428 STATE BOARD OF AGRICULTURE. 



FORMALDEHYDE GAS. 



When large quantities of potatoes are to be treated formaldehyde gas 

 may be used to advantage as follows: (Recommended by the Maine 

 Station Bui. 149.) "Place seed tubers in bushel crates or shallow slat 

 work bins in a tight room. For each 1000 cubic feet of space spread 23 

 ounces of potassium permanganate evenly over the bottom of a large, 

 flaring pan or pail placed in the middle of the room. Pour over* this 

 three pints of formalin. Close room at once and do not open for 24 

 to 48 hours." 



IMPORTANCE OP SOIL CONDITIONS, 



Scabby potatoes are more common on clay and loam than on sandy 

 soil. These soils are more apt to be acid, and on acid soil scab is not 

 common. The scab fungus does not thrive in this kind of soil. Soils 

 which are neutral or slightly alkaline are most favorable to scab. Un- 

 fortunatel}', the soil conditions most favorable to large yields are also 

 most favorable to the growth of the scab fungus. 



LIMB, ASHES AND STABLE MANURE. 



Putting lime, wood ashes or stable manure upon the potato field tends 

 very much to increase the trouble with scab. These substances lessen 

 the acidity of the soil and thereby make it more favorable for the growth 

 of the fungus which may be in the soil. They do not cause the scab as 

 some believe, simply make favorable conditions for its growth. 



USE OF GREEN CROPS AND FERTILIZER. 



By plowing under some gi*een crop like clover or rye a soil that has. 

 become alkaline may be brought back to an acid condition. This is 

 some help but cannot be relied upon to entirely prevent scab. An ap- 

 plication of sulphate of ammonia will reduce the loss from scab as well 

 as supply plant food. 



ROTATION OF CROPS. 



A rotation of crops will assist, considerably, in the control of scab. 

 On soil badly infested with scab it is usually cheaper to abandon potato 

 culture for a time than to try and combat the disease. Scab may persist 

 in the soil several years — just how long is unknown. Much depends on 

 the treatment of the soil and kind of crops grown. Probably, the time 

 is shorter in tilled land than in sod. Beets harbor scab; so do turnips, 

 probably. 



H. J. EUSTACE, Horticulturist. 



