POTATO DISEASES IX HAWAII. 11 
Hawaii for the prevention of the late blight disease have been very 
encouraging. The fact that late blight is present upon almost every 
potato crop grown, and that when it is too dry for this disease the 
early blight is serious, should be sufficient argument in favor of uni- 
versal spraying of potatoes with Bordeaux. 
Standard Bordeaux mixture is made up according to the following 
formula, which is often referred to as 1 : 1 : 10 or 5 : 5 : 50 Bordeaux. 
Bluestone (copper sulphate) pound— 1 
Quicklime (not air slaked) do — 1 
Water to make gallons__ 10 
The mixture is prepared by dissolving the bluestone by hanging it, 
preferably overnight, in a sack immersed, the top just under the sur- 
face, in a gallon of water in a wooden container. If time is a factor, 
pulverize the bluestone and dissolve it in a gallon of hot water. 
Dilute to 5 gallons Make a lime paste by slaking the pound of lime 
in a small quantity of water, adding enough water to prevent its boil- 
ing dry. When the boiling ceases, stir to a smooth cream and add 
water to make 5 gallons. Just before the Bordeaux mixture is re- 
quired for use, pour the 5 gallons of diluted bluestone and 5 gallons 
of diluted lime at the same time into a wooden container and stir 
vigorously. Stir and strain into the spray tank and agitate occa- 
sionally while spraying, as even properly made Bordeaux settles 
gradually. The bluestone solution and the lime solution can be kept, 
but Bordeaux mixture should be used the day it is made. However, 
if sugar is stirred in at the rate of ^ pound to 10 gallons the day 
the mixture is made, Bordeaux may be kept several days in covered 
wood containers. 
Where considerable spraying is to be done, it is advantageous to 
prepare stock solutions of the bluestone and of the lime. It is con- 
venient to prepare these solutions so that each gallon contains a 
pound of chemical. Then to make 50 gallons of Bordeaux, it is neces- 
sary only to take 5 gallons of the bluestone stock solution and dilute 
it to 25 gallons, to dilute similarly 5 gallons of the lime stock solu- 
tion, and to mix the two diluted solutions. 
It is as easy to prepare Bordeaux mixture by the right method as 
by any other, and properly made Bordeaux is much more effective 
than the mixtures of uncertain physical and chemical composition 
which result from haphazard methods. For the most effective Bor- 
deaux it i> essential that the bluestone solution and the lime suspen- 
sion be diluted before combining. When properly made and properly 
applied, Bordeaux has remarkable adhesive properties, once it be- 
comes dry on foliage. 
The active principle of Bordeaux mixture is the copper, but in 
order not to injure the foliage and to render the treatment more last- 
