Evaluation of raspberries for tunnel and field production in North Carolina
Penelope Perkins-Veazie and Gina Fernandez
Raspberries are a highly popular fruit with consumers, and also a high value crop for producers. One of the major limitations to production in North Carolina is heat. Raspberry plants often respond to heat stress by reducing fruit size. Also, the warm temperatures encountered during harvest can lead to a very short postharvest loss, as berries are softer and easier to bruise when harvested warm. In this multi-year study, raspberry cultivars and NC breeding selections were evaluated in high tunnel and field production systems.
Harvest and Handling: Pick firm fruit and place in shallow vented containers. Red raspberries can be harvested when pink and come off the plant with minimal tugging. The most often used container is a plastic ½ pint with vents in top, bottom, and sides to aid air flow. Containers for raspberries should be shallow, as only a few layers of berries should be in the box to prevent fruit collapse and leaking. The best time to pick raspberries is early in the morning, while fruit are still cool. Picking wet raspberries after rainfall or heavy dew is not recommended as the shelf life quickly drops.
Raspberries can be cooled at temperatures slightly below freezing (31 F) as the high sugar content acts as an anti-freeze. It is better to cool fruit soon after harvest and hold raspberries below 40°F as long as possible. If cooling is delayed, storage life is lost in proportion to the delay (a one hour delay can mean a one day loss in shelf life).
Best cultivars and selections for postharvest life when grown in North Carolina. These suggestions are based on several years trials at research stations in NC. Check http://rubus.ces.ncsu.edu for yield data of these selections and cultivars. Note that some yield data is still being collected in fall 2014.
10-14 day shelf life if held at 35°F within 2 hours from harvest
7-10 day shelf life
For local use only (less than 5 days)