94 Reporr oF THE BoTANIcAL DEPARTMENT OF THB 
when the potatoes were dug, September 9, the field was entirely 
free from weeds. The soil was of the same character as that 
used in 1902 and 1903, namely, a well-drained sandy loam, con- 
‘aining some gravel. 
PREPARATION AND APPLICATION OF THE BORDEAUX MIXTURE. 
Both at Geneva and at Riverhead the bordeaux mixture used 
was approximately of the 1-to—-8 formula, the same as in the 
experiments of 1902 and 1903.8 It was applied with a knap- 
sack sprayer and very thoroughly. (See Plate I.) In the later 
sprayings, after the vines became large, the rows were gone over 
twice at each spraying, the operator going out on one side and 
back on the other. This was done to insure thoroughness and 
uniformity of application. Some difficulty was experienced in — 
spraying the rows of Series I and II without getting some of the 
spray on the unsprayed rows of Series III. This was avoided 
to a considerable extent by lifting the vines of the unsprayed 
rows out of the way; but with a side wind blowing it was impos- 
sible to prevent entirely the drifting of spray onto the unsprayed 
rows. 
In the later sprayings the bordeaux was applied at the rate of 
about 200 gallons per acre at Geneva and 120 gallons per acre 
at Riverhead. 
8At the Experiment Station at Geneva there is kept on hand a stock 
solution of copper sulphate prepared by dissolving 100 pounds of copper 
sulphate in 50 gallons of water. Thus, each gallon of stock solution con- 
tains two pounds of copper sulphate. Likewise, 50 to 100 pounds of lime 
is slaked and kept in stock solution ready for use in a large wooden vat. 
In the preparation of bordeaux mixture for spraying potatoes three gallons 
of thé stock solution of copper sulphate (containing six pounds copper sul- 
phate) is poured into a 50-gallon barrel half full of water. Into this, dilute 
milk of ‘lime from the lime vat is then poured through « strainer until the 
mixture will “stand the test.” The mixture is “tested” by dropping into 
it a few drops of a solution of yellow prussiate of potash. If more lime is 
required the “test” solution turns reddish brown as soon as it comes in 
contact with the bordeaux mixture. In such case, more milk of lime is added 
until the brown color ceases to appear when the “test” is made. When 
this stage is reached it is our custom to add yet a little more of the milk of 
lime to make sure that there is plenty. An excess of lime does no harm. 
The mixture should always be thoroughly stirred before testing. 
The bordeaux mixture used in the experiment at Riverhead is prepared 
in essentially the same way except that the stock solution of copper sulphate 
used is what is called a saturated solution. This is prepared by adding to 
water as much copper sulphate as it will dissolve. The advantages of using 
a saturated stock solution are: (1) It saves the bother of weighing; 
(2) there is no danger of the strength being increased by evaporation—it is 
always the same, namely, three pounds per gallon. 
For further details of the preparation of bordeaux mixture see Bulletin 
243, pp. 319-324. 
