18 



BULLETIN 188, U. S. DEPARTMENT OP AGEICULTUEE. 



was the same as in the other experiments, so that the average distance 

 between the plants before thinning was sHghtly over 2 inches. Owing 

 to the smaUness of the area the yields were not measured, and as 

 there were only two rows in each plat in the center of the field it is 

 probable that the behavior of the plants in this test was influenced 

 to some extent by adjoining rows. Table IX gives the total number 

 of plants considered and the average number of mature heads and 

 branches per plant. 



Table IX. 



-Heads and branches ofmilo plants, showing the effect of thinning at various 

 dates at the San Antonio Experiment Farm in 1914. 





Number of 

 plants. 



Number per plant. 



Date thinned. 



Mature 

 heads. 



Branches. 



May 12 



58 

 84 

 73 

 70 



1.26 

 1.19 

 1.13 

 1.03 



0.43 



May 25 



.23 



June 2 



1 00 



June 9 



1.30 







While the difference between the first and last thinning is not 

 great, there is a fairly consistent variation. There is a gradual 

 decrease in the number of mature heads from the first to the last 

 thinning date, but the reverse is the case with the number of branches, 

 as they increase as the date of thinning is delayed. This is to be 

 expected, for, as has been shown in previous tables, the 12-inch 

 spacing between plants is so wide that they will send out either 

 tillers or branches to offset it. Where thinning is delayed long 

 enough to allow the plants to become of sufficient size to largely pre- 

 vent tillering, as was the case with the June thinnings, branches \vill 

 be produced if the conditions during the later part of the season are 

 sufficiently favorable. 



While, as already intimated, too much importance should not be 

 given to the data in this table, the results are in accord with the pre- 

 vious experience of the writer and indicate that the time of tlunning 

 is not of great importance if it is done early enough to avoid injury to 

 the adjoining plants. If the thinning is done when the plants are 

 very small, there may be produced a considerable number of tillers, 

 a very small percentage of which will not develop, owing to crowding 

 later in the season. This is shown where counts were made earlj^ in 

 the season and at ripening time (Table V, p. 10). In the field plant- 

 ings on the experiment farm during the last two years it was found 

 to be unnecessary to do much tliinning. In 1913 the time consumed 

 in thinning the field plantings was not greater than was necessary 

 to thin corn, where the plants were thinned to 2 feet apart in the 

 row. No thinning was necessary in 1914. In both years the rows 

 were 4 feet apart and about 5 pounds of seed to the acre were jjlanted. 



