In this You Tube Video, Barbara Jones, a blackberry grower in North Carolina, is explaining how they manage the shift trellis. This shift trellis was developed by the late Dr. Herb Stiles, at Virginia Tech Univ. The basic premise of the shift trellis is to have all the fruit on one side of the canopy during harvest, where it is all one side of the row and is not exposed to the sun for the entire day. This is achieved by horizontally positioning the trellis during flowering, so that all the flowering laterals grow up towards the sun. Then when the fruit is set and starts to grow, the trellis is moved to the one o'clock position. This video was shot in early February 2011.
Although the Jones are primarily sweetpotato gowers, they have about 5 acres of blackberries that for the past 2 years have been sold to Trader Joes. CLICK ON THIS LINK TO SEE VIDEO:
Here is a shot of fruit that is starting to get ripe in late May 2011.