70 GRASSHOPPERS AND OTHER INJURIOUS INSECTS OF 1911 AND 1912. 



The results are so striking that we think the iron sulphide 

 should be experimented with next season very carefully to find out 

 whether it is as good an insecticide as these tables seem to show. 



In all about 16,500 apples were counted, 3,500 more than in 

 1911. 



Spraying Plums. 



The plum orchard on the hill of the station grounds was again 

 divided into three plots. This year the merits of iron sulphide and 

 commercial lime sulphur with three pounds of arsenate of lead were 

 tried. 



On April 12, two-thirds of this orchard was sprayed with com- 

 mercial lime sulphur, one part; water, nine parts, and applied as a 

 dormant spray, one-third of the plum orchard being left unsprayed, 

 as check. On May 20th, one-third of the same orchard was sprayed 

 with the 1-30 commercial lime sulphur compound with three pounds 

 of arsenate of lead to every fifty gallons of the mixture. One-third 

 was sprayed with self-boiled lime sulphur solution, 10-10-50, to 

 which was added iron sulphate at the rate of three pounds to every 

 fifty gallons of mixture. On June 20th, these two last sprayings 

 were repeated, the remaining one-third of the orchard being left as 

 control. 



Brown rot was particularly bad in 1912 and the results were 

 very good in spite of the fact that apparently there should have been 

 an extra spraying later in the season. In all 32,640 plums were 

 counted. 



Results. 



In the control or check plot (unsprayed) 31 per cent of the 

 plums were perfect. 23.5 per cent were marked with curculio and 

 the rest were diseased. With lime sulphur and arsenate of lead, 

 45.4 per cent were perfect ; 10 per cent were marked with curculio ; 

 rest diseased. With iron sulphide, 60 per cent were perfect ; 11.8 per 

 cent were marked by curculio ; rest diseased. 



This shows that iron sulphide is not the best insecticide for cur- 

 culio, but is an excellent fungicide for brown rot, perhaps the best 

 we have at this date. Present results indicate, however, that it is 

 nearly as good for curculio as arsenate of lead with commercial 

 lime sulphur. 



