18 THE COXTROL OF COTTOX WILT AND ROOT-KNOT. 



at the time of ginning. The best way is to comb out the lint on a few 

 seeds with a very fine comb and measure with a ruler. Selections 

 having a staple less than three-fourths to seven-eighths of an inch 

 should not be saved. 



Lint index. — "Lint index" is a term used to designate the quantity 

 of lint on 100 seeds and is held by some ^ to be a more accurate 

 method of estimating the value of a strain of cotton than the lint 

 percentage. It is obtained b}" multiplying the weight of 100 seeds 

 by the percentage of lint previously determined and dividing by the 

 percentage of seed, viz, 100 minus the percentage of lint. 



Size of seed. — If the size of seed of different selections is desired for 

 comparison, the weight in grams of 100 seeds is determined. These 

 data are necessary if the lint index is to be calculated. 



Increase plats. — AMien the progeny rows that were saved have been 

 weighed, ginned, and the lint percentage determined, the one or more 

 that are to be used for the increase plats the next season for the pro- 

 duction of planting seed should be selected, choosing the ones that 

 have the greatest wilt resistance, the largest yield per hundred plants, 

 and the liighest lint percentage. These seeds should be planted on 

 wilt-infected land in the same field with the smaller plats. (See figs. 

 10, 11, and 12.) If the quantit}' of seed is small it inay be made to 

 go farther by careful hand planting. Enough seed should be reserved 

 with wliich to replant if necessary, and under no circumstances should 

 seed of another variety be used for replanting. Any missing hills 

 may well be planted to cowpeas for seed purposes. The field should 

 be tliinned, so as to allow plenty of space for the proper development 

 of each plant. During the season the field should be gone over 

 several times and all wilted or nontypical plants pulled out. Tliis is 

 extremely important, as only by removing the inferior plants can 

 crossing with them be prevented and deterioration of the cotton 

 thereby avoided. The cotton should be carefully })icked by itself 

 and every precaution taken to prevent mixing with any other cotton. 



For ginning it is best to wait until late in the season, wlien the rush is 

 over. It is tlien possible to have the work done more carefully, as 

 more time is available. If possible, a farmer wlio runs a single gin 

 should do the ginning. The roll should be taken out of the gin and 

 every seed of other cotton removed from any place where it is liable 

 to become mixed with that to be ginned. If taken to a public gin 

 the cotton should not be run through the cotton feeding device or the 

 seed througli tlie screw seed ejector. The gin should be fed by hand 

 and the seed caught pn the floor or on a piece of burlap spread down 

 for the purpose. 



1 Cook, O. r. Danger in Judging Cotton \'ariotios liy Lint Percentages. Circular 11, Bureau of Plant 

 Industry. 190S. 



[Cir. 91'] 



