30 Potato Disease and Allied Diseases (CH. 
Bordeaux mixture, when properly made, gives a 
larger yield than dry spraying, so that it is worth the 
extra care. Dry spraying can only be applied when 
the dew is on the leaves, which is a considerable draw- 
back when large areas are grown. 
The storage of potatoes requires considerable care. 
Whenever possible they should be allowed to dry before 
they are covered in the “pits” or “clamps.” The sound 
tubers should be separated from the diseased tubers 
preferably at the time of digging. If the potatoes are 
wet and dirty so as to make this impossible a temporary 
clamp should be made; later on the healthy potatoes 
should be picked out and put into a permanent clamp 
and the diseased potatoes may be fed to stock. 
The site of the clamp should be as dry as possible. 
It should be narrow and have steep sides in order to 
let the moisture escape easily. It should be covered 
with a good straight straw or similar material to keep 
out the rain. It is a common practice to cover the 
straw with a layer of earth. In the clamp the potatoes 
heat and sweat so that moist warm conditions suitable 
to the spread of the disease are obtained if it is not 
properly ventilated. Other organisms also enter 
bruised and diseased potatoes and set up the well- 
known “wet rot.” 
For the first few weeks the clamp should not be 
covered with earth but later on this is necessary to 
keep out sharp frosts. On covering with earth spaces 
should be left at the top at frequent intervals which 
are covered with straw only. The tubers should be ex- 
amined from time to time to see if they are keeping well. 
If the potatoes are wet and dirty on lifting it is advisable 
to sprinkle them with some powder to prevent the 
