Wednesday, May 29, 2013

Graft placement influences scion vigor

    As I traveled around Mid-America conducting grafting schools a few weeks ago, I had the opportunity to see some common grafting errors made by some very well-intentioned pecan growers. One of the most common mistakes folks make is not cutting the stock tree back enough to force rapid growth of the scion. In the photo at right, a 3-flap graft was placed on a side limb of a young sapling. If you look at the top of this tree, the  stump visible between the two upper-most shoots was probably the location of a second 3-flap graft that ended up not taking.  In any case, the new shoot from the successful graft is only about 8 inches long--way too little growth for a new scion during first year after grafting. The upper portion of this tree should have been pruned off  as soon as the shoot on the successful graft was 2-3 inches long (at that point you are certain the graft has succeeded) . All those leaves and shoot growth above the graft  only served to slow the growth of the scion.
    When I set a graft, I prefer to cut off more of the stock right at the beginning. I know that cutting off so much of a well-tended pecan tree can cause the novice pecan grower a slight panic attack but its for the best. Cutting back the stock drastically helps to focus all the tree's root energy into growing a strong and vigorous scion.  The photo at left shows a tree I grafted about 18 inches off the ground. At  this height,  the stock tree was about 1 1/4 inches in diameter and I used a bark graft to place the scion on the stock. Once the buds on the scion had grown out about 3 inches, I selected the strongest new shoot to become my new central leader  and pruned off all the competing scion buds.  This photo was taken in mid-July and I had over 3 feet of new growth that could be easily trained to a bamboo stake.