6 MASS. EXPERIMENT STATION BULLETIN 292 



Spring of 193L — This test was conducted to compare carbon disulfide emul- 

 sion with formaldehyde and to determine the influence of different methods of 

 applying carbon disulfide emulsion on the control of the root-knot nematode and 

 the consequent yield and income of tomatoes. The fall planting of tomatoes 

 was removed on January 16. The chemicals were applied on February 15. One 

 plot received carbon disulfide emulsion as a top drench after the soil had been 

 spaded; in another plot the chemical was applied in the furrows as the soil was 

 being spaded. One bed was treated with formaldehyde alone. Application in 

 each plot was at the rate of 1 gallon per square foot. The beds were planted to 

 tomatoes on February 2\. The planting was cleaned out on July 22. 



TABLE 3. — Comparison of Carbon Disulfide Emulsion with Formalde- 

 hyde AND THE Influence of Different Methods of Applying Carbon 

 Disulfide Emulsion on the Control of the Root-Knot Nema- 

 tode and the Consequent Yield and Income of Tomatoes 



(Spring Crop, 1931. Commercial Greenhouse) 



Carbon Disulfide Formaldehyde No 

 I Emulsion 1 — 50 1 — 50 Treat- 



Spaded In Top Drencli 



ment 



Roots free or relatively free of root-knots. per cent 85 71 72.70 50.00 1.96 



Yield of 100 plants pounds 502 464 437 178 



Gross income from 100 plants at 20 cents per pound $100 40 $92 80 $87.40 $21.36* 



Increase in gross income $ 79.04 $71.44 $66.04 



^ Since approximately 50 per cent of the crop from the control plot was of second grade, the 

 income from that plot is calculated on the basis of an average of 12 cents per pound. 



In this experiment, carbon disulfide emulsion was most efficient in the control of 

 the root-knot nematode, and best yields were correlated with the best control of the 

 pest (Table 3). An application of carbon disulfide emulsion while spading the 

 beds, which provided the most thorough drenching of the soil, gave the best 

 results. The check plot yielded an average of L7 pounds of tomatoes per plant, 

 largely of second grade, compared with an average of 5 pounds from the best 

 plot receiving carbon disulfide emulsion, representing a difference in gross income 

 of 79 cents per plant. Formaldehyde showed considerable value as a nemacide. 



Fall of 193L — This experiment was conducted to determine the compatibility 

 of formaldehyde and acetic acid with carbon disulfide emulsion, and the influence 

 of these combinations on the control of nematode. Comparison was made with 

 an adjacent plot which was steamed with the pan. The beds were treated on 

 August 14 with diluted chemical at the rate of 1 gallon per square foot. The 

 former spring crop was cleaned out July 22. The fall planting was set August 

 22. Records of root infestation were made on January 18, 1932 (Table 4). 



A combination of 1 gallon of formaldehyde and 1 gallon of carbon disulfide 

 emulsion in 50 gallons of water proved as effective as steam applied by the pan 

 method in combating root-knot nematode, although a difference in yield in favor 

 of chemical sterilization resulted. This might be explained by the fact that the 

 chemically treated plots were favored with better pollinating and growing condi- 

 tions. The addition of acetic acid to diluted carbon disulfide emulsion completely 

 removed the soap from the emulsion which was apparently the reason why the 

 combination was ineffective. Formaldehyde and carbon disulfide emulsion were 

 perfectly compatible and gave complete control of the root-knot nematode. 



