12 THE STATUS OF THE COTTON BOLL WEEVIL IN 1909. 



the plants has been the only unportant and generally applicable 

 direct means at the command of the planter. Powdered arsenate of 

 lead is especially important as a direct means of killing weevils that 

 may be applied at a season in which hitherto no important means of 

 a direct nature have been available. Extensive work that is now 

 being planned it is hoped will lead to definite recommendations as to 

 the procedure to be followed in the use of the poison for the greatest 

 possible profit under various conditions. 



The most important difficulty that is likely to be encountered in 

 the use of powdered arsenate of lead against the boll weevil is the 

 possible deleterious effect of the poison in the soil. Recent investi- 

 gations conducted in orchards in Colorado where spraying of arsen- 

 icals has been practiced for many years seem to indicate that a con- 

 siderable amount of damage has resulted from the arsenic that has 

 become lodged in the soil near the bases of the trees. In fact, Prof. 

 W. P. Headden believes that in addition to the caustic effect of the 

 arsenic on the roots of the trees there is a probability that damage is 

 done the plants by absorption. At any rate, cases have been observed 

 where the general health of the trees seems to have been affected in 

 such a manner as would only seem likely to result from absorption. 

 Although this matter is by no means fully understood at this time, 

 it will be necessary to investigate carefully the possibility of injuri- 

 ous effects on cotton lands from repeated annual applications of 

 such large quantities of powdered arsenate of lead as were found to 

 be profitable in the experimental work in controlling the boll weevil. 

 If the cumulative effect of these applications is at all considerable, 

 the use of the poison can not be advised. At the same time there is 

 a possibility that something may be done in the counteracting of the 

 possible deleterious effects of arsenate of lead by the application of 

 some material with the fertilizers. 



Approved : 



James Wilson, 



Secretary of Agriculture. 

 Washington, D. C, April 1, 1910. 



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