Part 6
With the consideration of cotton seed oil and meal we have not, however, exhausted its possibilities. Cotton seed hulls constitute about half the weight of the ginned seed. After the seed of Upland cotton has been passed through a fine gin, which takes off the short lint or linters left upon it by the farmer, it is passed through what is called a sheller, consisting of a revolving cylinder, armed with numerous knives, which cut the seed in two and force the kernels or meats from the shells. The shells and kernels are then separated in a winnowing machine. This removal of the shell makes a great difference in the oilcake, as the decorticated cake is more nutritious than the undecorticated. For a long time these shells or hulls, as they are called, were burned at oil mills for fuel, 2-1/2 tons being held equal to a cord of wood, and 4-1/3 tons to a ton of coal. The hulls thus burned produced an ash containing an average of 9% of phosphoric acid and 24% of potash--a very valuable fertilizer in itself, and one eagerly sought by growers of tobacco and vegetables. It was not long, however, before the stock-feeder in the South found that cotton seed hulls were an excellent substitute for hay. They are used on a very large scale in the vicinity of oil mills in southern cities like Memphis, New Orleans, Houston, and Little Rock, from 500 to 5000 cattle being often collected in a single yard for this purpose. No other feed is required, the only provision necessary being an adequate supply of water and an occasional allowance of salt. Many thousands of cattle are fattened annually in this way at remarkably low cost.
Careful attention is now given to the employment of the seed in new cotton countries, and oil expression is practised in the West Indies. Hull is the principal seat of the industry in Great Britain, and enormous quantities of Indian and Egyptian cotton seed are imported and worked up.
The following diagram, modified from one by Grimshaw, in accordance with the results obtained by the better class of modern mills, gives an interesting _resume_ of the products obtained from a ton of cotton seed:--
_Products from a Ton of Cotton Seed._
Cotton seed, 2000 pounds. +------+------------------------+------ | | | | Linters, 23 pounds. | | ------------------- | | | Meats, 1090 pounds. Hulls, 888 pounds. --------+-----------+---- +---+------+----- | | | | | Cake, 800 pounds. | | | | ---+---------------+ | | | | | | | | Meal. | Fibre. | | Bran. -----------------------------+ -----+----+ | --+-- (Feeding stuff. Fertilizer.)| | | | -----------------------------+ | | | | ----------+--------+------+------- Crude oil, 290 pounds. (High-grade paper.)|(Cattle food.) -----+-------+-------- -------------------+-------------- | | | Summer Yellow. |Soap stock. (Fuel.) | +--------+------------ +--+-------- ---+-------+-------+ |(Winter | Cotton seed | | | |yellow | stearin.) Soaps. Ashes. | +--------+----------- ------ --+--- -----+------- | | (Cattle food) | | with the meal. | Salad oil. Fertilizer. | +------------------- These together, | Summer white. a very valuable +-------+----------- manure. | | | Lard. | +-------+ | | Cottolene (with beef stearin, cooking oil). +-------------------------------------------- | | Miners' oil. +------------- | | Soap. +------
_Pests and Diseases of the Cotton Plant._
_Insect Pests._--It is common knowledge that when any plant is cultivated on a large scale various diseases and pests frequently appear. In some cases the pest was already present but of minor importance. As the supply of its favourite food plant is increased, conditions of life for the pest are improved, and it accordingly multiplies also, possibly becoming a serious hindrance to successful cultivation. At other times the pest is introduced, and under congenial conditions (and possibly in the absence of some other organism which keeps it in check in its native country) increases accordingly. Some idea of the enormous damage wrought by the collective attacks of individually small and weak animals may be gathered from the fact that a conservative estimate places the loss due to insect attacks on cotton in the United States at the astounding figure of $60,000,000 (L12,000,000) annually. Of this total no less than $40,000,000 (L8,000,000) is credited to a small beetle, the cotton boll weevil, and to two caterpillars. The best means of combating these attacks depends on a knowledge of the life-histories and habits of the pests. The following notes deal only with the practical side of the question, and as the United States produce some seven-tenths of the world's cotton crop attention is especially directed to the principal cotton pests of that country. Those of other regions are only referred to when sufficiently important to demand separate notice.
