Issue link: http://read.dmtmag.com/i/267019
w w w. v w m m e d i a . c o m M a r - A p r 2 014 | V I N E YA R D & W I N E RY M A N A G E M E N T 3 1 ield management is about cultivating vine health and balance. Grapegrow- ers should promote sufficient vine growth to produce and ripen a reasonably sized crop. However, excessive vigor can cause problems with floral initiation and fruit set, thereby reducing yields and rais- ing issues with shaded underripe fruit, increased risk of diseases, and other qual- ity issues. High-quality wine grapes come from vines that have a healthy balance of crop as excessive yields lead to diluted, under- ripe wines. But lower yields are advanta- geous only up to a point. Yields that are too low given the canopy development can be problematic, as sugar accumulation can outpace other ripeness indicators such as phenolic development, and malic acid and pyrazine degradation. Yield management begins with site selection. Sites with deep soils that are rich in organic matter and have good water-holding capacity intrinsically have a higher production capacity than sites with shallow soils, low organic matter and rapid drainage. However, many factors influence vineyard productivity, beginning with choic- es made during vineyard development as influenced by site and the grower's goals. During land preparation, soils should be assessed for any factors that may be limit- ing to production. Shallow soils and those with a shallow hardpan or barrier layer can be deep-ripped with a winged tine to increase rooting depth. Compost can be incorporated into the soil to increase organic matter and nutrient supply. If soil pH or chemistry may be limiting factors, soil amendments such as lime or gypsum should be considered. Variety and clonal selection significantly affect yields, although site characteristics and winemaking goals should take prece- dence when selecting variety, clone and rootstock. There is tremendous genetic diversity among the different varieties within the single species of vinifera, with a wide varia- tion in yield. Pinot noir, for example, tends to be lower yield- ing with small clusters. G r e n a c h e i s k n o w n t o be a heavy producer that requires extensive crop removal for high-quality production. Malbec is an inconsistent producer, with a range of yields depending on climate conditions and vineyard practices during set. Even within a variety, there can be significant dif- ferences in clones. ROOTS OF THE MATTER R o o t s t o c k s e l e c t i o n plays an important role in vine capacity, as vigorous rootstocks will create a more robust vine. In trials using the same scion mate- rial, the effect of rootstock + Yield management begins with cultivating a healthy vine, but excessive vigor can actually cause lower yields. + Choices made during vineyard development will impact yields for the life of the vineyard. + There is a complex, dual- year effect on fertility and yields, since bud differential begins the year prior to growth. + Pruning decisions, canopy management, disease pre- vention, irrigation and fertil- ization all impact crop yield. AT A GLANCE Vines in Balance Yield management has a direct impact on wine quality SOIL & CELLAR REMI COHEN Site selection, including the depth and richness of the soil, is one of many factors that influence yield management. Photo: Creatas Images/ Thinkstock