POTATO SCAB 5 1 



These results fairly represent the value of spraying, but as 

 the depredations of the fungous diseases vary so much from 

 year to year, and with other varying conditions, more favor- 

 able as well as less favorable ones may be obtained. 



The scab of potatoes is caused by an organism which, while 

 of a vegetable nature, ditiers considerably from those causing 

 the blights. The scab of the potato has no similarity or rela- 

 tion to the above-described scab of the apple. The appearance 

 of scabby potatoes needs no description. The organisms caus- 

 ing the disease ma}- be present in the soil or upon the seed 

 used. It has been found that certain forms of fertilizers, while 

 they do not cause the disease, produce a condition of the soil 

 which is especially fivorable for its development. These fer- 

 tilizers are stable manure, ashes, and lime or plaster. 



Treatment of the scab. If possible, seed free from scab 

 should be planted, but under ordinary conditions it is difficult 

 to be certain that the seed is wholly uncontaminated. Potatoes 

 should not be planted a second time on soil which has pre- 

 viously produced a scabby crop. The use of the above- 

 mentioned fertilizers should be avoided. Seed may be freed 

 from all or most of the germs by soaking in a solution of corro- 

 sive sublimate. This treatment may be carried out in the fol- 

 lowing way : Dissolve corrosive sublimate in water at the rate 

 of one ounce to eight gallons of water. Keep this solution in 

 a wooden vessel ; a barrel, half barrel, or wash-tub will answer 

 the purpose. Put the potatoes to be treated in a coarse sack- 

 ing bag, and plunge in the solution ; let them remain for an 

 hour and a half, moving them about occasionally to insure 

 thorough wetting ; then dry the potatoes, and they are ready 

 for planting. Care should be taken that they do not become 

 contaminated again by dirt from untreated potatoes. It should 

 be remembered that corrosive sublimate is a violent poison if 

 taken internally, therefore care should be taken in using it. 



In 1S95 the following experiment was made, to ascertain the 



effect of different fertilizers on the development of the scab : 



Four plots of 4 rows each were planted. 



Plot I was fertilized with commercial fertilizer. 

 Plot 3 was fertilized with stable manure. 

 Plot 3 was fertilized with plaster. 

 Plot 4 was fertilized with wood ashes. 



