To cut or not to cut: the role of extension growth in fruit quality

Cherries are a sweet fruit, with total soluble solids being a key determinant of quality in most fruit quality studies. It is also well known that leaves play a role in delivering assimilates to fruit, and that fruits are strong sinks. Less well known is the role of extension growth (current season shoot growth) on fruit quality. Extension growth occurs throughout the fruit growing season and has the potential to be a strong source of assimilates. However, while growing they can also be a strong sink; hence the question; to cut or not to cut? Summer pruning can be useful to reduce vigour, or promote light interception but can it also be used to reduce competition for assimilates between growing fruit and extension growth? Trials assessing fruit quality from trees (cvs. ‘Kordia’, ‘Sweetheart’ and ‘Satonishiki’) which had been pruned at various times throughout the growing season were undertaken. Timing had a significant impact on fruit quality with pruning after, but not at, Stage II increasing fruit sugars (TSS). Pruning at most stages had no impact on sugars in newly developing buds. Pruning during Stage III increased current season fruit sugars. Pruning did not affect the uniformity of bud burst or yield in the following season. Therefore, used appropriately, summer pruning of extension growth may be a useful tool in promoting sugar assimilation. Furthermore, pruning during rainfall in the three weeks prior to harvest maturity reduced fruit cracking, while pruning prior to rainfall in the same period did not impact on cracking. This implicates a role of extension growth leaves in the supply of excess water to the fruit reducing both yield and quality such that pruning could increase both yield and quality