The cotton boll weevil (_Anthonomus grandis_), a small grey weevil often called the Mexican boll weevil, is the most serious pest of cotton in the United States, where the damage done by it in 1907 was estimated at about L5,000,000. It steadily increased in destructiveness during the preceding eight years. Attention was drawn to it in 1862, when it caused the abandonment of cotton cultivation about Monclova in Mexico. About 1893 it appeared in Texas, and then rapidly spread. It is easily transported from place to place in seed-cotton, and for this reason the Egyptian government in 1904 prohibited the importation of American cotton seed. Not only is the pest carried from place to place, but it also migrates, and in 1907 it crossed from Louisiana, where it first appeared in 1905, to Mississippi. That the insect is likely to prove adaptable is perhaps indicated by the fact that in 1906 it made a northward advance of about 60 m. in a season with no obvious special features favouring the pest. Its eastern progress was also rapid. "The additional territory infested during 1904 aggregates about 15,000,000 sq. m., representing approximately an area devoted to the culture of cotton of 900,000 acres" (_Year-book, U.S. Dept. Agriculture_, 1904). In 1906 the additional area invaded amounted to 1,500,000 acres (_Ibid._, 1906).
The adult weevils puncture the young flower-buds and deposit eggs; and as the grubs from the eggs develop, the bud drops. They also lay eggs later in the year in the young bolls. These do not drop, but as the grubs develop the cotton is ruined and the bolls usually become discoloured and crack, their contents being rendered useless.
No certain remedy is known for the destruction on a commercial scale of the boll weevil, but every effort has been made in the United States to check the advance of the insect, to ascertain and encourage its natural enemies, and to propagate races of cotton which resist its attacks. Special interest attaches to the investigations made by Mr O. F. Cook, of the U.S. Dept. of Agriculture, in Guatemala. The Indians in part of Guatemala raise cotton, although the boll weevil is abundant. Examination showed that although the weevil attacked the young buds these did not drop off, but that a special growth of tissue inside the bud frequently killed the grub. Also, inside the young bolls which had been pierced a similar proliferation or growth of the tissue was set up, which enveloped and killed the pest. Probably by unconscious selection of surviving plants through long ages this type has been evolved in Guatemala, and experiments have been made to develop weevil-resistant races in the United States. Mr Cook also found that the boll weevil was attacked, killed and eaten by an ant-like creature, the "kelep." Attempts have been made to introduce this into the infested area in Texas; but owing to the winter proving fatal to the "kelep" its usefulness may be restricted to tropical and subtropical regions.
The cotton boll worm (_Chloridea obsoleta_, also known as _Heliothis armiger_) is a caterpillar. The parent moth lays eggs, from which the young "worms" hatch out. They bore holes and penetrate into flower-buds and young bolls, causing them to drop. Fortunately the "worms" prefer maize to cotton, and the inter-planting at proper times of maize, to be cut down and destroyed when well infested, is a method commonly employed to keep down this pest. Paris green kills it in its young stages before it has entered the buds or bolls. The boll worm is most destructive in the south-western states, where the damage done is said to vary from 2 to 60% of the crop. Taking a low average of 4%, the annual loss due to the pest is estimated at about L2,500,000, and it occupies second place amongst the serious cotton pests of the U.S.A. The boll worm is widely spread through the tropical and temperate zones. It may occur in a country without being a pest to cotton, e.g. in India it attacks various plants but not cotton. It has not yet been reported as a cotton pest in the West Indies.
The Egyptian boll worm (_Earias insulana_) is the most important insect pest in Egypt and occurs also in other parts of Africa. Indian boll worms include the same species, and the closely related _Earias fabia_, which also occurs in Egypt.
