Each year at this time, we normally take petiole samples from each grape variety in each vineyard and we send them to a lab for analysis.
Petiole Samples
What is a petiole? The petiole is the stem of a grape leaf. We will collect 50–100 petioles from each grape variety and will be careful to assure that we pick them at random throughout the block.
Why is the petiole important? Every grape vine collects water and nutrients in the root system and sends them to the leaves through liquid delivery structures in the roots, trunk, and canes. The leaves use sunlight, photosynthesis, and CO2 from the air plus the water and nutrients from the roots to create energy in the form of sugars that are then shared throughout the vine. This process is dependent on getting the needed amounts of nutrients in the form of Nitrogen, Phosphorous, and Potassium and several other micronutrients from the roots.
The lab will crush the petioles and analyze the juice that comes from them and will determine the amounts of N, P, K, and the micronutrients and they will point out to us what the deficiencies are. We can then add the needed nutrients via foliar sprays and get the sprays on the vines while the grapes are still developing. The information is precise enough that we can apply whatever nutrient is needed in each part of the vineyard.
We expect that this will increase harvest yields and improve the quality of the grapes.
