problem (e.g. Miller’s Seedling, Laxton’s Superb) are no longer grown commercially, but Elstar can become strongly biennial in its cropping. The varieties Cox and Braeburn are weakly biennial. However, flower quality is often a limiting factor in fruit set and retention on mature trees.
Occasionally, excessive flowering and inadequate new extension growth may be a problem with some varieties grown on dwarfing rootstocks such as M.27 and M9 on replant soils. Here the objective must be to reduce the abundance of floral spurs and increase shoot growth, so as to bring the trees back into a more optimal balance of fruit production with shoot growth.