30 MAINE AGRICULTURAL EXPERIMENT STATION. 



outside of the house. As much of this material as possible 

 should be burned. What remains unburned should be soaked 

 with a strong solution of copper sulphate. After all rubbish 

 has been removed the interior walls and floors of the empty 

 potato house should be thoroughly sprayed with a solution of 

 copper sulphate, 5 pounds and water 50 gallons. The addition 

 of a small amount of lime will aid in marking the portions cov- 

 ered by the spray. A hand barrel-pump with 25 to 50 feet of 

 hose with an extension rod such as is used in orchard spraying is 

 very satisfactory for this purpose. 



More complete disinfection of empty houses may be secured 

 by the use of formaldehyde gas following spraying with copper 

 sulphate. To accomplish this, make all outside doors and win- 

 dows as tight as possible. For every 1000 cubic feet of contents 

 of the house or room use 23 ounces of potassium permanganate 

 and three pints of 40 per cent formaldehyde. Spread the per- 

 manganate evenly over the bottom of one or more large vessels 

 like a wash tub or half of a kerosene barrel, these latter arranged 

 in the central parts of the floors of the house or rooms. Pour 

 the formaldehyde quickly over the permanganate, being sure 

 that it is well mixed with the latter. Leave and tightly close 

 the house at once. Allow to remain closed 24 hours or longer. 

 Barrels and tools if clean, can be disinfected at the same time, 

 although probably not so thoroughly and efficiently as by wash- 

 ing with formaldehyde solution. Do not attempt to use the gas 

 in the house till after all potatoes and rubbish have been removee 

 and the house cleaned up as described above. 



Sulphur and Common Potato Scab. 



The pathologists of the Station have recently been giving con- 

 siderable attention to the subject of soil disinfectants, particu- 

 larly sulphur, for use upon land infected with common scab, 

 powdery scab, and the Rhizoctonia disease of potatoes. While 

 httle hope was entertained that a satisfactory material could be 

 found which would be sufficiently cheap in price to allow its 

 use in the necessary quantities to ensure success, the question 

 is of so much importance to the potato growers that any possi- 

 bility of success, no matter how remote, should not be over- 

 looked. 



