Effect of Harvest Delay of Southern Highbush Blueberry on Resistance to Impact and Storage Quality

Fresh-market blueberries (southern highbush hybrids) are typically hand-harvested every 3 to 4 d during the picking season. However, in order for the fruit to be suitable for mechanical harvest, the harvest interval would need to be extended to every 7 to 10 d. This extended delay to harvest might cause fruit abscission or significant loss in quality. Additionally, the fruit experience several impacts during mechanical harvest; the most severe is when the fruit is detached from the bush and falls to the catch plates on the harvester. This initial impact is believed to be the major cause of fruit softening during storage. In each season in 2011 and 2012, individual fruit from ‘Star’ and ‘Sweetcrisp’ bushes were tagged at color break stage and fruit color was tracked. Half of the fruit were hand-harvested upon reaching blue stage and the remaining fruit were harvested 7 d later. At each harvest, 20 fruit/cultivar were individually dropped once from 60 cm and held for 3 d at 5 °C to evaluate softening. The remaining fruit were stored in commercial clamshell containers (n = 50 fruit) at 1 °C and evaluated after 7 and 14 d. Fruit most resistant to the impact were from the early harvest (EH) and from year 1; ‘Sweetcrisp’ had fewer soft fruit than ‘Star’. From the storage tests, ‘Sweetcrisp’ typically had fewer soft fruit and less shrivel than ‘Star’ for each treatment comparison. The EH fruit generally had fewer soft fruit than late harvest (LH) fruit, whereas there was variable effect on shrivel. Fruit from year 2 had higher soluble solids content than year 1, and LH ‘Star’ fruit was 3 to 4 ° Brix higher than EH. For both seasons, however, total titratable acidity was consistently 40% to 50% lower for LH fruit and for both cultivars, making the Brix : acid ratio consistently higher for LH fruit. The treatments had minimal effect on overall appearance and there was no decay.