14 MAINE AGRICULTURAL LXPLRIMENT STATION. I9I4. 



far as scab is concerned the fungicides commonly employed 

 in spraying apple trees, when used with arsenate of lead, have 

 been receiving in some instances much more credit than they 

 rcpilly deserve. 



However it should be mentioned that this is by no means 

 the first time that the fungicidal effect of arsenate of lead has 

 been observed. Waite* called' attention to the fact in 1910, 

 but stated that while this insecticide when used alone possessed 

 considerable fungicidal value it was probably not enough to be 

 depended upon for general use. In his experiments, however, 

 only 2 pounds of paste were used to 50 gallons of water. Wal- 

 lace, Biodgett and Ilessler t in both field and laboratory tests 

 also showed that the addition of arsenate of lead to lime- 

 sulphur solution increased the fungicidal value of the spray. 

 Taylor t secured somewhat similar results in Alissouri in the 

 control of peach scab and brown rot but in the case of the 

 latter disease it was thought that the effects were indirect and 

 were the result of control of the curculio' which punctures the 

 skin and thus assists the fungus in gaining entrance to the fruit. 



In our own experiments plots were sprayed with 2 and 4 

 pounds of arsenate of lead paste in 50 gallons of water in 19 12. 

 In 1913 the powdered form of the insecticide was substituted, 

 this being used at the rate of i and 2 pounds in 50 gallons of 

 water. The 1912 experiment was begun in the writer's absence 

 and, unfortunately, no unsprayed check was saved. However 

 the results obtained were quite striking. Where the larger 

 amount of arsenate O'f lead paste was used alone scab was 

 controlled as well as on any plot sprayed with the recognized 

 fungicides, exceeding that obtained with bordeaux mixture 

 and standard dilution lime-sulphur and only being equalled by 

 ibe stronger lime-sulphur. 



With the above results in mind the figures obtained in 19 13 

 possess added significance. A'Vhere the 2 pounds of dry arsenate 



* Waite, M. B., Experiments on the Apple with Some New or Little- 

 Known Fungicides Cir. U. S. D. A. Bur. PI. Ind. 58, 1910. 



t Wallace, E., Biodgett, F. M. and Hessler, L. R. Studies of the Fungi- 

 cidal Value of Lime-Sulphur. Bui. Cornell Agr. Exp. Sta. 290, 191 1. 



t Taylor, E. P., Spraying Peaches for Brown Rot, Western Fruit 

 Grower, pp. 20-21, Oct. 1909, pp. 16-18, Feb. 1910. 



