Coal Tar and Asphaltum on Trees.

What is the effect of coal tar or asphaltum applied to the bark of trees?

The application of coal tar to prevent the root borers of the prune which operate near the surface of the ground was found to be not injurious to the trees, although there was great apprehension that there would be.  The application of asphaltum, what is known as “grade D,” has been also used to some extent in the Santa Clara valley without injury.  Of course, in the use of any black material, you increase the danger of sunburn, if applied to bark which is reached by the sun’s rays.

Whitewashing Fruit Trees.

When is the proper time to whitewash walnut trees to prevent sun scald? 
How high up is it advisable to apply the wash?

Whitewash after heavy rains are over and before the sun gets very hot; near the coast see that it is on early in April; in the interior it should be in place in March.  Do not wait until all the rains are over, because there is a great chance of bark-burning between rains in the spring.  Whitewash the trunk and the larger limbs — wherever the sun can reach the bark; being careful to keep the surface white where the 2 o’clock sun hits it.  Be particular to whitewash, or otherwise protect by “protectors” or burlap wrappings, all young trees; the young tree is more apt to be hurt than an old one, but bark seems never to get too old to burn if the sun is hot enough.

Shaping a Young Tree.

In shortening back long, slim limbs the side shoots come out, and one soon has a lot of ugly, crooked limbs to look at.  There are a number of orchards here being spoiled in that way.  How is this avoided?

You cannot secure a low-heading, well-shaped tree without cutting back the branches.  Afterward you can improve the form by selecting shoots which are going in directions which you prefer, or you can cut back the shoots afterward to a bud which will start in the direction which you desire.  In this way the progressive shaping of the tree must be pursued.  If you only have a few trees and can afford the time, you can, of course, bend and tie the branches as they grow, so that they will take directions which seem to you better, but this is not practicable in orcharding on a commercial scale.  There is no disadvantage in crooked branches in a fruit tree, but they should crook in desirable directions, and that is where the art in pruning comes in.

Pruning Times.

What is the best time to prune the French prune and most other trees?  In Santa Clara volley they prune as soon as leaves are off; in the mountains they prune later, say in February and March, and finish after bloom is started and of course when sap is up.  Which is right?

You can prune French prunes and other deciduous trees at any time during the winter that is most convenient to you.  It does not make any particular difference to the tree, nor does it injure the tree at all if you should continue pruning after the bloom has started.  In fact, it is better to make large cuts late in the winter, because they heal over more readily at the beginning of the growing period than at the beginning of the resting season.  It is believed that early pruning may cause the tree or vine to start growth somewhat sooner and this may be undesirable in very frosty places.