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Fruit orchard


Throughout the whole life of fruit plants in the orchard there is danger of injury from a variety of causes. Among the more common of these may be mentioned sunscald; winterkilling of the twigs and roots; winterkilling of the fruit buds; sleet storms; injuries from birds and live stock, from wind, rain, and frost in the growing season; mice and rabbits; and injury from label wires, insects, an diseases.

Sunscald - This is the name given to a condition of the bark of trees which is probably the result of exposure to the sun under peculiar conditions. Its effect is usually to injure the bark on the south and southwest sides of the tree which later peels off, leaving the wood exposed. This soon begins to decay and permanent injury results. It has been found that shading the trunk will prevent this injury, hence a common remedy is to cover the trunk with burlap, cornstalks, or similar material, especially during the time when not protected by leaves. The growing of branches on the south side of the tree so as to shade the trunk from the sun and the inclining of the trees toward the southwest are also effective remedies.

This injury is most liable to occur during severe droughts and in the early spring or late winter before growth has fairly begun. It is supposed to be caused by the warm sun of the middle of the day starting active life in the portion of the trunk exposed to its direct rays. Later, when a cold spell comes, the soluble compounds formed by the renewal of active life are decomposed and the protoplasm is destroyed.

The trees most liable to this injury are those that are newly set and weak; such as have smooth bark, as hard maple and basswood; also trees with trunks inclining to the northeast and those on dry land. It is well known that one portion of a dormant plant may start into growth independently of the condition of the rest of the plant. Thus a branch from a grapevine or other plant brought through an opening into a greenhouse in winter will soon start into growth while the rest of the vine out of doors is frozen. In like manner the portion of the trunk of an apple tree that is exposed to the direct rays of midday sun may start into growth independently of the rest of the tree.

Winterkilling - This may be confined to the twigs and flower buds of fruit trees. Injury from this cause is most liable to occur in valleys. On the adjacent higher land there may be comparative immunity. Frosts are most likely to do injury in places where the air is stagnant, especially in low spots where the air is not affected by light winds and into which the cold air from the surrounding elevations drains. Such places are indicated when the first severe autumn frosts occur, particularly if the night be calm. The dense cold air flowing into the lowlands fills the hollows and cools vegetation to the temperature of frost. In such places winterkilling is frequently serious. A windbreak may also make a frost pocket even on a side hill by interfering with the free circulation of air.

In districts where injurious frosts occur, high elevations tipping to the north or east where vegetation is rather backward, in the spring afford the best locations for fruit growing. Other locations comparatively exempt from injurious frosts are such as are near lakes or large streams, which tend to produce an equable climate.

Effect of Frost on Fruit Crops - The fruit grower, from time immemorial, has been by the mercy of the elements. Frost is millions of the most formidable foes with which he has to contend. Millions of dollars are lost annually by silent, relentless frosts that come either when the trees are in blossom or just after the fruit has set. Recent demonstrations in the fruit district of the Middle West have proved beyond a peradventure that damage to fruit trees by frost can be controlled to a greater or less extent. One of the fundamental principles that underlie successful frost fighting is a knowledge of the subject of air drainage.Cold air, like water, settles to the lowest ground, and anything that will break up this stratum of cold air and cause it to mix with the upper strata of warm air will prove of great value in combating frost injury.

Frost injury to fruit trees most frequently occurs when there is a clear, still, dry atmosphere, and when the radiation is uninterrupted by clouds or moisture, and the cold air settles in poorly air-drained areas.

While frosts may not be severe, they are often just severe enough to damage the blossoms and tender fruits, and they not only reduce a crop of fruit one-third to one-half of what it should be, but sometimes destroy the entire crop for one year or for several successive years.

Winter Injury to Twigs and Trunks in the orchard - This is commonly due to the use of varieties too tender for the locality. The most successful remedy is to secure hardier sorts. When this is not possible, or the varieties grown may be particularly profitable, the trunk is protected in winter. In northern regions the best authorities recommend that the trunks of young apple trees be surrounded with a box few inches square reaching to the branches and filled with soil to furnish protection against winter injury. They have discovered that even if the smaller branches are seriously injured by the winter, they stand a good chance of recovering, provided the trunk is uninjured.

This protection also prevents sunscald, injuries from mice and from cultivation. In Florida some orange growers protect their tree trunks by piling the soil about them as far up as the branches.

Injury to the Buds of Fruit Trees - This is a common source of loss to growers of cherries and peaches. The fruit buds of these trees are liable to start slightly in warm winter days, and to be killed by the following low temperature, although the leaf buds may not be injured. Various remedies have been prescribed for this, among the most successful where the trees are small, bending them over in autumn and covering with cornstalks. The tops sometimes are tied together and covered with cornstalks or matting. Experiments have also been made in covering the trees with various paint compounds for the purpose of giving an extra covering to the buds, but without good results.

One of the most ingenious ways of fruit protection to peach buds has been tried by Professor Whitten, who applied the principle that dark colors absorb more heat than light ones. He discovered that light-colored peach twigs were slower starting into growth than those that are dark, and conceived the idea of spraying peach trees with lime wash. He claimed to have been very successful in this practice.