COTTON IN WEEVIL-CONTROL EXPERIMENTS 23 



A SEPARATE LATE PLANTING AT SAN ANTONIO 



A separate late planting of cotton was also made at San Antonio 

 on May 12, the same date as the last of the consecutive adjacent 

 plantings and from the same stock of seed. The surface soil had 

 dried, but by using broad sweeps in front of the planter drill the seed 

 was dropped in moist earth. Germination was rapid, and a fairly 

 good stand of plants was obtained, although most of the rows had 

 a few skips due to imperfect germination. Most of the seed in these 

 skips germinated following a rain on May 30, but the seedlings were 

 weak and most of them died or remained stunted. The location of 

 this planting with relation to other fields of cotton on the experiment 

 farm is shown in Figure 1. 



CLOSE SPACING IN LATE PLANTINGS 



The tendency of late-planted cotton to produce a large "rank" 

 type of stalk under certain conditions renders it desirable to leave 

 the plants closer together in the rows, in order to suppress excessive 

 vegetative growth. Plants which grow large require a longer season 

 to mature a crop, and when the season is shortened by late planting 

 overgrown plants are an added disadvantage. 



The principle of controlling the vegetative growth of plants by 

 spacing the plants closer in the rows has been tested under a wide 

 range of conditions. Equal or greater yields have usually been 

 obtained from close-spaced plants when tested in direct comparison 

 with wide-spaced plants. A greater degree of earliness is usually 

 obtained by close spacing. In open stands with the plants averag- 

 ing from 2 to 4 inches apart in the row, larger yields have been 

 obtained without thinning. 



In order to test the effect of close spacing when cotton is planted 

 late, this experiment was planned as a comparison of plants chopped 

 to two plants in a hill with plants left unthinned in the rows. The 

 test consisted of three 4-row blocks of each spacing, the unthinned 

 blocks alternating with the blocks of thinned plants. The outside 

 blocks were protected by guard rows. 



The plant spacing used in comparison with the unthinned blocks 

 was the same as that used in the time-of-planting test, two plants 

 being left in hills with the hills 12 inches apart. Thinning was done 

 in these rows on June 15, when the plants averaged about 8 inches 

 in height and had from six to eight nodes. 



OVERWINTERED WEEVILS AVOIDED 



Although the late-planted cotton was examined at frequent inter- 

 vals for indications of weevil infestation, no trace of weevil injury 

 was found during June. 



The fact that infestation from overwintered weevils was avoided 

 in the separate late planting probably was due to hot dry weather 

 during the first part of June. During this period the plants were 

 small and had not yet formed squares, so that if weevils came in 

 they had little protection against the high temperatures and did not 

 survive to attack the squares when they had reached sufficient size 

 to enable the weevils to begin breeding. Thus, it appeared that 

 the planting of May 12 had been sufficiently late to avoid infesta- 

 tion from overwintered weevils under the conditions encountered at 

 San Antonio. 





