POTATO DEVELOPMENT WORK-IN WISCONSIN; J '< ; -oi 



sprouts of the potato which as a result develop into repulsive, 

 black warty growths which ruin the potato for any purpose. 

 This too is a germ disease, but no effectual method has as yet 

 been found of ridding either soil or tubers of the germs. The 

 danger from this disease is so great that the United States has 

 declared a strict quarantine against potato importations from 

 all infested countries including Great Britain, North Central 

 Europe and the Canadian island of Newfoundland. The Gov- 

 ernment should be encouraged to maintain and if need be, ex- 

 tend this precautionary measure. 



SCURF DISEASES 



These are entirely superficial or affect only the outer layers 

 of the "skin" of the potato tuber, hence are less serious than 

 the "scab" diseases. They mar the appearance of the tuber, 

 however, and the fungi which cause them may, under some cir- 

 cumstances, pass to the stem of the young plant and cause more 

 injury. Hence these diseases are objectionable especially on 

 seed that is to go south or west. There are two kinds, the 

 Hack scurf or Rhizoctonia disease, and the silver scurf. Dis- 

 infection tends to hold these in check. The use of corrosive 

 sublimate solution (1:1000; 2 hrs. immersion) has recently been 

 proved to be more effective than formalin against black scurf 

 and may be resorted to where needed. 



POTATO ROT DISEASES 



There are two types of rot occurring in Wisconsin which are 

 serious enough to deserve attention. One is the bacterial Hack 

 leg, the other the fungus late blight and rot. 



Black leg. This causes a soft rot of the base of the stem and 

 may rot the tuber. The bacteria causing this disease overwin- 

 ter on such diseased tubers. Apparently they do not persist in 

 the soil. If sound potatoes are selected for seed, and are dis- 

 infected by either method previously outlined, the disease is 

 eliminated. It is important for seed growers to keep absolutely 

 free from this trouble since the use of infected seed from the 

 North has been known to cause serious loss in the southern crop. 



Late bliglit is a fungus disease primarily of the foliage, but 

 the germs washed from the leaves into the soil cause the tubers 

 to rot. Usually there is not enough of this trouble in Wiscon- 



