EXPERIMENT STATION BULLETINS. 427 



grain. Formalin should not be added to the water until ready for use. 

 The results secured will depend largely on thoroughness of application. 

 The same methods will applv in the case of barley. 



R. S. SHAW, 



Director. 

 To the Editor: 



Dear Sir: — This bulletin is not issued to the Experiment Station mail- 

 ing list. You can aid the people of your community by publishing the 

 above andi urging its use. 



R. S. S. 



POTATO SCAB— WAYS OF PREVENTION. 

 Press Bulletin No. 21. 



WHAT IT IS. 



Potato scab is a fungus growth on the skin of the potato. From this 

 fungus grow spores which live over winter in the soil and on the tubers 

 in storage. Therefore, planting scabby seed generally (but not always) 

 results in a scabbj^ crop. The soil which has produced scabby potatoes is 

 almost sure to produce a scabby crop if planted with potatoes again 

 the following season. 



KILLING THE SCAB ON THE SEED. 



When potatoes are to be planted on laud free from scab the seed 

 tubers should be disinfected to prevent the introduction of the disease by 

 means of scab spores on the seed ; but if the land is already thoroughly 

 infected this is of little use. Disinfection may be accomplished in differ- 

 ent ways — by soaking the seed in corrosive sublimate solution or in forma- 

 lin or by exposing it to formaldehyde gas. 



CORROSIVE SUBLIMATE TREATMENT. 



Make a solution containing one ounce of corrosive sublimate in seven 

 gallons of water. Soak the tubers in this for 11/2 hrs. This treatment 

 has been largely superceded by the formalin treatment which is equally 

 effective, more convenient and safer. Corrosive sublimate is very poison- 

 ous. 



FORMALIN TREATMENT. 



Into 30 gallons of water pour one pint of formalin (40 per cent, for- 

 maldehyde). Soak the uncut tubers in this solution for two hours. 

 The same solution may be used several times. Take care that the treated 

 tubers are not re-infected by coming in contact with bags or crates Avhich 

 have held scabby potatoes. It is better to make this treatment only a 

 few days before planting. Formalin is not poisonous. Treated seed not 

 needed for planting may be used for food or fed to stock with safety. 



