I 



Control Measures 207 



necessary, if these diseases are to be avoided, to inspect 

 the field one or more times during the growing season in 

 order to detect the affected hills from the appearance of 

 the vines. If only one inspection can be given, this should 

 be made at about the blossoming time, because the non- 

 parasitic and other troubles can be best detected at this 

 time. A second inspection before the vines die will often 

 reveal diseased vines that could not be seen earlier. At 

 the time of inspection all diseased hills should be marked 

 for removal before digging the others in order that they 

 may not be mixed with them. If there is a considerably 

 large percentage of them, more than 10 or 15 per cent, 

 the crop should not be used for commercial seed purposes. 

 The grower, however, may select from such a field plants 

 that are healthy for his own seed, and these should be dug 

 before the others and stored by themselves. 



Field inspection 



The grower may feel that he is unqualified to do such 

 inspection himself, but certainly he can detect poor hills, 

 and with a little instruction from an expert can learn to 

 distinguish the various diseases. If, however, individual 

 farmers growing seed potatoes for sale make their own 

 inspections, there will be a great diversity of standards, 

 hence it is more practical for one man to inspect all the 

 fields in a certain locality. Such a man should be trained 

 for the work. He may be employed by an association of 

 potato-growers or by some other organization, or he may 

 be an official inspector of the state or country employed 

 to inspect fields, and tubers after digging, for the purpose 

 of certifying them. Some such method will greatly im- 

 prove the seed stock, and the grower of such stock will 



