202 



Potato Diseases 



disease in its worst form occurs in poor or badly cultivated land and 

 is favoured by the wetness of the season. These points should 

 be borne in mind in attempting to arrive at an estimate of the 

 relative importance of the canker disease from an economic stand- 

 point, and to avoid the danger of unduly exaggerating the danger of 

 canker. It is surely undesirable that the potato industry in Britain 

 should suffer more than absolutely necessary, and that other countries 

 should lose by rejecting British-grown potatoes for seed which still rank 

 amongst the finest in the world. 



Fig. 8. Wart stage of potato canker. 



Nevertheless the point of view and the attitude of investigators in 

 the United States must receive consideration. Melhus points out that 

 scabbiness is a more serious handicap in the American markets than in 

 those of European countries, and further states that " If powdery scab 

 (canker) should prove no more troublesome in the United States than it 



