FIELD EXPERIMENTS IN 1914. 51 



It is, planned to repeat this experiment in 191 5, at which time 

 there will be added another plot in which all of the fertilizer 

 wiR be applied broadcast before planting and none applied with 

 the planter. 



The Effect of Spraying Iron Sulphate on Potato Tops. 



For a number of years the Station experimented with copper 

 sulphate and iron sulphate as a means of eradicating wild 

 mustard from oats. As it was found that wild mustard could 

 be successfully controlled in this way, numerous inquiries were 

 received relative to the possibility of exterminating wild mustard 

 in potatoes. While it was expected that the application of the 

 iron sulphate would materially injure the potato vines there 

 was no experimental evidence as to what the effect would be 

 on the resulting crop. 



In 191 3 an experiment of this kind was conducted at High- 

 moor Farm in which, strange to say, there seemed to be an in- 

 creased yield where the iron sulphate was used. The results 

 were pubHshed in Bulletin 224. It was stated as a conclusion • 

 "The experience indicates that with a field of potatoes badly 

 infested with mustard spraying with sulphate of iron solution 

 may be resorted to with a reasonable expectation that the yield 

 of tubers will not be diminished. At present such a treatment 

 can only be recommended as a rather extreme measure." 



This experiment, on which the above was based, was con- 

 ducted in the central western part of the State on Highmoor 

 Farm, and in a year in which there was a particularly long 

 growing season. A similar experiment was made on Aroostook 

 Farm the present season with Green Mountain potatoes. There 

 were five plots, three of which were untreated, one of which 

 was sprayed once with sulphate of iron, and another which was 

 sprayed twice with sulphate of iron. The tops that were sprayed 

 once quite quickly rallied, and those that were sprayed twice 

 were much more checked. The yield per acre on the unsprayed 

 plot was at the rate of 138 barrels per acre. The plot sprayed 

 once yielded at the rate of iii barrels per acre, and that which 

 was sprayed twice at the rate of 100 barrels per acre. 



The results obtained in 1914 were what would naturally be 

 expected and were quite different from those obtained at High- 

 moor Farm in 191 3. This would seem to indicate, as one would 



