NEMATODE GALLWOKM ON POTATOES, ETC., IN NEVADA. 7 



from field to field in any jiarticular district may be accomplished by 

 carrying soU on agricultural im])lcments, on the feet of animals or 

 men, or by transplanting })lants from one field to another. In fact, 

 there are so many ways in which infestation can be accomplished 

 that the greatest precautions should be used to prevent the (Ustribu- 

 tion of infested earth or plants into uninfested areas. The careless 

 disposal of garbage containing infected potato peelings or the spread- 

 ing of manure from yards where infected roots or tubers have been 

 used as stock feed may transport the worm and develop serious 

 infestation. 



Fig. 4. — Microphotopraph of the eggs of the gallworrii and the young 

 worms just hatched, taken from a potato. This appearance is often 

 seen in microscopic preparations made from infested areas of roots. 

 (After F. R. Ileadley.) 



All classes of nureery stock, including strawberry plants, tomato 

 plants, and small fruits, should be examined with great care if they 

 are to be set in fields which it is desired to keep free from this parasite. 



UNINFECTED SEED POTATOES ABSOLUTELY ESSENTIAL. 



In attempting to control this disease it is, of course, absolutely 

 essential to plant uninfected j)<)tatoes as seed. It is not enough to 

 be sure that the j)otatoes planted do not show superficial evidences 

 of the disease; it sliould be determined beyond doubt that there is 

 absolutely no infection present. Tliis can best be assured by securing 



K'ir. 91] 



