127 



TOMATO. 



Root-knot Eelworm. AmjuUluJa radicola: Tleterodera radicola, 

 Greef. ; Heterodera radicicula, Miiller. 



Heterodeea radicicola. 



1, larva; 2 and 3, females; 4 and 5, eggs in different stages of development: 

 all enormously magnified. ( i from sketch by Ed. ; the other figures after Prof. 

 Geo. Atkinson). 



The Heterodera radicicola is a small Eelworm which causes the 

 growth of knots, or galls, on the roots of many kinds of plants, as 

 those of the Tomato, Cucumber, Potato, Parsnip, Peach, Vine, Lettuce, 

 and many others. These knobs are known as the root-knot disease, 

 and according to the kind of plant, or the circumstances in which it 

 grows, may be of the most various shapes and sizes, from a little knob 

 perhaps not the twelfth of an inch across on Clover root, to large 

 irregular masses of diseased growth, within which the "Root-knot" 

 Eelworms are to be found, of both sexes, and in all stages, together 

 with the eggs. 



This infestation is to be found on the Continent of Europe, and in 

 America, where it has been made the subject of careful investigation ; 

 but it was not until December in last year (1892) that observations of 

 its presence in this country were sent me. In this case it was doing 

 serious mischief by its gall formations on the roots of Tomatoes and 

 Cucumbers; and though these cannot be classed amongst "Farm 

 crops," — and also it is to be hoped that our climate will not suit the 

 Eelworm as a field infestation, — still it has manifestly a power of 

 causing so much loss to growers on a large scale under glass, that the 

 attack appears to need bringing forward. 



In the present case I do not give the name, or the locality, of the 



