ROOT-KNOT EELWORM. 



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EOOT-KNOT EEL WO EM. 



Root-knot Eelworm. Amjuillula radicicola; Heterodera radicicola, 

 Greef. ; Heterodera radicicola, Milller. 



Heteeodkea radicicola. — 1, larva; 2 and 3, females; 4 and 5, eggs in 

 different stages of development : all enormously magnified. (2 from sketch by 

 E. A. O. ; the other figures after Prof. Geo. Atkinson.) 



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 (under glass with us), 

 Potato, Parsnip, Peach, Vine, Pear, Walnut, Lettuce, and 

 many others where climate is suitable for development of this 

 root scourge in the open air. 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 " Koot-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 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 it is 

 to be hoiked that our climate will not suit this Eelworm as an 

 orchard crop root infestation, still it has manifestly a power of 



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