2005 Annual Report 4d.Progress report. This report serves to document research conducted under a non-funded cooperative agreement between ARS and the University of Maine. Additional details of this research can be found in the report for the parent CRIS 1931-21000-012-00D, Small Fruit Production Systems. Siskiyou Boysen, Navaho and Triple Crown blackberries were potted and will be grown outdoor and in a plastic house at the Maine Agricultural Experiment Station in Manmouth, ME. The rotatable cross-arm trellis and conventional single post trellis systems will be installed. Winter protection treatments will be applied in the fall. 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 the winter protection cover and snow will minimize plant's exposure to low temperatures and improve bud survival. An effective winter protection system will help farmers to grow blackberries in northern states.