First Paragraph: I am sure none of you need to be reminded of the importance of vine nutrition in producing the highest quality winegrapes and therefore the highest quality wine. However, despite its importance there are many indications that we have much to learn about how to achieve good vine nutrition. One of the most obvious is the fact that the nitrogen critical values in petiole samples established by University research many years ago no longer seem to apply, according to many growers, PCAs and consultants that I talk to. That is because the rootstocks and clones being used now are different to the ones used years ago when the critical values were established. Furthermore, there are arguments over what tissue should be used for vine nutrient analyses, petiole or leaf blade. Then there is the argument over the effectiveness of foliar application of fertilizers vs. soil application or fertigation, not to mention the argument over the best time to apply fertilizers, in what amounts, and how often.
