20 The Colorado Experiment Station. 
since the germs are inside of the plant, as well as in the soil, and 
so far as our present knowledge goes, there is no practical method 
of sterilizing soil in the field. Prevention is the only remedy. Do 
not use diseased tubers for planting and avoil planting on potato- 
sick-land as well as on land which has had diseased tomatoes or egg 
plants. 
This disease must not be confused with the fungus blights, 
known as early and late blight, which respond quite readily to 
spraying with Bordeaux mixture. In this case, the organisms 
which cause the blight grow on the outside of the vines and can be 
easily reached and destroyed by the spraying mixture. 
The symptoms of the blight in the tomato and egg plant are 
much the same as those for the potato. The vines wilt as if suffer¬ 
ing from too hot sun or lack of water. Decay of the stems and 
branches soon sets in, resulting in the destruction of the plant. 
Here, too, spraying has been found useless, for the cause of 
the disease is deep seated within the tissue and beyond the reach of 
any germicide. Insects, undoubtedly, play some part in carrying 
the germs from plant to plant and thus spread the trouble, but the 
soil seems to be the principal medium of infection. What has been 
said in connection with the potato may be said about planting to¬ 
matoes and egg plants on land that has had diseased specimens of 
the potato family. 
If the disease is not too general, it is possible to control its 
spread by removing the dead vines with the roots from the field and 
burning them. It is of utmost importance that the vines be de¬ 
stroyed and not thrown down carelessly to start the disease in a 
healthy part of the field. Remember that you are dealing with a 
contagious disease and it is your duty to keep it from Spreading. 
One sick vine in your field this year may mean the loss of half your 
plants next year. Numerous cases have been reported where soil 
diseases have been carried from farm to farm, up and down the 
road by the infected mud that adheres to the wagon wheels. The 
greatest care should be exercised in plowing and cultivating not to 
drag sick vines over healthy soil, for by so doing the disease is 
spread, and what might have been a mild attack is aggravated to 
such a degree that a general epidemic results. Tools should be 
thoroughly cleaned before going from an infected field into one free 
from the disease and, as a further precaution, they should be disin¬ 
fected by washing or dipping them into' a 5 per cent, solution of 
either carbolic acid or copper sulphate, commonly known as blue 
stone. It is important that the gardener’s shoes, a^ well as those 
of his horse, be free from clumps of infected soil before going into 
a new field. 
There is a common practice among some farmers of hauling 
