266 MINNESOTA STATE HORTICULTURAL SOCIETY.. 



sary, and for the last two, about 150 gallons each time, making in all 

 400 gallons of Bordeaux mixture. The cost of materials for the above 

 formula will be: 



6 lbs. blue vitrol (sulph, copper), @7c 42 



4 lbs. lime 01 1^ 



Cost of 44 gallons 43V^ 



From the above it would appear that the cost would not exceed 

 one cent per gallon of the mixture, but as the blue vitrol may not 

 alwaj^s be obtainable at seven cents, perhaps the cost might be a 

 trifle more. At this price, the cost of the naaterial to spraj^ one acre 

 would be about ^.00. The labor involved will depend on the way in 

 which the work is done, and for each application it may be consid- 

 ered about the same as that necessary to apply Paris green. When 

 it is necessary to spray for the potato beetle, the Paris green maybe 

 applied in the Bordeaux mixture at the rate of one pound to 100 gal- 

 lons of the mixture. 



Manner of applying Bordeaux mixture. — In a small way Bor- 

 deaux mixture maj' be applied with a brush broom or bj^ any of the 

 means used for applying Paris green and water, but when the work 

 is undertaken on a large scale, it should be put on with a force 

 pump and a spra}^ nozzle, as the spray nozzle divides the liquid 

 up into a very light spray, so that the material goes much farther 

 than if put on with a watering pot or brush broom. This can be 

 done very cheaply and convenient!}^ by rigging a barrel with a force 

 pump and ten feet of hose with a spraj^ nozzle. The barrel can be 

 easily carried through the rows in a wagon. With such an arrange- 

 ment, from two to five acres maj'- be sprayed in one day, the* amovint 

 depending on the size of the tops. A spray nozzle is very impor- 

 tant. At the experiment station, we use what is called the Nixon 

 nozzle, but there are several other kinds that are just as good. 



SUMMARY. 



(1). Late blight of potatoes is probably quite a serious source of 

 loss to the farmers of the state. 



(2). Late blight of potatoes is caused by the same fungus that brings 

 on rot. 



(3). Late blight and rot of potatoes may be prevented by the appli- 

 cation of Bordeaux mixture to the tops of the potatoes after the 

 vines are one-half grown. 



(4). It is well worth while for growers of potatoes to experiment 

 in the use of Bordeaux mixture for the prevention of blight and rot, 

 although it is not recommended to treat the whole crop with it. 



(5). The cost of material for Bordeaux mixture should not exceed 

 $4-00 per acre, and under favorable circumstances may come much 

 below this figure. 



(6). The increase in the crop from the treatment recommended maj- 

 often be as much as fifty bushels per acre, and frequentlj' much 

 more. This increase will paj^ for the expense of the operation, and. 

 as the potatoes are generally larger and smoother as the result of 

 the treatment, it is probable the work will pay well. In some sea- 

 sons, little or no results have come from the practice, but such neg- 

 ative results are very exceptional. 



