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VINEYARD SOIL & CELLAR Fundamentals of Foliar Fertilizers Sprays can deliver quick, effective nutrients to hungry vines hen you create a vine nutrition program for your vineyard, it is important to understand the nutrient sta- tus of the vines and soils, and develop a program that is tai- lored and responds to the deficien- cies of your site and vines. This is preferable to applying nutrients on an annual basis, whether or not the vine needs them. Therefore, a vine nutrition program should involve analysis of annual tissue samples and periodic soil samples. Addi- tionally, these types of analyses can help detect deficiencies before they demonstrate themselves symptomatically. Petioles have been the industry standard for plant tissue nutrient sampling, and ranges of deficient, acceptable and excessive nutrient status have been determined for petiole analysis. Petioles have been preferred to leaf blades because SHORT COURSE Applying nutrients through foliar sprays is a quicker method than soil application. Nutrient supply from foliar sprays is more temporary. Macronutrients should be applied in larger quantities primarily through soil-applied methods. Foliar fertilization should focus on micronutrients or supplementing soil-applied macronutrients. Night sprays can be more effec- tive than day sprays. 38 VINEYARD & WINERY MANAGEMENT JULY - AUG 2012 Re-check nutrient-deficient blocks at veraison to see if additional applications are needed. also take into account vine vigor, canopy density, prior inputs, and inputs from the cover crop, as well as optimal yields. Whether you prefer petioles or leaf blades, it is recommended to use the same type of tissue in your samples, sample at the same additional applications are needed. If deficiencies are detected, a grower can choose to apply nutri- ents through the vine's root sys- tem, either by applying it to the soil or by injecting it through the drip system in a process often referred to as fertigation. Nutrients can also WWW.VWM-ONLINE.COM they tend to have less surface con- tamination than blades, and repre- sent more individual shoots and vines to make up the same amount of dry matter for a sample. Yet leaf blades have become more commonly used in recent years because nitrate nitrogen values seem to be more stable in leaf blades and fluctuate less than petioles. However, both leaf blades and petioles have their limitations for nitrogen analysis, and the deci- sion of whether or not to apply nitrogen to the vineyard should Remi Cohen is a vineyard and winery con- sultant based in Napa Valley whose primary areas of expertise include viticulture, sus- tainable vineyard management, winemak- ing, grower and winery relations, and stra- tegic business development. She writes a wine industry blog, which can be found at blog.vinestowine.com. phenological stage of the vine each year, sample at the same time of day in similar weather, and use the same laboratory for analysis to get as consistent and compa- rable results as possible over time. Bloom is the most common time to sample plant tissue, and the sooner the results can be analyzed and deficiencies corrected through fertilization, the better. It may also make sense to check blocks that were deficient at bloom again at veraison to see if the applications corrected the deficiencies, or if REMI COHEN