Sugarcane Culture

by GEORGE ARCENEAUX ALONG WITH the introduction of new sugarcane varieties, improved methods of cultivation have been developed, primarily in the time of planting and in mechanization of cultivation and weed control.

Planting sugarcane in the South has been done traditionally in late fall and early spring. Within the past two decades the average planting date has been sharply advanced. Now almost all of the planting in Louisiana is done before the old crop is harvested. Preharvest planting is also practiced in Florida and is being adopted in the sirup-producing States. This change has been due partly to the introduction of hardier varieties adapted to Temperate Zone conditions and partly to a clearer understanding of factors that affect the satisfactory overwintering of plants.

Poor stands and stunted spring growth frequently resulted from planting in September. During the initial growth, sugarcane shoots withdraw sugar from the seed piece and at a certain stage of growth reduce food reserves to critically low levels. Satisfactory overwintering of young cane plants and prompt resumption of growth in the spring depend upon large supplies of sugar in the seed pieces.

Old varieties planted in early September often gave poor stands because the young plants were killed by freezing at a stage when sugar reserves were low. But when planting is done in early August, sugar supplies in the seed piece are usually restored before winter. Food is also stored in the protected tissues of the new plant. These large reserves of food enable the young plants to make rapid growth in the spring, with increased yields of cane and a higher sugar content at harvest.

There are now available hardier new varieties that can be planted during late August and early September. By selecting the right varieties, the farmer can begin planting in early August and continue until early winter. The need for spring planting has been practically eliminated.

Mechanization, well under way before the war, was greatly stimulated by shortages of labor. Mule-drawn plows and cultivators had been largely replaced by tractor-drawn row plows and cultivators of various types. Weeding by means of hoes and other hand implements has been largely replaced by improved shaving devices, mechanical hoes, and flame cultivators.

Shaving ridge surfaces to remove winter weeds and dead growth of cane is commonly done by means of a circular blade revolving in a horizontal plane at the proper height. Recently, friction-type shavers have been extensively replaced by cutting disks that revolve at a high speed and are powered by the tractor. This improvement has greatly reduced damage to sugarcane plants.

Tractor-drawn cultivators equipped with two middle units, each made up of two shovels and a double moldboard, are now commonly used for the first cultivation. Distribution of fertilizer may be combined with this operation by' using two distributors attached to the tractor. With this equipment one man can cultivate and fertilize 35 acres a day.

Subsequent cultivation is most efficiently done by means of three-row, disk-type, tractor-drawn cultivators. Improved units can be operated by two men and will ordinarily cover 80 or more acres a day.

Flaming for control of weeds is widely practiced in Louisiana. It is based on the principle that shoots of sugarcane will be less injured by a moving flame of moderate intensity than will the weeds. It is possible, under some conditions at least, to control weeds among growing cane with relatively little injury to the crop. Thus young, succulent weeds among well-developed cane shoots can be readily killed by flaming, whereas hand-hoeing would be laborious and costly. Heat treatment is commonly applied by means of a three-row unit, using fuel oil. The cane row is double-flamed-a burner on one side of the row slightly preceding a similar one on the other side.

Recently tests with 2,4-D (2,4-dichlorophenoxyacetic acid), 1 part per 1,000, generally proved superior to flaming for control of susceptible weeds. Sugarcane plants are not injured by the concentration required for control of alligatorweed (Alternanthera philoxeroides) and other susceptible weeds. Appropriate dosages of this selective weed killer satisfactorily suppressed heavy infestations of susceptible weeds in advanced stages of growth. Under such conditions, chemical control gave larger yields of cane and sugar than either flaming or hand weeding, and resulted in a greatly reduced residual infestation of the weed.

Considerable attention has been given more economical methods of controlling weeds along ditchbanks and other waste areas that are sources of weed infestation. For years the extensive ditches, needed for drainage in Louisiana, had become increasingly infested with Johnson grass, alligatorweed, and other noxious perennials, and efforts to eradicate the weeds from the intervening cultivated areas were mostly in vain because of constant reinfestation from adjoining ditchbanks.

