Sick Soils 25 



female, especially in the posterior region of the 

 body, which no longer possesses a tail-like appen- 

 dage. Fertilization occurs soon after this molt, and 

 many radical changes occur in the shape and struc- 

 ture of the organization of the worm. The fer- 

 tilized female increases rapidly in breadth and be- 

 comes a pearly white flask or pear-shaped individual. 

 At this stage it is far from being worm-like and 

 may, therefore, be overlooked by one unfamiliar with 

 the life-history of the eel worm. The young male 

 is much like that of the young female larvae, being 

 spindle shaped in outline. The male does not cause 

 as much damage to the root tissue as the female, 

 and its purpose in life seems to be only that of fer- 

 tilizing the female, for after this function has been 

 performed, it is quite probable that the male worm 

 takes no more food. 



Omnivorous Nature of the Eel Worm. There are 

 two hundred I thirty-five species of plants known 

 to suffer fron le eel worm. This number includes 

 all the important families of the flowering plants. 

 According to Bessey * the following are among the 

 greenhouse plants subject to root knot: bean, beet, 

 cantaloupe, cauliflower, cucumber, egg-plant, lettuce, 

 radish, tomato. For methods of control, see p. 40. 



Leaf Blight Nematode 



Caused by Aphelenchus olesistus Rizema-Bos. 

 Beside the root knot disease which is caused by 



•Bessey, E. A., U. S. Dept. Agr. Bureau PI. Ind. Bui., 217: 7-8^ 

 1911. 



