I^EW YOEK AGRICULTURAL EXPERIMENT STATION. 331 



for use on foliage; and to ascertain its relative adhesive qualities 

 under ordinary weather conditions. 



PREVIOUS REPORTS ON ZINC ARSENITE. 



Luther 1 states that in the Pajaro Valley, California, zinc arsenite 

 can be used with safety on the foliage of apple, potato and bean, 

 but not on peach. Wood worth 2 in speaking of spraying operations 

 in the same region says that " this [zinc arsenite] has proven to 

 be the safest of the arsenicals that can be procured in the form of 

 a dry powder " and that " there is no doubt that the zinc arsenite 

 stands foremost at the present time among the available arsenicals 

 with high arsenic content." Swingle and Morris 3 in a study of 

 bark injury to fruit trees caused by arsenicals state that " zinc 

 arsenite (ortho) gave practically no injury under the most severe 

 conditions of the tests . . . ". Cooley 4 reports its successful 

 use against the potato beetle (Leptinotarsa decemlineata Say), the 

 larva of the European cabbage butterfly (Pieris rapce L.) and the 

 diamond-back moth (Plutella maculipennis Curt.), without injury 

 to the foliage of potato or cabbage. Johnston 5 reports favorable 

 results in a potato-spraying experiment carried on in cooperation 

 with the Virginia Truck Experiment Station. In marked contrast 

 to the above accounts is the report of Britton 6 to the effect that two 

 sprayings at an interval of seven days using three-fourths of a pound 

 of ortho zinc arsenite to fifty gallons of water were followed by 

 severe injury to apple, which caused about one-half of the leaves 

 to drop. Volck 7 recommends the substitution of zinc arsenite for 

 arsenate of lead in the first two sprayings for the codling moth and 

 he further states that " zinc arsenite . . . may cause foliage 

 injury if not properly handled. When mixed with iron sulphide 

 the foliage-injuring properties are largely restrained, and several 

 applications may be made [to apple]. When no iron sulphide is 

 used only the first (full bloom) spraying should be applied with this 

 arsenical." Gillette 8 says that during 1911 zinc arsenite was used 

 by a number of fruit growers on the western slope and no damage 

 resulted except from a single lot of the poison. He suggests that 

 the zinc arsenite manufactured is perhaps not of uniform quality. 

 Melander 9 says that in his tests zinc arsenite has not caused injury 

 to the foliage of apple. 



1 Belter Fruit, 5, No. 8: 65-66. 1911. 



2 Better Fruit, 5, No. 8: 70. 1911. 



3 Phytopathology, 1: 93. 1911. 

 *Jour. Econ. Ent., 5: 142-6. 1912. 



6 U. S. Dept. Agr. Ent. Bui. 109, pp. 53-65. 1912. 



6 Conn. State Exp. Sta. Ann. Rept. 1911, p. 358. 



7 Better Fruit, 6, No. 11 : 46-47. 1912. 



8 Letter of June 19, 1912. 



8 Better Fruit, 6, No. 12: 13. 1912. 



