ACTION OF LEAD ARSENATE ON FOLIAGE. 25 



pounds to the 100 gallons of water without injury to foliage. " a "It 

 is totally without action on plants at any strength whatever, even 

 who n applied as a sirup." 6 Perkins : c "It does no injury to the 

 foliage." Smith: "This combination has the advantage of being 

 harmless to foliage, whatever the strength in which it is applied 



* * * . Its great advantage is its harmlessness to plant life of 

 all kinds. " d "It is absolutely harmless to foliage at any strength 



* * * . It is the only effective poison of this character that 

 can be safely applied to peach foliage and on conifers." 6 Stene:' 

 "It has the great advantage over most of our insecticides that it is 

 entirely harmless to all plants in any strength." Bentley:^ "Ar- 

 senate of lead will not burn foliage." Taft and Shaw:* u * * * 

 it can be used upon the most tender foliage without injuring it, even 

 though no lime is added." Green, Selby, and Gossard:*' "* * * 

 if properly made from good materials, will burn foliage but little, no 

 matter what strength is used." 



Others who have used and experimented with it have found that 

 it frequently caused serious injury. In some of the cases reported 

 pench trees to which it was applied were practically entirely defoliated. 

 There are a number of causes to which this variation in the observa- 

 tions of different investigators may be attributed. In the first place 

 some of them are not based on experiments carried on for a sufficient 

 length of time, or they have been conducted on apple or equally 

 hardy foliage and the assumption made that the results would be 

 the same on all foliage. No doubt, also, arsenate of lead of poor 

 quality and containing an unnecessarily large amount of arsenic in 

 i\ water-soluble form has been used in some cases, which would result 

 in burning. In view of the analyses reported in Table I, page 9, 

 it would appear that this might easily occur. Making allowance for 

 all of these conditions, however, it is still evident that injury results 

 at times from the use of properly made lead arsenate, while the same 

 experiments carried out in the same way at a different time or place 

 may not result in any injury. It is well known that the effect of 

 insecticides and fungicides in general on plants shows great variation 

 in different parts of the United States, and even in the same place 

 in different years, depending upon the temperature, moisture, and 

 undetermined influences. Formulas that may be injurious to foli- 



U. S. Dept. Agr., 1898, Farmers' Bui. No. 19, p. 6. 

 b Proc. Seventh Ann. Meeting, Assn. Econ. Ent., 1897, p. 24. 

 c Seventh Ann. Rep., Vermont Agr. Exper. Sta., 1893, p. 124. 

 d Economic Entomology, 1896, p. 437. 

 eNew Jersey Agr. Exper. Sta., 1903, Bui. 169, p. 8. 

 /Rhode Island Agr. Exper. Sta., 1904, Bui. 100, p. 138. 

 Tennessee Agr. Exper. Sta. Bui., 1905, vol. 18, No. 4, p. 36. 

 h Michigan Board of Agriculture, 1908, p. 397. 

 Ohio Agr. Exper. Sta., 1908, Bui. 199, p. 94. 

 23904 Bull. 13110 4 



