The month of March sure came in like a lion. On the morning of March 4th, we recorded the coldest temperature for the 2018-2019 winter; 7 degrees F (-14 C). So when things warmed up a little this past weekend, I went out to the pecan grove to check on twig health. Since my trees have remained fully dormant all winter the cambium under the bark was still bright green (photo above). Since the trees are still dormant and the wood is still in good shape, I took advantage of some better weather to cut even more scions.
I had already cut all the scions I could reach from the ground while pruning my young trees, but this past weekend I needed to get up high into some more mature trees to collect wood from some of the trees in my pecan breeding block. Collecting wood from mature trees is usually a challenge because shoot growth is usually short and buds are close together (close buds make carving a scion more difficult).
Up in the tree, I spotted what looked like nice long shoots--perfect for scionwood (photo at left). This tree happens to be a cross between Major and Pawnee. Note that even in early March the shoot is still hanging on to a few rachii from last summer's leaves. This is a characteristic inherited from its Pawnee parent.
On closer inspection, I noted that these long shoots were actually a combination of both 2-year-old and 1-year-old growth (photo at right). Note that only the 1-year-old portion of the stem has large prominent buds. In contrast, all of the primary buds on the 2-year-old wood have aborted from the stem.
Because of healthy large buds, I usually collect only 1-year-old wood for scions but in this case, the short shoot growth found on this heavily bearing and mature pecan tree is just not well suited for grafting.
To gain a scion I can easily graft, I cut a scion that is part 1-year-old wood and part 2-year-old wood. I start by cutting the shoot off the tree at a point about 3.5 inches below the beginning of the 1-year-old wood. (photo at left). The presence of healthy buds on the lower portion of the scion is not important to graft success. This is the part of the scionwood stick that will receive all my cuts during the grafting process. For me, its important to harvest a scion that is at least 3/8 inch in diameter and contain more wood than pith inside the stick. I've found that thin, pithy scions have a high failure rate.
To complete this scion, I remove the upper portion of the 1-year-old wood. Note that I'll still have some nice plump buds to provide growing points for the graft. In the end, I only harvested a single scion from each shoot. The scions are about 7 inches long in total and are exactly one half 2-year-old wood and one half 1-year-old wood.
Although I much prefer collecting scions from young vigorously growing trees, some times you have to just make things work.
