I wrote directly on both sides of the leaf that is closest to the the peduncle with the pollen donors initials (SRP) another mark was placed on the peduncle and a piece of drinking straw was marked with (SRP) and slid over the peduncle just before the pollination. With leaves marked, peduncle marked, and a straw over the peduncle itself that is without breaks or cuts and simply marked with a permanent marker (sharpie) I still check on my crosses daily to ensure the marks are in place and the fruit is as it should be.