11] Potato Disease and Allied Diseases 25 
After a time white tufts will grow on the slices of 
potato. Examine these and they will sometimes be 
found to consist of the conidiophores of the potato 
disease fungus, showing that the mycelium of that 
fungus is present in the tubers. Sometimes the white 
tufts are portions of saprophytes which have gained an 
entry into the tuber, and when present these often make 
it difficult to find the potato disease fungus. 
Remedial Measures. 
The life history of the fungus causing potato 
disease provides us with a sound basis for deciding 
what steps to take in order to minimize the amount 
of damage done. Moisture is one of the conditions 
favourable to the disease, and so, if possible, in choosing 
a soil in which to plant potatoes preference should be 
given to one that is well drained. Having chosen our 
soil we must then exercise some care in choosing our 
seed. The disease is carried on from one season to 
another by means of mycelium in the tubers. Prac- 
tically all the potatoes from badly diseased fields 
contain this mycelium, although on many there may 
be no outward sign of it: consequently we shall be 
helping the disease if we plant them. Seed should be 
chosen from fields with the smallest amount of disease. 
In choosing between the different varieties the 
grower has to consider the value of the crops produced. 
Those susceptible to disease are usually the high 
yielders and it is for the grower to decide which are 
the more profitable on his particular soil. In good 
potato years the amount of disease on the susceptible 
varieties is usually small and even in bad years it is 
