The first few years we rarely did any pruning as we were busy planting more plants and they just needed to grow. But as the plants age they need cutting back so that they are not out in the rows too much and can get damaged mowing.
According to the Agriculture Exchange office, with Rabbiteye variety you should prune more vigorously beginning at about the 6th year, remove between 10 and 15 percent of the canes each year (generally 1 to 2 canes) by cutting the oldest canes off about 2 inches aboveground.
We now prune every year to clean up the rows and keep down disease. We also use the cuttings to cultivate our own new plants. We are just now getting good at this process. Thanks to Kelly we tried dipping it into a hormone that encourages root growth. This was very successful.
It is best to cut late fall or early spring from the new growth before the buds break. You will want a pencil thick cutting about 4-8 inches long. We found using a commercial hormone more successful than just dipping into water and putting it into a pot of peat.