No I just take the Brix from the grapes. Not sure about testing leaves, I’ll have to research. Typically I send samples to get analyzed about 2-3 Brix lower than my goal. Then send another sample at harvest to see how the grapes will be during the initial fermentation stages. This helps me determine how to adjust the ph and tartaric acid levels and how to adjust the wine to have a strong and balanced fermentation which leads to a sound wine.
Discussion
I ask about the sap brix because (and this goes for almost all plants) if the plant sap brix is very high, insects don't want to munch on the leaves as it's indigestible to them.
A sap analysis will tell you what nutrients (macro and micro) the plant is actually uptaking.
Lets say a soil test says you have plenty of phosphorus. The sap test on that plant doesn't show enough phosphorus. That means the phosphorus in your soil is mostly unavailable for plant uptake.
John Kempf turned me on to sap brix and plant sap analysis (https://advancingecoag.com/plant-sap-analysis/).
He has a great podcast (https://advancingecoag.com/podcasts/) I highly recommend this podcast considering you have a vinyard.
David! That’s fucking awesome! I will definitely check it out. Thanks for the recommendation.🤯
Happy to be of service, Tommy.
Nice. Cool climate here takes are of the bugs for me