1724 



ENCYCLOPEDIA OP PRACTICAL HORTICULTURE 



proximately 10 pounds of potatoes per 

 cubic foot or 167 bushels per 1,000 

 cubic feet. With smaller quantities the 

 tubers are liable to be injured by the 

 treatment; while with larger quantities 

 the treatment may not be effective. If 

 necessary to treat smaller quantities than 

 10 pounds per cubic foot it is suggested 

 that a smaller room be fitted up for a 

 fumigator if possible, or that the quan- 

 tity of chemicals be reduced propor- 

 tionately. No tubers should be placed 

 directly above the generator. If possible, 

 the treatment should be made before the 

 tubers have begun to sprout as sprouted 

 tubers are more liable to injury. The 

 temperature of the chemicals at time of 

 mixing should be above 50 degrees 

 Fahrenheit. 



Formaldehyde Solution 



Mix one pint of 40 per cent formalde- 

 hyde solution with 30 gallons of water. 

 Soak the uncut tubers in this solution 

 for two hours. The same solution may 

 be used repeatedly. Treated tubers not 

 required for planting may be used for 

 food or fed to animals with perfect 

 safety. 



Corroshe Sublimate Solution 



Prepare a solution containing 2 ounces 

 of corrosive sublimate in 15 gallons of 

 water. This is best done by first dissolv- 

 ing the corrosive sublimate in a small 

 quantity of hot water and afterward di- 

 luting to the required amount. Soak the 

 uncut tubers in this solution one and one- 

 half hours. Recent investigations by 

 Gussow and Shutt in Canada indicate 

 that the strength of corrosive sublimate 

 solution decreases so rapidly with use 

 that it is necessary to reject it after 

 using three or four times. As the solu- 

 tion corrodes metals it should be used 

 only in wooden or stone vessels. These 

 should be kept away from animals until 

 very thoroughly cleansed from the solu- 

 tion. It is very poisonous. All treated 

 tubers should be either planted or 

 buried. 



With any of the scab treatments care 

 should be taken that treated tubers are 

 not reinfected by coming in contact with 



bags or crates which have held scabby 

 potatoes. 



New Yoik (Geneva) Bulletins 369 and 370 



RossETTE. See Rhizoctoma, this sec- 

 tion. 



Russet Scab 



A russet scab has been reported as 

 more or less common in a number of 

 states, and has been attributed to the 

 Rhizoctonia fungus, but the cause is not 

 well understood. 



Silver Scurf 



This is a new fungus disease, Spondy- 

 locladium atrovirens Harz, introduced 

 from Europe. The disease appears as 

 small dark spots on the skin. In storage, 

 these spots enlarge and the tuber shrivels 

 and becomes somewhat silvery in appear- 

 ance. 



Control 



It is very doubtful if this disease can 

 be controlled by seed disinfection, hence 

 seed selection is the only alternative. 



Soft Eots 



Yarious Causes 



Several soft or wet rots commonly 

 affect tubers in the field or after storage. 

 They seem to be caused in each case by 

 bacteria, and are not to be confused with 

 the Fusarium or PhytopMhora dry rot, 

 although they often follow these as well 

 as scab injury. Dig the potatoes as soon 

 as possible if wet weather prevails and 

 they have been grown in heavy soil. Store 

 in a dry, cool, well-ventilated place. Ro- 

 tate crops and avoid using seed potatoes 

 from affected hills. If possible, use hardy 

 strains. 



Southern Bacterial Wilt. See Black- 

 Leg, this section. 



Stem Blight. See RTiizoctonia, this 

 section. 



Stem Rot. See BMzoctonia, this sec- 

 tion. 



Sun Scald 

 Symptoms 



Wilting and burning of the tender 

 young leaves in June and early July dur- 

 ing very bright, hot weather; especially 

 likely to occur after a period of warm 

 cloudy weather The youngest upper 

 shoots suffer first and worst. 



