ROOT-KNOT DISEASE OF TOM AT OS. 



45 



The results for " powder substances," viz. " V.N.," " V.C," 

 vaporite, and naphthalene may next be considered. 



Table XIII. 



Quantity 

 Applied. 



Substance. 



Plot. 



■ 



Degree of Infection in 1916. 



Jan. 



Oct. 



69 cwt. 



17 » 



112 „ 

 112 „ 



Vaporite \ 

 Naphthalene 

 " V.N." . 

 "V.C." . 



27 

 53 



59 

 60 



XXXX 

 X 



xxxx 



XXX 



xxxx 



XX 



xxxx 



XX 



It appears that " V.C." was the best application of this group. 

 Results were obtained for the first time in these experiments with 

 the following five substances : 



Table XIV. 



Substance Applied. 



Iodine 

 Turpentine 

 Paraffin 



»» • 

 Creosote 



>> • 

 Creosote emulsion 



54 

 50 

 55 

 5i 

 48 



49 

 2 



Degree of Infection Season 1916. 



Plot. 



Quantity per 



Jan. 



Cct. 



acre. 



XX 



XX 



2 I Cwt. 



X 



XX 



437 S'-k- 



XX 



XXX 



1090 



XX 



XXX 



730 » 



X 



XXX 



640 



XX 



XX 



640 



X 



0 



4*7 „ 



The iodine was dissolved in alcohol and the solution was diluted 

 with water and watered into the subsoil. The turpentine and paraffin 

 were emulsified with soap and applied to the plots. The quantities 

 given represent the actual amounts of pure turpentine and paraffin 

 used, not the volumes of the stock emulsions made from them. The 

 creosote in Plots 48 and 49 was applied as a coarse spray, and after 

 application the treated subsoil certainly appeared to be a " poison- 

 stratum." No water was applied. In Plot 2 the number 487 gallons 

 represents pure creosote. It was emulsified with soap at the rate of 

 1 lb. of soap to 1 quart of creosote. The creosote emulsion was the 

 only one of the group which did any good, and it was deemed advisable 

 to use a " home-made " creosote emulsion in 1917 on a larger scale. 



After examining the results of the two years' trials it was decided 

 that potassium cyanide, mercury bichloride, and phenol, in the order 

 given, were the most efficacious vermicides that had been used ; that 

 cresylic acid and creosote emulsion appeared to be on the right lines 

 also, and if applied in greater quantities the results were likely to be 

 attended with success. 



