2004 Annual Report 4.What were the most significant accomplishments this past year? D. Progress Report: This report serves to document research conducted under a non-funded cooperative agreement between ARS and the University of New Hampshire. Additional details of research can be found in the report for the parent CRIS 1931-21000-012-00D, Small Fruit Production Systems. A field plot containing 'Siskyou', 'Boysen', 'Navaho', and 'Triple Crown' blackberries was established at the University of New Hampshire Horticulture Farm near Durham, NH, and the rotatable cross-arm (RCA) trellis and conventional single post trellis systems were installed. The purpose of this project is to develop novel blackberry cultural techniques to mitigate low temperature damage. RCA trellis system permits canes to be positioned close to the ground and allow winter protection material and snow to cover the canes. Insulation of canes by winter protection cover and snow will minimize exposure to low temperatures and improve bud survival. An effective winter protection system will help farmers to grow blackberries in northern states.