The cotton worm (_Aletia argillacea_)--also called cotton caterpillar, cotton army worm, cotton-leaf worm--is also one stage in the life-history of a moth. It is a voracious creature, and unchecked will often totally destroy a crop. In former years the annual damage done by it in the United States was assessed at L4,000,000 to L6,000,000. Dusting with Paris green is, however, an efficient remedy _if promptly applied at the outset of the attack_. The annual damage was in 1906 reduced to L1,000,000 to L2,000,000, and this on a larger area devoted to cotton than in the case of the estimate given above. It is the most serious pest of cotton in the West Indies. The Egyptian cotton worm is _Prodenia littoralis_.
The caterpillars ("cut worms") of various species of _Agrotis_ and other moths occur in all parts of the world and attack young cotton. They can be killed by spreading about cabbage leaves, &c., poisoned with Paris green.
Locusts, green-fly, leaf-bugs, blister mites, and various other pests also damage cotton, in a similar way to that in which they injure other crops.
The "cotton stainers," various species of _Dysdercus_, are widely distributed, occurring for example in America, the West Indies, Africa, India, &c. The larvae suck the sap from the young bolls and seeds, causing shrivelling and reduction in quantity of fibre. They are called "stainers" because their excrement is yellow and stains the fibre; also if crushed during the process of ginning they give the cotton a reddish coloration. The Egyptian cotton seed bug or cotton stainer belongs to another genus, being _Oxycarenus hyalinipennis_. Other species of this genus occur on the west coast of Africa. They do considerable damage to cotton seed.
_Fungoid Diseases._--"Wilt disease," or "frenching," perhaps the most important of the fungoid disease of cotton in the United States, is due to _Neocosmospora vasinfecta_. Young plants a few inches high are usually attacked; the leaves, beginning with the lower ones, turn yellow, and afterwards become brown and drop. The plants remain very dwarf and generally unhealthy, or die. The roots also are affected, and instead of growing considerably in length, branch repeatedly and give rise to little tufts of rootlets. There is no method known of curing this disease, and all that can be done is to take every precaution to eradicate it, by pulling up and burning diseased plants, isolating the infected area by means of trenches, and avoiding growing cotton, or an allied plant such as the ochro (_Hibiscus esculentus_), in the field. Fortunately the careful work of the U.S. Department of Agriculture and of planters such as Mr E. L. Rivers of James Island, South Carolina, has resulted in the production of disease-resistant races. In one instance Mr Rivers found one healthy plant in a badly affected field. The seed was saved and gave rise to a row of plants all of which grew healthily in an infected field, whereas 95% of ordinary Sea Island cotton plants from seed from a non-infected field planted alongside as a control were killed. The resistance was well maintained in succeeding generations, and races so raised form a practical means of combating this serious disease.
In "Root rot," as the name implies, the roots are attacked, the fungus being a species of _Ozonium_, which envelops the roots in a white covering of mould or mycelium. The roots are prevented from fulfilling their function of taking up water and salts from the soil; the leaves accordingly droop, and the whole plant wilts and in bad attacks dies. It has yearly proved a more serious danger in Texas and other parts of the south-west of the United States, and the damage due to it in Texas during 1905 was estimated at about L750,000. No remedy is known for the disease, and cotton should not be planted on infected land for at least three or four years.
"Boll rot," or "Anthracnose," is a disease which may at times be sufficiently serious to destroy from 10 to 50% of the crop. The fungus which causes it (_Colletotrichum gossypii_) is closely related to one of the fungi attacking sugar-cane in various parts of the world. Small red-brown spots appear on the bolls, gradually enlarge, and develop into irregular black and grey patches. The damage may be only slight, or the entire boll may ripen prematurely and become dry and dead.
Many other diseases occur, but the above are sufficient to indicate some of the principal ones in the most important cotton countries of the world.
