New YorK AGRICULTURAL EXPERIMENT STATION. 185 
Then, if heavy rains came there would be rot. In short, spraying 
prolongs the period during which the tubers are subject to rot. 
Sometimes there may appear to be more rot on sprayed rows 
than on unsprayed ones when in reality such is not the case. This 
happens when rot sets in early on unsprayed rows so that by dig- 
ging time many of the tubers have completely decayed and dis- 
appeared; while on the sprayed rows where blight was unable to 
gain a foothold until late in the season and the rot correspondingly 
retarded, all affected tubers are still in evidence at digging time. 
For an example see Volunteer Experiment No. 3, p. 168; also 
Bulletin 264, pages I1I—I12. 
When sprayed potatoes rot badly it should not be assumed, 
- without investigation, that the spraying has been a failure. If 
any unsprayed rows have been left for comparison it will be found 
generally that they have rotted much worse so that in spite of the 
rot there may be enough more marketable potatoes on the sprayed 
rows to make the spraying a profitable operation. The Peru ex- 
periment on page 150 furnishes a good illustration. In Volunteer 
Experiment No. 50 made by C. B. Foster, Water Mill (page 173), 
there were, unfortunately, no check rows in the ten-acre field where 
the rot was so severe. Hence, it can not be determined whether the 
spraying was beneficial or otherwise; but judging from similar cases 
in which the facts are known we feel confident that the spraying 
was profitable notwithstanding the rot. 
During the past season many cases were reported in which there 
was considerable loss from rot although there had been apparently 
little or no blighting of the vines. The explanation of this is that 
shortly before digging time the weather conditions were exceptionally 
favorable to rot so that a little blight, which may have passed un- 
noticed, was sufficient to cause much trouble. There may be much 
blight and yet little rot if the weather is dry for two or three weeks 
preceding digging, but if there is much rain during this period 
heavy loss from rot may follow a light attack of blight. 
Concerning the identity of the rot which was so destructive in 
this State in 1905, we have no reason for believing that it was any 
other than the rot which follows late blight; namely, that caused by 
Phytophthora infestans. Other kinds of rot undoubtedly occurred, 
in small amount, but by far the greater part of the rot in New York 
