TOP-WORKING LARGE WALNUT TREES

W. C. Reed, Vincennes, Indiana

In top-working large native walnut trees to the Persian or English walnut, the first operation is to cut the trees back severely. This should be done while the trees are dormant, preferably in February or early in March. Cut them back two feet or more above where you wish to graft, then cut again to where you want them. This will avoid splitting. Usually we cut back to where the limbs are from two to four inches in diameter. We have cut some back that were six to eight inches with good results. However, limbs this size require careful attention to avoid decay as it takes so long for them to heal over.

Scions for Grafting

Scions for grafting should be cut while perfectly dormant and packed in damp moss or sawdust, being careful not to have it too wet. Paper line the boxes and place in a cool place. Cold storage is much better. Scions cut during the winter and placed in cold storage will come out in good shape for grafting in May, or budding during July or August. Where there is danger of the wood being injured by cold weather it would be well to cut scions in November, before severe cold.

Time for Grafting

Wait until the new growth is well advanced or nearly in full leaf, which is about May 1 to 10, in this latitude.

Methods

Use either the wedge graft or the bark graft. We have had equally good results with each. If any difference it is in favor of the side or bark graft which we prefer because it does not split or mutilate the stock, there is not the chance for decay, and the wounds heal over much quicker. On limbs three to four inches in diameter put in three to four grafts.

Cut the stubs back one to two inches below where they were cut when dormant so you may have a fresh clean cut. Pare the rough bark off until you have a fairly smooth surface for three inches below where the limbs are cut off.

Side or Bark Grafting

For side or bark grafting split the bark with a sharp knife for about two inches where the graft is to be set. Cut your scions with about two buds. Slope the scion all from one side with a long slope so it will fit well to the wood or cambium layer; then trim off a little of the outer bark on the outside lower edge of the scion, just enough to expose the cambium so it will come in contact with the inner side of the bark on the tree.

Wedge Graft

If the wedge graft is used, take a long bladed knife (a corn knife will do) set it sloping on the cut off stock and make a clean cut through the bark first so it will split straight, then raise the handle of the knife and drive the blade into the wood, splitting it as deep as needed, depending on the size of the scion and insert a wooden wedge made from some hard wood. An old broom or hoe handle is good, tapering the wedge from both sides, leaving it thick in the center so it will come out easily after the graft is set by simply tapping lightly from first one side and then the other. In cutting the scion slope from each side with a long slope to fit the split in the stub. The outer edge of the scion should be somewhat thicker than the inner edge so that when the wedge is taken out it will be held firm. Be very careful to see that the cambium of the scion and tree meet on each edge of the scion. Pack all large cracks with tissue paper and wax thoroughly.

Waxing, Tying, Bagging

As soon as the grafts are set, cover the entire wound with grafting wax, being careful to cover the top of the stub well and the sides as far down as the bark is split, and the upper end of the scion. Then place a paper sack over the stub to prevent evaporation and leave this on until the scions start into growth. We do not use any tying material on large limbs because the bark is thick enough to hold the graft in place. However, on smaller trees it will be important to wrap the grafts well.

Grafting Wax

The best grafting wax we have found is composed of the following:

Four pounds resin, one pound beeswax, one-half pint linseed oil and one tablespoon of lampblack. Melt all together and apply with a paint brush, being careful not to have the wax too hot.

After Care

After new growth starts watch it closely every week or ten days and keep all suckers removed until the scion starts into growth. Wherever grafts fail to start the suckers may be left to grow for budding later.

Budding Large Trees

Cut back early the same as for grafting, cover all cuts with grafting wax, let all sprouts grow until time to bud, which is usually August 1 to September 1. Thin out the small, weaker sprouts and bud three or four of the largest ones, setting the bud four to six inches from where the sprout comes out of the stub. Use the patch bud, wrap carefully with waxed cloth, using muslin dipped in melted beeswax, the strips of cloth three-sixteenths to one-fourth inch wide. The following spring, about March 1, cut the sprouts back to about three inches above the bud, remove all other sprouts when new growth starts and keep all suckers removed.

Supports

At this time you will need to put up slat supports to tie the buds to. Take slats one by two inches and twelve feet long. Nail these to the sides of the limbs so they will extend six to eight feet above. Keep buds and grafts tied up every week or ten days during the growing season.

It has been our experience that budding is preferable. However, grafting in the spring and then budding in August gives you two chances the same season.

This same method applies to the pecan and hickory as well as the walnut and if the work is carefully done you will surely be well paid for your work.