A recent selection, C. P. 34/120, combines good shading capacity with other desirable characteristics, and it is now being used to control weeds on ditchbanks. Best results were obtained by planting the border row as close to the ditch as possible. The increased shading prevented the establishment of bad weeds on" ditchbanks and stopped their spread to cultivated areas. A satisfactory seedbed close to the ditch can be prepared with a set of disk choppers mounted at an offset that permits operation of the tractor at a safe distance from the ditch.

The effectiveness of ditchbank-row planting of cane may be further enhanced through summer planting. Thick stands and vigorous growth ordinarily obtained with suitable varieties under such conditions usually present an effective barrier against the encroachment of weeds. The rest of the field may be planted later.

Control of weeds on ditchbanks may also be obtained by spraying with 2,4-D of appropriate concentration and by flaming. Flaming devices of the type commonly used on railroad rights-of-way are coming into extensive use for controlling Johnson grass and other weeds on waste areas. Johnson grass can be eradicated in 10 weeks or so by flaming the stem growth at specified intervals.

THE AUTHOR George Arceneaux is a native Louisianian and grew up in the heart of the sugar district. For several years he was county agent of Terrebone Parish. Since 1928 he has been in charge of sugarcane agronomic investigations of the Bureau of Plant In-dusty, Soils, and Agricultural Engineering and superintendent of the U. S. Sugar Plant Field Station at Houma, La.

Citrus at Its Best

by PAUL L. HARDING ORANGES and grapefruit have become tremendously important in the diets of Americans. I give one fact as proof, if proof were needed: Between 1933 and 1943 our production of oranges increased from 47 million boxes to 105 million and of grapefruit from 14 million boxes to 55 million. Almost as obvious as the fact that we eat a lot of citrus fruits is the fact that they are bound to vary in quality. Let us examine, as a subject worth the attention of everyone who eats or grows oranges and grapefruit, what makes them good-specifically, the relation of maturity to quality in citrus fruits.

In the early years of citrus growing in the United States the decision as to the proper time for picking the fruit was made largely by the individual grower. The increase in production resulted in more businesslike methods in handling the crop, so that eventually the industry cooperated in having State laws passed to effect more orderly marketing. Minimum standards were based on a break in the color of the rind, volume of juice, and the content of soluble solids and citric acid in the fruit, and the ratio between them.

The Department began in 1935 a comprehensive study of the factors that affect the quality of the juice of Florida oranges. Then we made similar studies of Florida grapefruit, tangerines, and Temple oranges. The results are applicable, in the strict sense, only to Florida fruit, but probably apply generally to the same varieties grown elsewhere, although we have not determined the extent to which they may thus apply in other States. The investigations included observations and measurements of physical characteristics and analyses of the chemical constituents of the principal varieties at definite intervals, beginning with immature fruit and continuing until it had become fully mature and ripe.

continuing Maturity refers to a stage of development of a fruit; ripening refers to the process by which a mature fruit becomes edible when held under suitable conditions. A mature fruit has attained the degree of development in which it will ripen with acceptable eating quality. Fruits with starchy reserves, like apples and pears, may be mature at harvestime, although many late varieties do not become ripe until sometime later, when they attain fully their soft, juicy, aromatic qualities. In contrast, oranges and grapefruit owe their sweetness to natural sugars occurring as such; they contain practically no starch, and do not undergo such a marked change in composition as apples and pears after being picked.

Since the ripening processes occur only while the fruits are on the tree, it can readily be understood that they should not be harvested until they are mature and therefore ripe. Instead of increasing in palatability after harvest, these fruits tend to lose quality, the rate of this loss depending on the temperature at which they are held. The higher the temperature, the more rapid the deterioration.