What should I sample?

• Collect a representative sample of 60 to 80 leaf petioles (more for small-sized petiole, less for large-sized petioles); one or two petioles per vine for each variety. A petiole is the stem that attaches the leaf blade to the shoot.
• Take petioles from mature, fully expanded leaves located 5 to 7 leaves from the shoot tip.
• Detach each petiole from the leaf blade immediately.
• Place petioles in a paper bag not a plastic Ziploc bag.
• Label each sample and keep your own record of the following:
• varieties sampled
• vineyard block where the samples are collected
• sampling date
• conditions of vineyard
• Prior to shipping, allow samples to dry for a day in a warm, dry, well-ventilated place.