No. 6. DEPARTMENT OF AGRICULTURE. 761 



"8. The treatment of seed tubers by rolling io sulphur and sprink- 

 ling the balance in the row at the rate of 300 pounds per acre is 

 claimed by Halsted to be quite effective. The use of the very poison- 

 ous corrosive sublimate solution would be thereby avoided, yet the 

 additional expense of the sulfur over the corrosive sublimate treat- 

 ment for this purpose militates against its use in that way where 

 potatoes are grown at the present low prices. 



"9. The marked acidity (sourness) of soils, or the absence of car- 

 bonates in them, seems to indicate their ability to produce a scable&s 

 product even when untreated seed tubers are used." 



OUR CONCLUSIONS. 



When danger of scab threatens, all seed should be treated with 

 corrosive sublimate or Bordeaux mixture before planting, and the 

 land should not be given an application of fresh stable manure or 

 lime within a year of planting. Kotation of crops is desirable. If 

 the soil is infested with the fungus, an attempt should be made to 

 produce some acid in it by plowing down a green crop, like rye, in the 

 spring. Lime sfliould not be applied. Rolling the cut seed in sulphur 

 before planting and applying 300 pounds of sulphur in the row, may 

 give good results. Some varieties of potatoes are much more subject 

 to injury from this fungus than others are. Select resistant varie- 

 ties. 



On the other hand continuous planting of potatoes and the use of 

 manure will not bring scabby crops if the fungus germs are not 

 present, or .if they are kept in control by the acidity of the soil. Clean 

 seed, made so by treatment of good tubers with the solution of 

 corrosive sublimate, and selection of resistant varieties do much to 

 save from loss. Drainage is an aid, in that it removes a surplus of 

 moisture. Experiments with irrigation of potatoes indicate that 

 water favors scab development, and in our own experience the dis- 

 ease is worse in wet seasons than in dry ones. Early digging is ad- 

 visable when scab is present. While most scientists regard the 

 worst roughening of the skin as an eifort of nature to heal the injury 

 made by the fungus, yet there is evidence that the injury continues 

 after maturing of the tubers when left in the ground. Exposure to 

 light checks its work. The budding of seed in the sunlight before 

 planting destroys the vitality of the germs. 



Rhizoctonia, — A disease that is new to potato-growers in this 

 country is appearing in fields in many States. In the annual report 

 of the New York Station for 1900, attention is called to it, and we 

 learn that it was observed over ten years ago in Iowa. In 1900 I 

 found the disease in one of my fieldis, losing two-thirds of the crop by 

 its ravages, and learn from our Station workers that it is the soil 

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