14 BULLETIN 1153, U. S. DEPARTMENT OF AGRICULTURE. 



In a 100-foot section of a row 312 plants were counted by Mr. Taylor r 

 with a total of 752 bolls, or only two or three bolls per plant, on the 

 average, but yielding at the rate of about 2,100 pounds of seed cot- 

 ton per acre. Further tests must determine whether this extreme 

 method of close spacing can be used to general advantage in Ten 

 nessee or elsewhere. But Mr. Bailey's experiment is of interest as 

 showing the range of possibilities that must be taken into account 

 to meet the requirements of different local and seasonal conditions. 

 Very high yields were obtained from a one-fourth-acre plat of 

 Pima (Egyptian) cotton grown at Sacaton, Ariz., in 1918, with the 

 rows 2-J feet apart and the plants spaced to about 4 inches: but 

 repetition of this experiment in 1920 and 1921 gave different results. 

 In 1920 there were no heavy summer rains, so that it was possible 

 to control the growth of the plants by careful irrigation, while in 

 1921 such control was not possible, owing to heavy rainfall in July 

 and August. With too much moisture and rank growth, the plants 

 became tall and spindling, and the yield was reduced to a rate of 

 1,148 pounds per acre, in comparison with 2,113 pounds in 1920 and 

 3,136 pounds in 1918. Several of the wider spacings in 1921 yielded 

 more than the very close rows; hence it would have been very un- 

 fortunate if the farmers had been advised to plant their cotton 2£ 

 feet apart because this arrangement gave the highest yield in 1918. 



LATE THINNING TO SUPPRESS VEGETATIVE BRANCHES. 



For close spacing to be practicable the vegetative branches or 

 secondary stalks should be suppressed, so that the plants have only 

 the single main stalk. Injurious crowding results if many vegeta- 

 tive branches are produced on plants that stand close together. Even 

 at 12, 15, or 18 inches apart the plants may be too crowded if there 

 are many vegetative branches, more crowded, in fact, than single- 

 stalk plants with 6-inch or 3-inch spacing. The development of 

 vegetative branches is influenced, of course, by the weather and the 

 soil conditions as well as by the spacing. With rich soil and hot 

 weather there is danger of producing too many vegetative branches 

 if the plants are thinned early and left more than 6 inches apart. 



It has been supposed that cotton should be thinned as early as 

 possible, to make the plants stocky and spreading, after the analogy 

 of trees; but such plants are more likely to produce vegetative 

 branches than to mature an early crop of bolls. Very early thin- 

 ning of cotton is often detrimental on account of greater exposure 

 of the .young seedlings to dry winds, blowing sand, and cutworms or 

 other pests, s i that the stand may be lost or seriously reduced. Very 

 late thinning is also distinctly detrimental when the plants are 

 checked and made too spindling. Fruiting branches on the lower 

 joints of the main stalk, as well as vegetative branches, may be sup- 

 pressed if the stand is thick and thinning is deferred too long. 

 Hence it is important not to thin too early or too late, but to adapt 

 the time of thinning to the needs of the particular case as deter- 

 mined by the conditions of the plants and the width of spacing to 

 be used, if that has been decided beforehand. Between the extremes 

 of early and of late thinning an exercise of practical judgment is 

 possible if the factors of the spacing problem are clearly understood. 



