1210 



EARLE V. HARDENBURG 



CHEMICAL TREATMENT OF SEED 



The chemical treatment of seed potatoes to rid their surfaces of the organ- 

 isms causing common scab (Actinomyces chromogenus) and rhizoctonia 

 (Corticium vaguum) has been sufficiently tested scientifically to warrant its 

 practice wherever these diseases occur. Tho such treatments as immersion 

 in corrosive sublimate or formaldehyde, or fumigation with formaldehyde 

 gas, are not warranted to insure the crop against either of these diseases 

 in the following crop, yet they have invariably reduced the infection to a 

 profitable extent. Ballou (1910) and Gourley (1910), using duplicate 

 plots of untreated seed, seed treated with formalin, and seed fumigated 

 with formaldehyde gas, reduced the scab infection from an average of 

 58.5 per cent in untreated seed to 16.7 per cent in formalin-treated seed 

 and to 18.4 per cent in fumigated seed. The writer (Hardenburg, 1917) 

 reported a reduction of rhizoctonia, in the crops of fifty-eight growers in 

 New York who used corrosive sublimate, to 1.8 per cent infection as 

 compared with 12.7 per cent infection of the crops grown by the remaining 

 twenty-two growers considered. He reported a similar reduction of scab 

 infection, thru formalin treatment by sixty-two growers, to 7 per cent as 

 compared with 10.7 per cent in the crops grown from untreated seed. 



In spite of these -tests and the recommendations based on them, a rela- 

 tively small proportion of growers in the four surveyed regions treat their 

 seed. The percentage doing this in each region is reported in table 47: 



TABLE 47. 



PER CENT OF GROWERS TREATING SEED CHEMICALLY IN THE FOUR REGIONS 

 SURVEYED 



It has not been possible in this study to correlate the apparent need of 

 seed treatment with the actual practice as indicated in this table. This is 

 due partly to incomplete data from the four regions, and partly to a lack 

 of familiarity with diseases on the part of. growers. Such treatment, 

 however, is universally recommended because of the attested saving to 

 the crop. For the four regions, an average of 8.3 per cent of the growers 

 reported scab, and an average of 4.6 per cent reported rhizoctonia, in the 

 crop from which these data were taken. 



