CARBON DISULFIDE EMULSION FOR THE CONTROL 

 OF THE ROOT-KNOT NEMATODE 



By E. F. Guba, Assistant Research Professor of Botany 



INTRODUCTION 



Root-knot, caused by the nematode Ileterodera radicicola (Greef) Miill., is the 

 most prevalent and destructive disease of greenhouse cucumber and tomato crops 

 in Massachusetts, and the most costly to control. It is common knowledge that 

 soil applications of steam or hot water give control; nevertheless the need for an 

 efficient chemical control is urgent. Because of the fact that formaldehyde and 

 acetic acid lack satisfactory nemacidal value, their use for controlling soil in- 

 habiting fungous parasites has been largely ignored in greenhouse practice. A 

 more extended use of these soil disinfectants in greenhouses cannot be realized in 

 the absence of a satisfactory chemical nemacide. 



The merit of carbon disulfide emulsion as a nemacide was discovered by 

 Schaffnit and Weber (7) in Germany. Greenhouse tests by Chapman and Parker 

 (1) in Mrginia, and by Gleisberg (3) in Germany, confirmed this discovery. The 

 work in Germany showed that the use of carbon disulfide emulsion can be 

 relied upon to restore normal yields and at a profitable investment. Schaffnit and 

 Weber mixed one part of soap with four parts of carbon disulfide by volume (SO 

 per cent emulsion), and according to their recommendations each square foot of 

 bed received 1.3 to 2.0 ounces of actual carbon disulfide. Chapman and Parker 

 used a commercially prepared 35 per cent emulsion at a dilution of l-.SO in water, 

 and each square foot of bed received about 0.9 ounce of actual carbon disulfide. 

 The merit of carbon disulfide emulsion as a nemacide is thus recognized yet there 

 has been a lack of information that would justify any recommendations to the 

 public on the part of this Station without careful tests in local greenhouses. 

 Information has been needed particularly concerning the best dilution of the 

 emulsion, the rate of application, and other factors which might be expected to 

 have an influence upon its efticiency, cost, and safety under commercial green- 

 house conditions. 



PRELIMINARY CONSIDERATIONS 



Commercially prepared emulsions containing 35 per cent and 70 per cent 

 carbon disulfide were at first compared on a small scale. Each was diluted to make 

 a strength of 1-50 and applied at the rate of 1 gallon to each square foot, equiva- 

 lent to about 0.9 and 1.93 ounces of actual carbon disulfide. Tomato plants were 

 set in the plots 3 days later and were allowed to grow for two months. The tomato 

 roots in the control plot showed a bad infestation of root-knot while those in the 

 treated plots were healthy. The results were very striking. 



The cost of a 70 per cent commercially prepared emulsion at 17 cents per pound 

 in 50-gallon drums is, however, prohibitive in practice, for it means an expense for 

 material alone of $0,034 per square foot or about S1481.00 per acre. A similar 

 homemade emulsion can be made at a cost of $0,009 per square foot, or approxi- 

 mately •S392.00 per acre, excluding labor; and if effective would represent an 

 economical method of control. Such an emulsion was prepared to contain 68 

 per cent carbon disulfide, 26 per cent water, and 6 per cent rosin fish oil soap (No. 

 9)'. 



^Manufactured by I. P. Thomas & Son, Company, Philadelphia, Penn. 

 ^Manufactured by James Good, Inc., 2111 E. Susquehanna Ave., Philadelphia, Penn. 



