CARBON DISULFIDE EMULSION 3 



Fresh lettuce roots with attached galls not in excess of j inch in diameter 

 were added to nematode infested soil in three 8-inch pots on November 6, 1930. 

 Similarly, fresh tomato roots with attached galls not in excess of t> inch in diameter 

 were added to another set of three pots. On that date, and 10 and 20 days later, 

 the contents of one pot of each series was drenched with carbon disulfide emulsion 

 of a concentration of 1-50 in water. A few days after the treatment the pots were 

 seeded to tomatoes. The roots were examined on the following April 13 (Table 1). 

 The freedom of the roots from nematode root-knots offered convincing and sup- 

 porting evidence of the nemacidal value of carbon disulfide emulsion, and the 

 necessary encouragement to justify further tests under commercial conditions of 

 culture. Several experiments have been conducted over a period of three years. 



TABLE 1. — Control of Root-Knot Nematode \vith Carbon Disulfide 

 Emulsion. 



On November 6, 1930, 8-inch pots were filled with soil in which were embedded roots with root- 

 knots attached; the soils were treated the same day and 10 and 20 days later, and then seeded to 

 tomatoes. 



Source of 

 Inoculum 



Date of 

 Treatment 



Root Infestation April 13, 1931 



Treated 



Not Treated 



Lettuce roots. 



Tomato roots. 



(11-6-30 



.-! 11-16-30 



[11-26-30 



f 11-6-30 

 11-16-30 

 11-26-30 



Apparently none Slight 

 Apparently none Severe 

 Apparently none Slight 



Apparently none 

 Apparently none 

 Slight 



Severe 

 Severe 

 Severe 



GREENHOUSE EXPERIMENTS 



The tests were conducted in greenhouse ground beds heavily infested with 

 nematode where, in the absence of sterilization, the crops have proved a complete 

 failure as the data will show. The experiments were located in the north end of 

 one of the greenhouses of Corazzini & Company, and at the Field Station of the 

 Massachusetts Agricultural Experiment Station in Waltham. Tomatoes were 

 employed as the crop plant in every case. 



Methods 



Materials. — The materials used in the preparation of stock carbon disulfide 

 emulsion and the quantities of each are as follows: 



Volume Weight 



Material (Gallons) (Pounds) 



Carbon disulfide 68 680 



Rosin fish oil soap 6 54 



Water 26 208 



The exact amount of stock emulsion needed was calculated in each case accord- 

 ing to the area of the greenhouse bed. The required amounts of soap and water 

 were niixed together in a wooden barrel, or similar container, and stirred vigorously 

 with a long-handled shovel. The carbon disulfide was added last, while stirring. 

 The stock emulsion of carbon disulfide was used at various dilutions with water, 

 as reported in each experiment. In some instances commercial 37 per cent 

 formaldehyde and 56 per cent acetic acid were used in combination with diluted 

 carbon disulfide emulsion in the proportion reported in the experiments. 



