THE POTATO IN JJurnsu COLUMBIA. 71 



in some convenient container to make good the waste as each sack is dipped. 

 Immerse a sack of potatoes, raising it up and lowering it a few times to hasten 

 the penetration of the liquid, and leave for one and a half to two hours. Take out 

 and spread them out to dry on the prepared floor. This method is, however, too 

 slow if large amounts are to be treated. In this case immerse as before for fifteen 

 to twenty minutes ; then take out, put on the prepared floor or on some dipped sacks, 

 and cover with other dipped sacks or canvas to keep in the gas, and leave until one 

 and a half to two hours have elapsed since the first immersion. The sacks can be 

 put out side by side in regular order and the time when the first is taken out noted. 

 They can then be removed from the other end of the pile in the same order, dumped, 

 and spread out to dry. In this way six to eight times as many tubers may be 

 treated in the same time. After removing the sack from the immersion it may be 

 stood for a few minutes in another tub to catch the excess of liquid which drains 

 from it. At ordinary temperatures the liquid does not become appreciably weaker, 

 and it is only necessary to add enough fresh solution to keep the liquid at the level 

 required for full immersion. If more convenient for any reason, the tubers can, of 

 course, be placed directly in the liquid, but as a rule they are much more conveniently 



Fig. TO. Treating seed-potatoes in vats (after Minnesota Bulletin 190). 



handled in sacks. After the day's work is over put into the liquid the sacks, 

 baskets, etc., to be used afterwards in handling the treated tubers, put on the lid 

 of the barrel or cover over, and leave for two or three hours or overnight. Planters, 

 wagons, etc., should all be disinfected, preferably with the stronger solution pre- 

 viously used for the floor, or the liquid left over from dipping may be used. In this 

 case it would be well to wash them down twice. 



Professor Melhus (Iowa Experimental Station Circular 57) has recently pub- 

 lished a method of shortening the treatment by using hot formaldehyde; 2 Ib. of 

 formaldehyde are used to 30 U.S. gallons of water. This is kept at a temperature 

 between 118 and 122 F. The potatoes are dipped for two minutes in the solution, 

 taken out, spread out in a layer 6 to 8 inches deep, and covered with wet sacks for 

 sixty minutes to keep in the fumes. They are then dried. 



In cutting potatoes it is well to have two knives and a small dish of the formalin 

 solution at least as strong as that for dipping. If a diseased tuber is cut, drop the 

 knife into the dish and take out the other. This will avoid contaminating sound 

 luhors with diseased ones. 



