28 BULLETIN 875, U. S. DEPARTMENT OF AGRICULTURE. 



pounds. In these cases the infestation was heavy enough to justify 

 the treatment, and, furthermore, the soil was generally of a decidedly 

 fertile nature. In reality these figures are quite conservative, as they 

 are based on very small plat tests where there was undoubtedly con- 

 siderable reduction in gain due to the effect of weevil migration from 

 nonpoisoned cotton. This is shown by the general results of a con- 

 siderable number of the large-scale tests conducted under conditions 

 more or less the same. Unfortunately in • large-scale tests accurate 

 figures can not be secured on the increase of yields, but it is 

 obvious from the approximate comparisons made that the gains were 

 very large, being, in fact, considerably larger than those obtained 

 in plat tests under the same conditions. Consequently it seems safe 

 to assume that with fertile soil and a fairly severe weevil infestation 

 average gains of 500 pounds or more of seed cotton uer acre are not 

 at all remarkable. 



ADVISABILITY OF POISONING UNDER PRESENT CONDITIONS. 



The first thing which must be decided by any one contemplating 

 poisoning is whether or not his conditions are such as will enable 

 the operation to be profitable. In case of doubt it would be best for 

 him to forego poisoning. As has been shown, weevil infestation 

 must necessarily be at least fairly severe. Furthermore, the soil fer- 

 tility must be such that the plants can take advantage of the protec- 

 tion afforded them by poisoning and produce a considerable gain in 

 yield. It is difficult to establish any fixed limits with regard to soil 

 productivity, but for the present at least it hardly seems advisable 

 to attempt poisoning unless the land would make at least half a bale 

 of cotton per acre in case there were no weevils. In fact, if the 

 higher-priced machinery, such as has been mentioned, is utilized, it 

 will probably be advisable to raise this limit somewhat and poison 

 onl} T land capable of making two-thirds or three-fourths of a bale 

 of cotton. This naturally means that a very large proportion of the 

 hill-land cotton will not justify poisoning at present, as the soil 

 fertility is too low. Nearly all hill farmers, however, have at least 

 a few acres of fertile bottom land in their farms which can be utilized 

 for small-scale poisoning work during the first year or two to afford 

 experience in poisoning which will make it safer for them to expand 

 the work later over the remainder of their crop. In fact, regardless 

 of conditions, unless a man is thoroughly sure of being able to con- 

 duct the operation just as outlined, it is undoubtedly best for him to 

 undertake it first on only a portion of his cotton, selecting for this 

 purpose the most fertile soil which is subject to the heaviest weevil 

 injury. 



