New York Agricultural Experiment Station. 341 



until several days after treatment but was evident in twelve days, 

 at which time the worst injured leaves had turned yellow. With 

 zinc arsenite and lime-sulphur the same type of burning was present 

 but to a less degree while in combination with glucose the injury 

 was severe. 



EFFECT ON GRAPE FOLIAGE.* 



Test No 1 . — On June 22 ten vines were sprayed with zinc arsenite 

 at the rate of six pounds of the poison to one hundred gallons of 

 water. By July 26 there was severe burning of foliage and fruit. 



Test No. 2. — On June 24 ten vines were sprayed with six pounds 

 of arsenite of zinc and two gallons of molasses in one hundred gallons 

 of water. Foliage and fruit showed severe burning by July 26. 



Test No. 8. — On July 12 one acre of grapes was sprayed, using 

 zinc arsenite two pounds, molasses two gallons and water one hun- 

 dred gallons. In two weeks injury was shown similar to that in 

 the preceding tests. 



Test No. 4- — On July 13 one acre of grapes was sprayed using 

 two pounds of zinc arsenite to one hundred gallons of bordeaux 

 mixture (formula 8-8-100). No injury resulted. 



Test No. 5. — One acre of grapes was sprayed July 15 using two 

 pounds of zinc arsenite to one hundred gallons of water. Injury 

 was apparent within a week. 



Test No. 6. — On August 16 a vine was sprayed with zinc arsenite 

 two pounds, lime one-half pound and water one hundred gallons. 

 No injury resulted. 



The weather during the period of June 22 to July 12, the dates 

 of the preliminary tests and the field experiment, was dry and hot, 

 but after July 15 there was considerable rain and cool weather; 

 so that the results noted above indicate that wet weather favors 

 injury to the foliage by this poison. From June 22 to July 14 the 

 average mean temperature was 73.1°, with a maximum of 91° but no 

 rain. From July 15 to 25 the average mean temperature was 66 

 with a maximum of 83°. Rain fell on the 15th, 18th, 21st, 24th 

 and 25th; 1.33 inches falling during this time. 



Results. — Zinc arsenite when used alone or in combination with 

 molasses caused severe burning of fruit and foliage of the grape. 

 In these tests the injury was not apparent for a period varying 

 from one to three weeks. Zinc arsenite when used in combination 

 with lime or bordeaux mixture caused no injury to the foliage. 



OTHER TESTS OF ZINC ARSENITE ON FOLIAGE. 



In a few other preliminary experiments the results are as follows: 

 A slight marginal injury occurred to the foliage of pear and plum. 

 Peach leaves were severely scorched. Zinc arsenite caused no 



* These tests were made and reported by F. Z. Hartzell, Associate Entomologist. 



