828 Journal of Agricultural Research vol. vi, no. 21' 



Lot 2 in sacks, each holding about 100 pounds. One sack each of 

 bruised tubers of Early Rose, Improved Peachblow, Peoples, Netted 

 Gem, and Pearl and two sacks of bruised tubers of Idaho Rural; also a 

 similar number of sound tubers of each variety. The potatoes were 

 fumigated for 24 hours and then placed in storage. As a check, a similar 

 number of trays and sacks of bruised tubers of each variety and a similar 

 number of trays and sacks of sound tubers of each variety were put in 

 storage without fumigation. The period of storage was from Novem- 

 ber 1, 191 3, to May 10, 1 914. The cellar was well ventilated and com- 

 paratively dry. The temperature throughout the storage period ranged 

 from o° as a minimum to 7. 8° C. as a maximum. 



A careful examination of the potatoes at the end of the storage period 

 revealed the fact that a slight amount of decay had taken place in all of 

 the bruised tubers, whether fumigated or unfumigated. Cultures were 

 made from a large number of infected tubers, and the fungus F. trichothe- 

 cioides was obtained. No apparent difference was noted between the 

 fumigated and the unfumigated lots, and there was no decay in any of 

 the unbruised tubers, whether fumigated or not. The unfumigated 

 potatoes, however, sound or bruised, presented a much better appear- 

 ance than the fumigated potatoes, owing to the injuries in the form of 

 sunken spots which appeared on most of the fumigated tubers caused by 

 the action of the formaldehyde fumes. 



In the fall of 191 5, other experiments to control powdery dry rot by 

 disinfecting prior to storage were undertaken. On September 27, 

 Idaho Rural tubers were dug for the experiment. One-half of the tubers 

 were bruised in the field with the digging fork. Bruised and sound tubers 

 were sacked separately. Twenty-five sacks of bruised tubers and 

 twenty-five sacks of sound tubers were employed in the experiments. 

 Each sack contained about 40 pounds of potatoes. The methods of 

 disinfection were as follows: (1) The formaldehyde dip (1 pint of 40 

 per cent formaldehyde to 30 gallons of water). (2) The mercuric-chlorid 

 dip (4 ounces of mercuric chlorid to 30 gallons of water). (3) Dusting 

 with flowers of sulphur. (4) Dusting with air-slaked lime. The formal- 

 dehyde and mercuric-chlorid solutions were made up fresh for each 

 disinfection. 



The potatoes dug were divided into five lots, each lot consisting of 

 five sacks of bruised tubers and five sacks of sound tubers. On Sep- 

 tember 27, a few minutes after digging, one sack of bruised tubers and 

 one sack of sound tubers were placed in storage without disinfection. 

 One sack each of bruised and sound tubers was dipped for two hours 

 in the formaldehyde solution and then dried and put in storage. One 

 sack each of bruised and sound tubers was dipped for two hours in the 

 mercuric-chlorid solution, dried, and put in storage, one sack each of 

 bruised and sound tubers was dusted with flowers of sulphur and put 



