One Thousand Questions in California Agriculture Answered Part 21

I am planning to plant walnuts on rather heavy soil. I have been told to put the nut six inches below the surface, but think that too deep, as soil is rather heavy.

In a heavy soil we should not plant these nuts more than three inches below the surface, but should cover the surface with a mulch of rotten straw to prevent drying out.

Pruning Grafted Walnuts.

Should English walnut trees be pruned? I have along the roadside English walnuts grafted on the California black, and they have grown to very large size and the fruit seems to be mostly on the outside of the trees.

English walnuts are not usually pruned much, though it is often desirable, and of course trees can be improved by removing undesirable branches and especially where too many branches have started from grafts, it is desirable that some be removed. They should be cleanly sawed off and the wound covered with wax or thick paint to prevent the wood from decaying.

Pruning Walnuts.

When is the best time to remove large limbs from walnut trees?

This work with walnuts or other deciduous fruit trees should be done late in the winter, about the time the buds are swelling; never mind the bleeding, it does no harm, and the healing-growth over the wound is more rapid while the sap is pus.h.i.+ng.

Grafting Walnuts.

In cleft grafting walnuts is it necessary to use scions with only a leaf bud, or with staminate or pistillate buds? Is cutting the pith of the scion or stock fatal to the tree?

In grafting walnuts it is usual to take shoots bearing wood buds, and not the spurs which carry the fruit blossoms, although a part of the graft containing also a wood bud can be used, retaining the latter.

Cutting into the pith of the scion or of the stock is not fatal, but it is avoided because it makes a split or wound which is very hard to heal.

For this reason it is better to cut at one side of the pith in the stock, and to cut the scion so that the slope is chiefly in the wood at one side of the pith and not cutting a double wedge in a way to bring the pith in the center.

Grafting Nuts on Oaks.

I have 10 to 15 acres of black oak trees which I wish to graft over to chestnuts. Can grafting be done successfully?

Some success has been secured in grafting the chestnut on the chestnut oak, but not, so far as we have heard, on the black oak. But grafts on the chestnut oak are not permanently thrifty and productive, though they have been reported as growing for some time. The same is true of English walnut grafts on some of the native oaks.

Grafting Walnut Seedlings.

Would it be proper to graft one-year California black walnut seedlings that must also be transplanted?

As the seedlings must be moved, plant in orchard and graft as two or three-year-olds, according to the size which they attain.

Pruning the Walnut.

What is the proper time for pruning the walnut? Is it bad for the tree to prune during the active season? I have recently acquired a long-neglected grove in which many large limbs will have to be removed in order to allow proper methods of cultivation to be practiced, and I am in doubt as to the wisdom of doing this during the rise of sap.

The best time to remove large limbs to secure rapid growth of bark from the sides of the cut, is just at the time the sap is rising. There will be some outflow of sap, but of no particular loss to the tree. As soon as the large wounds have dried sufficiently, the exposed surface should be painted to prevent cracking of the wood.

Eastern or California Black Walnuts?

I am told that the Eastern black walnut is a more suitable root for the low lands in California than the California black. Is this true?

There has been no demonstration that the Eastern black walnut is more suitable to low moist lands than the California black walnut. Our grandest California black walnut trees are situated on low moist lands.

Walnut Grove is on the edge of the Sacramento river with immense trees growing almost on the water's edge. Walnut Creek in Contra Costa county is also named from large walnut trees on the creek bank land. We have very few Eastern black walnut trees in California and although they do show appreciation of moist land, they are not in any respect better than the Californian.

Ripening of Walnuts.

I send you two walnuts. I am in doubt if they will mature.

The nuts are well grown, the kernel fully formed in every respect.

Whether they will attain perfect maturity must be determined by an observation of the fact and cannot be theoretically predicated. Where trees are in such an ever-growing climate as you seem to have, they must apparently take a suggestion that the time has arrived for maturity from the drying of the soil. The roots should know that it is time for them to stop working so that the foliage may yellow and the nuts mature. It is possible that stopping cultivation a little earlier in the season may be necessary to accomplish this purpose.

Cutting Below Dead Wood.

I have some seedling English walnut trees which are two years old, but they are not coming out in bud this year. They are about three feet high, and from the top down to about 10 inches of the ground the limbs are dark brown, and below that they are a nice green. I cut the top off of one of them to see what is the matter that they do not leaf out, and I found that there is a round hole right down through the center of the tree down to the green part. The hole is about three-sixteenths of an inch in diameter. The pith of the limbs has been eaten away by some kind of a worm from the inside. Would it be better to cut the tree down to the green part, or let them alone?

It is the work of a borer. Cut down to live wood and paint over the wound or wax it. Protect the pith until the bark grows over it or you will have decay inside. If buds do not start on the trunk, take a sucker from below to make a tree of. You could put a bud in the trunk, but it is not very easy to do it.