ROOT-KNOT DISEASE OF TOMATOS. 



31 



ROOT-KNOT DISEASE OF TOMATOS. 



Records of Field Experiments on Tomato Sub-soils infested 

 with Eelworms — Heterodera radicicola. 



By R. Robson, M.Sc. 



Following an inquiry from Mr. E. Cousins, of Chelmsford, respecting 

 methods of eradicating Tomato Club Disease from a number of green- 

 houses, certain experiments were carried out during the seasons 19 15, 

 1916, and 1917. 



The information available at the time dealing with this problem 

 is summarized in (1) The Board of Agriculture Leaflet, No. 75, 

 where carbolic acid, gas-lime, naphthalene, and sulphate of potash 

 are referred to as substances more or less efficacious. (2) The Board 

 of Agriculture Journal, January 1912, where the effects of steaming 

 the soil and the use of toluol and carbon bisulphide in sick soils 

 are recounted, and in (3) the Journal of the Department of Agriculture 

 and Technical Institute for Ireland, January 19 14, where the value of 

 copper sulphate in cases of eelworm disease in bulbs is described. 



The question of steaming the soil was considered, but given up 

 because of the great expense that would be entailed, since no steaming 

 plant was available. Time also was a consideration, as only the 

 months of December and January were at our disposal. In any case 

 the top soil was to be removed and replaced by virgin soil, plenty of 

 the latter being available, change of soil being an annual routine 

 matter in the nursery. 



Treatment with chemical substances seemed to be the only plan 

 possible under the circumstances, and the Board of Agriculture 

 recommendation to use carbolic acid was considered. The Leaflet 

 recommends : 



1. "To destroy these eelworms the soil must be thoroughly saturated three 

 times, at intervals of a fortnight, with a solution of one part of carbolic acid 

 in twenty parts of water." 



3. "When soil in a house is infected, it is safest to remove the whole and 

 treat it outside ; the interior of the house should then be thoroughly washed 

 with a solution of one part of carbolic acid in eight parts of water." 



Soil treatment recommendations must stand or fall according to 

 the cost involved. If the saturation of a square foot of soil to a depth 

 of 9 inches cannot be effected with less than 1 gallon of water or water 

 solution, then 1 acre of ground, saturated three times with carbolic 

 acid solution (1 in 20), requires of carbolic acid — 



3 x 4840 X9X^ 0 = 6,534 gallons, 

 costing, at 3s. a gallon, £980 2s. 



