54 



BULLETIN 727, U. S. DEPARTMENT OP AGRICULTURE. 



the usual number of rows, twee the ordinary quantity, or about 2 

 pounds of seed, was planted in each field. This allowed a test of 

 about 70,000 seeds per field. 



Table VII. — Effect of seed disinfection upon the occurrence of anthracnose in cucumber 

 fields at Madison, Wis., in 1917. 



Name of 



Area. 



Subdivision. 



Seed treatment. 



Results. 



field. 



On Aug. 13. 



On Sept. 8. 



McKenna 



[One-quarter 



•! acre. 



1 do 



f do 



West half. . . 



East half 



West half... 



East half 



North half. . 

 South half... 



2 per cent formalde- 

 hyde, 1 10 minutes. 



4 per cent formalde- 

 hyde,' 5 minutes. 



0.5 per cent CuSO-t, 10 

 minutes. 



1 per cent CuSOi, 5 

 minutes. 



Hot water, 52° C., 10 

 minutes. 



No anthracnose. 

 do 



No anthracnose. 

 Do. 





do 



Do. 



Brittenbach.l^j 



| ...do 



do 



Do. 



If do 



do 



Do. 



Tobacco . . •! 



1 ...do 



do 



Do. 



Isom 





1916seed, untreated 



1 plant diseased . . 









thracnose. 



1 40 per cent solution. 



Until August 1 careful inspection of all of these fields was made 

 twice each week. A special effort was made to detect an original 

 diseased plant in the Isom field before the thinning and the elimina- 

 tion of the interplanted rows, but no success was attained. Unfortu- 

 nately, the first anthracnose did not appear until a month after its 

 normal date of appearance, and a complication is afforded by the 

 earlier appearance of anthracnose in field 1 as a result of overwinter- 

 ing in the soil. While the Isom field was a considerable distance from 

 field 1 , there is a possibility, even though very slight, of the introduc- 

 tion of the disease by insects, pickers, or cultural operations. Since, 

 however, the other fields were equally exposed to this type of infec- 

 tion, it is significant that anthracnose appeared only in the field 

 planted wdth 1916 untreated seed. This is taken as a rather convinc- 

 ing indication but not conclusive proof of disease introduction with 

 the seed. 



Assuming that anthracnose was present in the 1915 seed, its failure 

 to appear in the south half of the tobacco field has some significance. 

 It suggests that possibly the fungus does not survive the eighteen 

 months' desiccation. 



For the more extensive field tests arrangements w r ere made with a 

 pickling company whereby all of the seed distributed to its growers 

 in one district was to be previously treated, while in a neighboring dis- 

 trict similar seed, untreated, was to be used. This trial was made 

 in triplicate, one trial in each of the three States of Indiana, Wiscon- 

 sin, and Michigan. Both Ohio seed and Iowa seed were thus tested; 

 the former in Indiana and Wisconsin, the latter in Michigan. For 

 the disinfection of all of this seed the treatment of proved effec- 



