This section is from "The Horticulturist, And Journal Of Rural Art And Rural Taste", by P. Barry, A. J. Downing, J. Jay Smith, Peter B. Mead, F. W. Woodward, Henry T. Williams. Also available from Amazon: Horticulturist and Journal of Rural Art and Rural Taste.
The advantages of shelter belts are,
1st. That they mitigate the extremes of heat and cold, both of which are brought mainly by western winds.
2d. That they check the rapid evaporation of moisture, and probably increase the local rainfall.
3d. That they protect the trees from the mechanical effects of winds that would otherwise bend them over and shake off the fruit.
The sum of these advantages is a large amount. It is probable that the deterioration of trees and fruits that many claim to take place as the country grows older, is the result not of a decrease of rainfall or mean temperature, but of the extremes of heat and aridity, of cold and drought that come from a more naked surface, and anything that will in any degree restore the equilibrium must be of value.
On the other hand, the disadvantages of shelter belts are,
1st. They rob the nearer orchard trees'of their sustenance and prevent their proper development.
2d. They prevent, to a certain extent, proper ventilation of the orchard, resulting in an increase of fungoid disease and a healthy development of fruit. Even movement on the stem, our grape-growers declare, is necessary for the production of the finest grapes. Many of our Southern Illinois grape-growers also think it essential to provide for proper ventilation in their vineyards by widening the spaces between the north and south rows and having no protection on the north to prevent the free passage of the south winds. The same is no doubt true to a certain extent of the orchard fruits.
The first of these disadvantages can easily be guarded against by leaving wide spaces between orchard belts and the nearer trees. The second is more difficult. It amounts to this: - That checking the free passage of air does at once good and harm, and we must, to the best of our ability, endeavor to get the good without the mischief. To do this we would suggest the following points:
1st. Plant shelter belts in this State on the west sides of your orchards only. They will thus tend to break the force of the west and the northwest winter winds. If the orchard or field is large it may be well, as Mr. Edwards, of Lamoille, suggests, to plant one or more north and south belts through the orchard, as has been done in the Industrial University experimental orchards.
2d. If the orchard is much exposed on the north it may answer to protect it with clumps of trees that will not entirely check circulation of air.
3d. If there be hollows running to the northward these should be each planted with a clump to prevent the ascent of the cold air that would at times be driven up them like the ocean waters into a bay.
4th. Leave the south and east sides open - the latter to be protected by your next neighbor's plantation, if at all, and the former because you wish to admit ail south winds and perhaps some portion of those from the southwest.