350 GARDEN FARMING 



that have previously held scabby potatoes. The treatment should also be made 

 before the potatoes are cut for seed. 



The expense connected with the treatment of seed potatoes by the gas 

 method will vary in different cases according to the amount of labor required 

 in handling and whether a special building has to be erected for the purpose. 

 The cost of labor and of the building will be the principal items. The cost of 

 the materials need not amount to over i cent per sack. For example, a shed 

 12 by 24 feet and 7 feet high contains 2016 cubic feet and would require 

 3 pounds of potassium permanganate, costing 60 cents, and 6 pints of formalde- 

 hyde, costing $1.20 ; total $1.80. Two hundred sacks can easily be treated at 

 once in such a shed. An entire day should be allowed for each treatment. 1 



As the potato scab is not only carried to the field by the seed, 

 but remains in the soil from season to season, it is of the utmost 

 importance that potatoes be used in rotation with other crops, so 

 as to allow as long an interval as possible between successive potato 

 crops. This will have a tendency to "starve out" the potato scab 

 in the soil ; then by the use of scab-free treated seed the prospect 

 for a crop of smooth tubers is greatly enhanced. 



Fertilizers. Because the potato tubers are formed in the soil 

 and are subject to diseases which are increased by the use of stable 

 manure and lime, the fertilization of potatoes in a commercial way 

 resolves itself largely into the use of specially prepared commercial 

 manures. If farmyard manure is used, it should be thoroughly de- 

 cayed and applied so as to become thoroughly incorporated with 

 the soil. A good way is to scatter it during the fall or early winter 

 upon a clover sod which is to be turned under for potatoes the 

 following year. It is not advisable, however, to apply the manure 

 to the land immediately before plowing, nor to attempt to incorpo- 

 rate it with the soil at planting time, as is frequently done with 

 many truck crops and with sweet potatoes. Farmyard manure, if 

 applied at the time of planting, seems to have the effect of increas- 

 ing the prevalence of scab, and for this reason its use has been dis- 

 couraged. Properly prepared commercial fertilizers do not have 

 this effect and, when composed of ingredients which are quickly 

 available, produce very satisfactory results. Nearly every firm that 

 manufactures commercial fertilizers on an extensive scale offers 

 for sale a special potato mixture. In general it may be said that 



1 Adapted from Bulletin No. 141 and Bulletin No. 149 of the Maine Agricultural 

 Experiment Station, by W. J. Morse. 



