This week, I came across an article that was just posted by the Michigan State University Extension.
It is a very good article that breaks down the nutritional recommendations for grapes from petioles. This time of year is the best time to perform foliar testing because most vineyards will soon be at the period of veraison, “onset of ripening” . As the article states, it is good to always be aware of the nutrients in both the vine and the soil and to see if the soil nutrients are making it up into the plant.
The following video, mentioned in this article does a great job of explaining how to acquire a representative sample for analysis.
Another great resource is the following document, Petiole Analysis as a Guide to Grape Vineyard Fertilization from the University of Minnesota Extension.
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