14 
BULLETIN 
U. S. DEPARTMENT OE AGRICULTURE. 
gave as good results as the Bordeaux sprays containing 1.25 per cent 
of copper sulphate. In fact, all of the sprays gave practically the 
same results. The only plats giving yields below 240 pounds were 
the two check plats and the one treated with copper sulphate and 
lead arsenate. The yield and blight readings were practically the 
same for the plats sprayed with the Pickering solution as for those 
sprayed with Bordeaux mixture (Plate II, fig. 1). 
In Central Maine. — Separate plats of about J acre each of Green 
Mountain and Rural New Yorker seed potatoes, in Foxcroft, Me., 
were treated with Pickering and barium-water sprays of 0.7 per cent 
copper sulphate content, and with reduced lime Bordeaux, 4-4-50, 
4-2-50, and 4-1-50, sprays. The rest of the 8-acre field was sprayed 
with a standard Bordeaux, 5-5-50. Plats sprayed with standard 
Bordeaux were placed between the experimental plats. A spray 
wagon treating six rows at a time was used. As the vines were not 
sprayed until July 15, they were double sprayed at each spraying, or 
four times altogether. The results of these tests are given hi Table 4. 
Table 4. — Effect of various sprays on late blight and yield of potatoes (Central Maine, 
1918). 
Plat 
No. 
23.... 
4.... 
5.... 
6.... 
Spray used. 
Pickering (A) 
Barium water 
Bordeaux, 4-4-50. 
Bordeaux, 4-2-50. 
Bordeaux, 4-1-50. 
B ordeaux, 5-5-50 . 
Copper 
sulphate 
in spray. 
Per cent. 
0.7 
.7 
1.0 
1.0 
1.0 
1.25 
Green Mountain. 
Blight on 
vines. 
Per cent. 
Trace. 
...do 
...do 
...do 
...do 
...do 
Yield. 
Pounds. 
331 
322 
285 
338 
381 
258 
Rural New Yorker. 
Blight on 
vines. 
Per cent. 
Trace. 
...do 
...do..... 
...do..... 
...do 
...do 
Yield. 
Pounds. 
324 
332 
285 
333 
319 
330 
Obtained from two rows, 150 feet long. 
2 A ledge of rock in this plat. 
On the whole, the blight results were uniform and very low. Early 
in August a trace of blight appeared through this and other fields, 
but the dry August practically put an end to it. The yields of Green 
Mountain tubers varied somewhat, particularly at the lower end of 
the field where plats 5 and 6 were located, but plats 1, 2, and 4 gave 
practically the same yields. The Rural New Yorker potatoes were 
grown on a more uniform portion of the field, so that they showed 
uniform results, except in plat 3, where a ledge of rock reduced the 
yield. Only traces of blight were seen on the Rural New Yorker 
vines, which are much more rangy and stand up from the ground 
higher than the Green Mountain vines, making them less liable to 
infections of late blight. 
BARIUM-WATER SPRAYS IN 1916. 
It was thought that the greater solubility of barium hydrate over 
lime might be an advantage in the preparation of a spray like the 
