Submitted to: International Journal of Fruit Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/23/2011
Publication Date: 10/1/2011
Citation: Makus, D.J. 2011. Use of synthetic ground covers to control weeds in blackberries. International Journal of Fruit Science. 11(3):286-298. Interpretive Summary: About 18,000 acres of blackberries are grown in North America. Weed control is a serious problem for organic producers and those who wish to reduce their reliance on herbicides. By using durable landscape fabrics and an industrial white-on-black plastic, weeds were completely controlled in the first two fruiting years and fruit yield and berry quality improved compared to the non-fabric control. This should result in lower production cost to the producer, less reliance on chemical and mechanical weed control and improved berry quality. Two of the fabrics tested are expected to last for several years.
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 for weed control in conjuction with newly planted ‘Kiowa’ root cuttings in Feb. 2006. In the no-fabric treatment, weeds were controlled mechanically 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 during the establishment year. In a separate greenhouse container study in 2008, when weed barriers were placed in pots with and without plants, pots containing weed barriers with plants, over time, took up as much water as pots with plants and no weed barrier (simulated bare ground), thus, confounding the ability to detect soil moisture differences due in part to improved plant growth (P=0.08) from the weed barriers. Field plant vigor and plant height measured in 2007 (only) were improved by use of weed barriers. Plot weed removal times were shortest for white plastic and longest for bare soil. Texel and particularly the white polyester weave degraded within two years in the field. White plastic improved the average cumulative season yields in both years (6.46 t/ha) compared to yields from plants grown in bare soil (4.58 t/ha), P=0.003, and also when contrasted against all other weed control methods (P=0.0003). In 2007, fruit from bare soil plants showed the greatest decline in average fruit size during the picking season. Fruit from plants grown in bare soil in 2007 were lowest in soluble solids and sugar:acid ratio compared to fruit from weed barrier treatments. Similar, though non-significant, fruit quality trends existed in 2008 harvested fruit. In both years, fruit grown over white plastic had the highest mean soluble solids concentration (11.3%) compared to bare ground-grown fruit (9.8%).