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 per 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, if 
will probably be advisable to raise this limit somewhat and poison 
only 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. 
