Sugar Beet Nematode 



Root-knot Nematode or Gallworm 



DESCRIPTION AND LIFE HISTORY 



In the course of its development the sugar beet nematode passes 

 through four forms or stages: the egg, two larval stages, and the adult. 



The Egg 



Each adult female produces from 300 to 400 eggs. These are color- 

 less and broadly oval or kidney-shaped. They are extremely small, 

 being only about g ^-o of an inch long. 



The Larval Stages 



The young nematodes, or larvae, are very active, threadlike creatures. 

 Being colorless and almost microscopic in size, they are seldom noticed 

 in the field. 



It is in the first larval stage that the nematodes enter the tissue of 

 the beet roots. The first larval skin is cast shortly after entering the 

 beet and the larva takes on a more robust form. 



The Adult 



With a second molt the nematode becomes an adult male (Fig. 10, 

 Plate III, Page 15), or female (Fig. 8, Plate III, Page 15). 



The Brown-cyst Stage 



As cold weather approaches or conditions become unfavorable for 

 the development of the females, certain individuals pass into a resting or 

 preservation stage which is known as the brown-cyst stage. 



In the cyst form the female passes the winter or the period of un- 

 favorable conditions protecting the eggs until conditions become favor- 

 able for further development. With the change of conditions the eggs 

 begin to hatch. They do not all hatch at once, however, but may con- 

 tinue to do so ror long periods that may extend over several years. 



3. ROOT- KNOT NEMATODE OR GALLWORM 



This nematode, which is very closely related to the sugar beet nem- 

 atode, seriously interferes with the growing of sugar beets in some 



localities. 



This nematode has been 

 found in the Sterling, Brush, 

 Ft. Morgan and Scottsbluff 

 districts. 



NATURE OF INJURY 



The roots of infested plants 

 present a very characteristic 

 appearance. The presence of 

 the females and larvae in a 

 root is indicated by irregular 

 swellings (Fig. 8, Page 64), 

 caused by the irritation set 

 up by these eelworms. 



Pig. 8. Small Sugar Beets infested with the 

 Root-knot Nematode. The bead-like swellings 

 on the small roots and the enlargements of the 

 main root are caused by the nematodes. 



64 