_Improvement of Cotton by Seed Selection._
In the cotton belt of the United States it would be possible to put a still greater acreage under this crop, but the tendency is rather towards what is known as "diversified" or mixed farming than to making cotton the sole important crop. Cotton, however, is in increasing demand, and the problem for the American cotton planter is to obtain a better yield of cotton from the same area,--by "better yield" meaning an increase not only in quantity but also in quality of lint. This ideal is before the cotton grower in all parts of the world, but practical steps are not always taken to realize it. Some of the United States planters are alert to take advantage of the application of science to industry, and in many cases even to render active assistance, and very successful results have been attained by the co-operation of the United States Department of Agriculture and planters. With the improvement of cotton the name of Mr Herbert J. Webber is prominently associated, and a full discussion of methods and results will be found in his various papers in the _Year-books_ of the U.S. Department of Agriculture. The principle on which the work is based is that plants have their individualities and tend to transmit them to their progeny. Accordingly a selection of
## particular plants to breed from, because they possess certain desirable
characteristics, is as rational as the selection of particular animals for breeding purposes in order to maintain the character of a herd of cattle or of a flock of sheep.
Inspection of a field of cotton shows that different plants vary as regards productiveness, length, and character of the lint, period of ripening, power of resistance to various pests and of withstanding drought. A simple method of increasing the yield is that practised with success by some growers in the States. Pickers are trained to recognize the best plants, "that is, those most productive, earliest in ripening, and having the largest, best formed and most numerous bolls." These pickers go carefully over the field, usually just before the second picking, and gather ripe cotton from the best plants only; this selected seed cotton is ginned separately, and the seed used for sowing the next year's crop.
A more elaborate method of selection is practised by some of the Sea Island cotton planters in the Sea Islands, famous for the quality of their cotton. A field is gone over carefully, and perhaps some 50 of the best plants selected; a second examination in the field reduces these perhaps to one half, and each plant is numbered. The cotton from each is collected and kept separately, and at the end of the season carefully examined and weighed, and a final selection is then made which reduces the number to perhaps five; the cotton from each of these plants is ginned separately and the seed preserved for sowing. The simplest possible case in which only one plant is finally selected is illustrated in the diagram.
1st. Year 2nd. Year 3rd. Year 4th. Year 5th. Year +------+ +-------+ +-------+ Select (1) --->| 500 | --->|5 Acres| --->|General| Plant |Plants| | | | Crop | +------+ +-------+ +-------+ | | \/ +-------+ +-------+ +-------+ Select Plant (1) ----->| 500 | --->|5 Acres| --->|General| | Plants| | | | Crop | +-------+ +-------+ +-------+ | | \/ +-------+ +-------+ Select Plant (1) ------>| 500 | --->|5 Acres| | Plants| | | +-------+ +-------+ | | \/ +-------+ Select Plant (1) ------>| 500 | | Plants| +-------+ | | \/ Select Plant (1)
After Webber, _Year-book, U.S. Dept. of Agriculture_, 1902.
Improvement of Cotton by Seed Selection.
From the seeds of the selected plant of the 1st year about 500 plants can be raised in the next year. One plant is selected again from these 500, and the general crop of seed is used to sow about five acres for the 3rd year, from which seed is obtained for the general crop in the 4th year. One special plant is selected each year from the 500 raised from the previous season's test plant, and in four years' time the progeny of this plant constitutes the "general crop." The practice may be modified according to the size of estate by selecting more than one plant each year, but the principle remains unaltered. This method is in actual use by growers of Sea Island cotton in America and in the islands off the coast of S. Carolina; the greatest care is taken to enhance the quality of the lint, which has been gradually improved in length, fineness and silkiness. Mr Webber, in summing up, says, "When Sea Island cotton was first introduced into the United States from the West Indies, it was a perennial plant, unsuited to the duration of the season of the latitude of the Sea Islands of S. Carolina; but, through the selection of seed from early maturing individual plants, the cotton has been rendered much earlier, until now it is thoroughly adapted to the existing conditions. The fibre has increased in length from about 1-3/4 to 2-1/2 in., and the plants have at the same time been increased in productiveness. The custom of carefully selecting the seed has grown with the industry and may be said to be inseparable from it. It is only by such careful and continuous selection that the staple of these high-bred strains can be kept up to its present superiority, and if for any reason the selection is interrupted there is a general and rapid decline in quality."
