POTATO ROT. l6l 



sprayed with Bordeaux, or an increase of 17 per cent, in favor 

 of Bordeaux mixture over fungiroid. 



The last column gives the per cent, of decayed tubers. The 

 rows sprayed with Bordeaux mixture produced only .4 of 1 per 

 cent, by weight of decayed tubers, while from the unsprayed 

 rows over 10 per cent, by weight of the tubers was decayed. 

 The fungiroid seemed to have but little effect in preventing the 

 decay. 



The results do not promise the future for the fungiroid which 

 had been hoped for it, yet we do not wish to draw final conclus- 

 ions from this one season's trial. 



In spraying potatoes for the prevention of the "blight," the 

 first application should be made sometime from the first to the 

 middle of July and subsequent applications should be made at 

 intervals of from ten days to three weeks, depending upon the 

 weather, rainy weather requiring more frequent applications 

 than dry. 



If potato bugs are numerous, Paris green may be added to the 

 Bordeaux mixture at the rate of 1 lb. to 150 gallons of the 

 mixture. 



The directions for preparing Bordeaux mixture given in the 

 annual report of the Maine Experiment Station for 1889, may be 

 varied somewhat. The following formula is the one most com- 

 monly used: 6 lbs. copper sulphate, 4 lbs. fresh unslaked 

 lime, 45 gallons water. Dissolve the copper sulphate in a small 

 quantity of water; slake the lime, adding a few quarts of water 

 after the lime is slaked, and when cool mix with the copper sul- 

 phate solution and dilute with enough water to make in all 45 

 gallons. It is advisable to strain the lime solution before adding 

 to the copper sulphate, as it usually contains more or less 

 coarse material which would clog the spraying apparatus. 



The copper sulphate should not be dissolved, nor should the 

 Bordeaux mixture be prepared, in an iron vessel, as the copper 

 compound will act upon the iron. 



RECAPITULATION. 



Potato rot, late blight or rust, as the disease is variously called, 

 is the result of a fungous parasite; this disease can be held in 

 check if not entirely prevented by the use of fungicides of which 



