EXPERIMENT STATION BULLETINS. 417 



SULPHURIC ACID TREATMENT. 



August 14, 1913, all of the remaining plants were dug from the second 

 plot. The soil was then treated with a solution of one part of commer- 

 cial sulphuric acid to eighty-five parts of water, using one-half gallon 

 of this solution per square foot of soil. August 18th lettuce seed was 

 planted in the treated soil. September 8th lettuce plants were dug from 

 the plot and examined, but no knots were found on the roots. It was 

 not possible to get further data on this plot during the rest of the sea- 

 son, but in the light of experiments performed later in the laboratory 

 at the University of Wisconsin, it is probable that the sulphuric acid 

 treatment did not eradicate the nematodes from the treated soil. In the 

 summer of 1914 the writer examined plants from this plot and found 

 root-knots on them. 



FORMALDEHYDE TREATMENTS. 



It was decided that the third plot should be treated with formaldehyde. 

 In 1912 some preliminary experiments along this line were started. Dur- 

 ing April, 1913, we had an opportunity of seeing the results of these soil 

 treatments with a solution of one part of 40% formaldehyde to fifty 

 parts of water. These treatments had not been successful in eradicat- 

 ing the nematodes from the treated soil; so we decided to double the 

 strength by using 1-25 formaldehyde (1 part of 40% formaldehyde to 25 

 parts of water). May 12, 1913, plot III was treated with a 1-25 solu- 

 tion of formaldehyde, using one gallon to a square foot of soil. May 14th 

 lettuce and cucumber seeds were planted in the treated soil to see if 

 they would germinate and grow before the soil was free from formalde- 

 hyde gas. ' May 31st no lettuce or cucumber plants had come up from the 

 seeds planted May 14th, so the plot was planted with lettuce, cucumber 

 and tomato seeds. June IG, 1913, some of the plants were dug and examin- 

 ed, but no knots were found on the roots. June 30th, the author examined 

 lettuce, tomato and cucumbers plants, but found no knots on their roots. 

 August 11th, he dug up and examined lettuce, tomato and cucumber plants 

 and found some small knots on their roots. This showed that the treat- 

 ment with 1-25 formaldehyde had greatly reduced, for a time, the num- 

 ber of nematodes in the soil, but had not eradicated them. 



August 13, 1913, the writer dug up all of the remaining plants from 

 Plot III, respaded the soil, and then raked it so as to note and remove as 

 far as possible, any pieces of roots which had been broken from the plants 

 in digging. The soil was then retreated with a formaldehyde so- 

 lution made up at the rate of one gallon of 40% formaldehyde to sixteen 

 gallons of water, and applied at the rate of about one gallon of solution 

 to a square foot of soil. August 14, 1913, lettuce seed was planted on this 

 plot to see if it would grow before the formaldehyde gas was out of the 

 soil. September 3, 1913, no lettuce plants had developed from the 

 seed planted August 14th; so the plot was replanted with lettuce seed. 

 September 8, 1913, no plants were up. No further data could be taken on 

 Ihis treatment during the rest of the season; therefore, we came to no 

 definite conclusion relative to the value of this treatment. During the 

 summer of 1914 plants from thig plot were examined and nematodes 

 found in the roots. 

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