VEGETABLE AND FIELD CHOPS 271 



since the disinfection is more thorough if the surfaces are 

 dry. 



The cost of materials for treatment need not amount to 

 over one cent a 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 formaldehyde, costing $1.20; total, $1.80. Two 

 hundred sacks can easily be treated at one time in such a 

 shed. 



Small quantities of potatoes may be disinfected by soak- 

 ing in a solution of 1 pint of formaldehyde to 30 gallons 

 of water for 2 hours, or 1^ hours in corrosive subUmate 

 solution, 2 ounces to 2 gallons of hot water, then diluted to 15 

 gallons. Either the gas or the solution treatment may be 

 appUed some time previous to planting, provided the pota- 

 toes are not exposed to reinfection by being put into recep- 

 tacles, bags, buckets, etc., that have previously held scabby 

 potatoes. The treatment should be made before the pota- 

 toes are cut for planting. 



No system of soil treatment has proved reliable ki the 

 management of infected land. Long rotation avoiding 

 susceptible root crops should be practiced. The use of 

 fertilizing materials which favor the fungus should be avoided 

 and resistant varieties should be planted. The turning 

 under of a green crop, e.g., rye, may gradually decrease the 

 scab tendency, ^i „.^,^.v 



Rosette, stem 'rot, little potato (Corticium vagum B. & C. 

 var. solani Burt.). — Though particularly prevalent in the 

 Middle West and Rocky Mountain states this pest is known 

 generally in the east from Connecticut south. 



Aerial potatoes, potatoes borne upon the parts of the stem 



