Developing a low-input under-vine management system to improve profitability without compromising yield or quality

The under-vine region of the vineyard floor contains the greatest concentration of vine roots, so management of this zone directly impacts vine yield, quality and profitability. The removal of weeds involves regular use of herbicides or cultivation, neither of which is recognized as best practice soil management. Resultant herbicide resistant weeds, poor soil quality and restricted access to soil moisture may adversely affect vine growth. Under-vine cover crops are being compared with herbicide and straw mulch controls for their impact on yield, fruit, wine and soil quality, suppression of weeds and economic response at five sites in South Australia. The cover crop species consist of annual and perennial native or exotic grasses and legumes.

Despite under-vine cover crop biomass of up to 8 t/ha following a very dry spring, at some sites treatments showed improved grape yields in 2016 compared with the herbicide and straw mulch controls. Different cover crop species had distinctive effects on grapevine root colonisation by beneficial arbuscular mycorrhizal fungi (AMF). Next Generation Sequencing of the vineyard soil showed that some cover crops were more strongly associated with Glomeromycota, the fungal division containing the AMF. Fruit quality was not compromised by the cover crops, and in a sensory analysis of Shiraz wine from the Barossa site, the herbicide control was rated lowest of seven treatments. Perennial cover crops which remained active over summer helped to suppress summer weeds but also reduced yields at most sites. In this paper we report on results from one selected site.