When selection is being made for several characters at the same time, and also in hybridization experiments, where it is important to have full records of the characters of individual plants and their progeny, "score cards," such as are used in judging stock, with a scale of points, are used.
The improvements desired in cotton vary to some degree in different countries, according to the present character of the plants, climatic conditions, the chief pests, special market requirements, and other circumstances. Amongst the more important desiderata are:--
1. Increased Yield.
2. Increase in Length of Lint.--Webber records the case of Stamm Egyptian cotton imported into Columbia, in which by simple selection, as outlined above, during two years plants were obtained uniformly earlier, more productive, and yielding longer and better lint.
3. Uniformity in Length of the Lint.--This is important especially in the long-stapled cottons, unevenness leading to waste in manufacture, and consequently to a lower price for the cotton.
4. Strength of Fibre.--Long-stapled cottons have been produced in the States by crossing Upland and Sea Island cotton. These hybrids produce a lint which is long and silky, but often deficient in strength: selection for strength amongst the hybrids, with due regard to length, may overcome this.
5. Season of Maturing.--Seed should be selected from early and late opening bolls, according to requirements. Earliness is especially important in countries where the season is short.
6. Adaptation to Soil and Climate.--High-class cottons often do not flourish if introduced into a new country. They are adapted to special conditions which are lacking in their new surroundings, but a few will probably do fairly well the first year, and the seeds from these probably rather better the next, and so on, so that in a few years' time a strain may be available which is equal or even superior to the original one introduced.
7. Resistance to Disease.--The method employed is to select, for seed purposes, plants which are resistant to the particular disease. Thus sometimes a field of cotton is attacked by some disease, perhaps "wilt," and a comparatively few plants are but very slightly affected. These are propagated, and there are instances as described above of very successful and commercially important results having been attained. Special interest attaches to experiments made in the United States to endeavour to raise races of cotton resistant to the boll weevil.
8. Resistance to Weather.--Strong winds and heavy rains do much damage to cotton by blowing or beating the lint out of the bolls. In some instances a slight difference in the shape, mode of opening, &c., of the boll prevents this, and accordingly seed is selected from bolls which suffer least under the particular adverse conditions.
Attention has been paid in the West Indies to seed selection, by the officers of the imperial Department of Agriculture, with the object of retaining for West Indian Sea Island cotton its place as the most valuable cotton on the British market.
In India, where conditions are much more diversified and it is more difficult to induce the native cultivator to adopt new methods, attention has also been directed during recent years to the improvement of the existing races. Efforts have been made in the same direction in Egypt, West Africa, &c.
_The World's Commercial Cotton Crop._
It is impossible to give an exact return of the total amount of cotton produced in the world, owing to the fact that in China, India and other eastern countries, in Mexico, Brazil, parts of the Russian empire, tropical Africa, &c., considerable--in some eases very large--quantities of cotton are made up locally into wearing apparel, &c., and escape all statistical record. It is estimated that the amount thus used in India exclusive of the consumption of mills is equivalent to about 400,000 bales. Neglecting, however, these quantities, which do not affect the world's market, the annual supplies of cotton are approximately as follows:--
+---------------------------+------------------+-----------+ | | Approximate | | | Country | Production. |Percentage.| | | Bales of 500 lb. | | |---------------------------+------------------+-----------+ | United States of America | 11,000,000 | 68.75 | | India | 3,000,000 | 18.75 | | Egypt | 1,000,000 | 6.25 | | All other countries | 1,000,000 | 6.25 | | +------------------+-----------+ | Total | 16,000,000 | 100.00 | +---------------------------+------------------+-----------+