Materials Needed

A stamped paper bag is provided in the kit to hold the petioles.

Procedure

Select two leaves from each of 30 vines. The leaves should be:

- from a bearing primary sheet

- the youngest mature leaves on the shoot

- well exposed to sunlight

The youngest mature leaf is the youngest leaf on the shoot to obtain the full leaf size. Remove and discard the leaf blade and keep only the petiole (the stem of the leaf). Sixty petioles constitute the sample for most varieties. Some varieties with very small petioles may require the collection of 100 petioles, especially if nitrogen analysis is to be performed. For samples collected at bloom, select the petiole opposite the basal cluster instead of the youngest mature leaf.

To remove spray residue and dust, the leaves should be removed and the petiole washed in a mild detergent solution (ordinary dish detergent may be used) for no more than 30 seconds. Then rinse in distilled water for another 20-30 seconds. Shake the excess water from the petioles and dry at room temperature until they become "crispy" dry. Washing should be done immediately after the sample is taken before any wilting occurs.

To dry the sample, spread the petioles out on a clean surface for at least 3-5 days. If the petioles are not allowed to dry sufficiently, they can mold in the bag and the sample will be of no value.

Bag up the dry petioles, seal the bag, and fill out the information on the side of the bag.

Place the bag and the information sheet in the large envelope. Before closing the envelope, be sure the petiole samples and the information sheet have the same reference number. Seal the large envelope and return it to the Cornell Cooperative Extension Office or mail it to the Finger Lakes Grape Program, 417 Liberty Street, Penn Yan, NY 14527.