Leaf nutrient analysis: Do we need to refine the current sampling protocol?

The nutritional analysis of leaves is an invaluable tool for determining vine nutritional status and managing vineyard nutrition. The current nutrient analysis protocol suggests collecting petiole samples from opposite bunches at 80% flowering with a sample size of at least 100 (AWRI2010). Current standards for Australian grapevines are based on Californian data that were subsequently updated for Australian conditions across a range of cultivars (Reuter and Robinson 1997).However, the current recommended standards for optimum levels of each nutrient in petiole/laminae is not cultivar specific. Also, it is unclear how much variation there is in leaf nutrient status within the bunch zone. As part of a Wine Australia-funded, three-year project we conducted a study aimed at optimising the tissue sampling protocol and to explore the differences in nutrient levels between varieties and tissue types.