Technical Abstract: Weed control in blackberries (Rubus spp.) is a serious problem for organic producers and those who wish to reduce their reliance on herbicides. Three landscape fabrics (Dewitt, Texel, and a white polyester weave) and one industrial grade white on black plastic were used in conjuction with newly planted ‘Kiowa’ root cuttings in Feb. 2006. In the no-fabric treatment, weeds were controlled by hand. The reflectant white plastic and weave weed barriers reduced mid-summer soil temperatures at 10 cm and reduced the magnitude in soil temperature fluctuation. None of the weed barriers had an effect on soil water content measured at 0 to 20 cm. Plant vigor and height were improved by use of weed barriers. White plastic improved the cumulative season yield by 30% in 2007 compared to other barriers or bare soil. Fruit from bare soil plants showed the greatest decline in average fruit size during the picking season. Fruit from plants grown in bare soil were lowest in soluble solids and sugar:acid ratio compared to fruit from weed barrier treatments. Fruit grown over white plastic had the highest mean soluble solids and sugar:acid ratios; both reflectant weed barriers improved berry anthocyanin levels.