SPRAYING NOTES FOR 1904-1905. 53 
the potatoes which show when dug discolored spots caused by 
the blight can be prevented from rotting, since the mycelium 
of the fungus is already in the tissue of the potato. 
Decaying potatoes from different parts of Connecticut, from 
Maine, Vermont, and New York were examined under the 
microscope, and all were found to contain the mycelium of the 
blight. ‘The rot of some of these was dry and black; of others, 
soft, light-colored, and stringy. Most authorities agree that 
_ Phytophera alone does not cause soft rot in potatoes. Fre- 
quently, however, we find bacteria working with the blight, 
that cause a rapid breaking down of the tissues of the potato 
and consequently a soft rot. 
This naturally brings up the question, When should pota- 
toes be dug if they are found to be rotting in the ground from 
late blight? The spores of late blight are supposed to be car- 
ried down to the tuber in the ground by rains or by insects. 
When they reach the tuber they send out a mycelial thread 
that enters the tuber and by developing causes the rot. It is 
a well known fact that these spores retain their vitality but a 
short time. Therefore, those potatoes that do not become in- 
fected within a short time after the vines die will not rot, and 
those that are infected will rot whether they are dug or not. 
_ Observation has shown that rot does not spread from one po- 
_tato toanotherin the ground. Weshould advise that potatoes 
that are rotting in the ground from blight be left as long asthe 
season will permit before digging. 
Observations of the conditions in the field the past two sum- 
mers have led to the conclusion that the increase in yield of 
potatoes from spraying is not all due to the control of late 
blight. Anything that reduces the leaf surface of the plants 
must tend-to reduce the yield of tubers. Flea beetles and early 
blight were both quite prevalent last season on unsprayed pota- 
toes but were not troublesome on the sprayed vines. Flea beetles 
perforate the surface of the leaves, not only reducing the leaf 
surface but giving fungous diseases a means of entrance to the 
plant. 
Bordeaux mixture is not poisonous to insects, but their dis- 
taste for it is such that most of them leave the sprayed plants 
and go to the unsprayed ones or to other vegetation. This 
was very noticeable during the summer of 1904, when the flea 
