No. 4.] FIELD CROPS. 337 



abundantly demonstrated by results obtained in many places. 

 My own results have been inconclusive, for the reason that 

 where the treatment has been tried there has been practically 

 no rot in any part of the field. 



Prevention of Scab. 



The formation of scab on potatoes is due to the growth of 

 a parasitic fungus on or in the skin. This fungus comes 

 from spores or seed, and these spores are often put into the 

 ground with the seed potatoes planted. A sound crop may 

 be grown from scabby seed, because the spores on such seed 

 can be killed without lessening the vitality of the tubers. 

 No practical method is known for destroying the spores of 

 scab which are likely to be found in the soil where a scabby 

 crop has recently been grown. Safety from contagion from 

 this source can be secured only by rotation of crops. If 

 the crop upon any field has been scabby, it is not best to 

 plant that field with potatoes again within less than four or 

 five years. 



Seed that is scabby can be rendered fit to plant by first 

 washing and then soaking about one and one-half hours in a 

 solution of corrosive sublimate in water, in the proportion 

 of two and one-fourth ounces to fifteen gallons of water. It 

 is best to dissolve the sublimate first in a small quantity of 

 hot water. It should be remembered that the corrosive sub- 

 limate is a dangerous poison if taken internally. Wooden 

 vessels should be used to hold the solution, as it will corrode 

 metals. 



The potatoes after soaking are taken out, spread to dry, 

 and should then be at once cut and planted. Do not cut 

 before the treatment. The same solution can be repeatedly 

 used, but should be thrown where no animals can reach it, 

 after all the seed has been treated. 



This method is fully described in Bulletin No. 9 of the 

 North Dakota Experiment Station, by its discoverer, Pro- 

 fessor Bolley. 



Harvesting and Storing. 



The potato digger has now been brought to such a degree 

 of perfection that its use in large fields is an essential to 

 economy. One of the best machines is " Hoover's," costing 



