Mature Cabernet Franc Vine and Groundcover Ecosystem Response to Vineyard Aisle Managed Cover Crops

Traditional vineyard floor management in humid regions consists of mown perennial grass or mown resident vegetation in aisles. Many vineyard sites in the eastern USA have climate and soil that support excessive vine vigor and rapid growth of aisle vegetation. Frequent mowing or unmanaged aisles are not a practical option. To explore vineyard floor management options for vine vigor and weed management while maintaining soil cover, vine balance, and fruit quality in the eastern USA, seven cover crop treatments: 1) grower control mown tall fescue (Festuca arundinacea L.), 2) chemically mown tall fescue (Festuca arundinacea), 3) little barley (Hordeum pusillum Nutt.), 4) downy brome (Bromus tectorum L.), 5) oilseed radish (Raphanus sativus L.), 6) spring oats (Avena sativa L.), 7) chemically mown sorghum-sudangrass (Sorghum bicolor L. Moench sp.) were established for the 2011 and 2012 growing seasons in a commercial Cabernet franc vineyard, planted in 2000, in southern Illinois, on an Menfro silt loam soil. In fall 2011, oilseed radish reduced the fresh weight of grapevine shoots removed with summer hedging 46% compared to the grower control. In 2012, spring oats increased the weight of grapevine shoots removed with summer hedging 160% compared to the grower control. In 2012, spring oats, and chemically mown sorghum-sudangrass produced 82% and 73%, respectively, greater pruning weights compared to grower control mown fescue, also, spring oats, downy brome, and chemically mown sorghum-sudangrass produced 54%, 48%, and 50%, respectively, greater yields compared to the grower control in 2012. Cover crop did not affect Ravaz index in 2011 or 2012. Chemically mown sorghum-sudangrass reduced total soluble solids in grape must 7% compared to the grower control in 2012. Downy brome produced the most ground cover and greatest weed control at bloom time in 2011 and 2012, and harvest time in 2011. In 2012, oilseed radish at veraison and harvest time produced 97% and 177%, respectively, more ground cover than grower control. The persistent mulch produced by little barley and downy brome followed by burndown herbicide, Rely ® (glufosinate 1 lb ai/gal) 76 fl oz/acre in August reduced their average weed cover by a range of 99% to 89% compared to all other treatments except grower control at harvest 2012. Downy brome established in vineyard aisles had the greatest potential for maintaining weed control at bloom and harvest time, while increasing yield without decreasing vine size. However, more research is needed to develop a residue management program which encourages self-reseeding of downy brome and little barley. In a season with above average rainfall, oilseed radish reduced excessively vigorous vine growth. While all treatments studied had the potential for vineyard use, downy brome and oilseed radish had the most potential to be readily incorporated into practical vineyard aisle management systems provided they are managed to produce moderate vine size, without adverse effects to yield or fruit quality, while still maintaining effective weed control