6 



Control. — Do not plant potatoes on the same land two or more 

 years in succession. Avoid using seed tubers on which the black 

 sclerotia appear. Treat seed tubers, before cutting, with corrosive 

 sublimate solution (2 ounces to 15 gallons of water) for one and 

 one-half hours. Dissolve the corrosive sublimate in a small quantity 



of hot water and dilute 

 to the required strength. 

 Tubers may be placed in 

 sacks or in slatted crates 

 for dipping, after which 

 they should be spread out 

 to dry. It is also conven- 

 ient to have two barrels 

 with spigots near the bot- 

 tom. One barrel is filled 

 with potatoes and these 

 are covered with the solu- 

 tion. After treatment the 

 solution is drawn off and 

 poured over another lot 

 of tubers in the second 

 barrel. The tubers in 

 the first barrel are then 

 spread out to dry and 

 the barrel refilled. The 

 solution may be used 

 three times, it being 

 necessary only to keep 

 the quantity up to the 

 original amount by add- 

 ing more of the same 

 strength. The barrels are 

 set on boxes with a space between for convenience in drawing 

 off the solution into pails. Treated tubers may be planted 

 at once or stored, but care must be taken not to reinfect them 

 by placing in infected sacks, crates or bins. The sacks or crates 

 used for dipping may be employed for storage purposes when 

 drv. 



Fig. 5. — Showing effect of Rhizoctonia on young 

 shoots. (After Maine Experiment Station Bulletin 

 No. 230.) 



