Vineyard floor management in the Finger Lakes region: physiological and microbial perspectives
Excessive vine vegetative growth in wet, cool climates increases management costs and compromises grape quality. However, the standard practice of bare soil under vines exacerbates the vigor problem. Previous studies found that using under-vine cover crops reduced vine vigor in young vineyards but had little to no impact on mature vines. Wine sensory properties were impacted by under-vine cover crops although the cause was not clear. A study conducted in a mature Cabernet franc (Vitis vinifera L.) vineyard in the Finger Lakes region showed that chicory was the most effective cover crop to consistently reduce pruning weight and canopy leaf layer number without reducing yield compared to glyphosate maintained bare soil, whereas other under-vine cover crop treatments were not as consistent. In a three year study conducted in a mature Riesling (Vitis vinifera L.) vineyard, under-vine natural vegetation reduced vine canopy leaf layers and occlusion layers in one of the years compared to glyphosate maintained bare soil but there were no detectable sensory differences among wines from different under-vine floor treatments in any year. Profiling of soil microbiome using high-throughput sequencing showed that microbial community of natural vegetation diverged from the cultivation and glyphosate maintained treatments. However, no corresponding change in fungal community structure was observed on grapes or in simulated spontaneous fermentations. Undiscernible wine sensory properties also confirmed the lack of treatment effects in wines. Although under-vine cover crops impact on vine vegetative growth varied, no reduction in yield suggested that under-vine cover crops could serve as beneficial alternatives to bare soil for sustainable vineyard management. Further studies on how under-vine cover crops impact wine sensory properties are required to evaluate their practical adoptability.