Gardening - Fruit: Maintenance
Brambles include raspberries and blackberries, plus many hybrids of the two. Although the term bramble indicates thorniness, both thorned and thornless bramble varieties exist. Likewise, some brambles have an erect growth habit, while others are classified as semi-erect and even others as trailing. In Tennessee, erect and semi-erect brambles are widely grown, but very few trailing brambles will be found.
Proper pruning and training of brambles require knowledge of their growth and fruiting habits. The root system and crown of brambles are perennial, meaning that they will live for many years, while the canes are biennial. The first year of their two-year life cycle is referred to as the “primocane year.” During the primocane year, a bramble cane grows and initiates fruit buds. The summer of the floricane year, canes bloom, set fruit and then die following fruit ripening (Diagram 1.) In an established bramble planting, primocanes and floricanes exist at the same time. Everbearing raspberries deviate from this pattern somewhat. They will be discussed later.
Pruning and training are distinctly different operations, yet they are often used together to achieve a desired effect. Pruning refers to making cuts on canes to promote growth in certain areas, to adjust crop load, to increase fruit quality and to remove pest damaged tissue. Training involves positioning canes to achieve a desired effect. Trellising semi-erect brambles is a good example of training. Together, pruning and training have many positive effects on yields, fruit quality, pest problems and ease of management. In a new planting, pruning is used to enhance plant survival and growth. Training is used to support new primocanes, especially with semi-erect varieties.
In subsequent years, proper pruning can lessen pest problems by removal of diseased, insect-infested and dead canes. Light distribution, air movement and spray penetration throughout the canopy will be better in a well-managed planting, resulting not only in a reduction of pest problems, but an increase in yields and fruit quality. Proper pruning and training make management of the bramble planting easier as well.
"SP284-G-Pruning Raspberries and Blackberries in Home Gardens," The University of Tennessee Agricultural Extension Service, SP284G-5M-4/99(Rev) E12-2015-00-047-99, http://trace.tennessee.edu/utk_agexgard/3