10 



NEMATODE GALL.WOEM ON POTATOES, ETC., IN NEVADA. 



In. figures 6, 7, 8, 9, and 10 are shown the results of gallworm injury 

 on tlie peacli, tlie grape, the willow, the fig, and cotton. These plants 

 are all distinctly susceptible to gallworm injury and may serve to 

 indicate the presence of tliis worm if it occurs abundantly in the soil. 

 Figure 1 1 shows the enlargements on the roots of a cowpea caused by 

 the nematode. These enlargements are characteristic and need not 



Fig. 9.— Roots of the fig, 

 shovring enlargements 

 caused by the nema- 

 tode gallworm. The fig 

 is very susceptible to 

 the attacks of this para- 

 site and, though when 

 the roots are severely 

 infested the tops may 

 continue to grow when 

 conditions are favor- 

 able, in times of drought 

 or in cold weather the 

 diseased plants suffer 

 severely. (After J. C. 

 Neal.) 



Fig. 10. — Roots of cotton, showing en- 

 largements caused by the gallworm. 

 Owing to the wide prevalence of this 

 worm in the southeastern United 

 states, the aggregate annual damage 

 whiich it causes on cotton is very large, 

 though not generally appreciated. 

 (After George F. Atkinson.) 



Fig. U.— Roots of the cowpea, 

 showing enlargements caused 

 by the gallworm. With the 

 exception of one variety (the 

 Iron cowpea) tliis plant is very 

 susceptible to the gallworm, 

 and the use of susceptible va- 

 rieties as green-manure crops 

 in peach orchards and in rota- 

 tions just preceding cotton in 

 the South is to be avoided. 

 (After J. C. Neal.) 



be confused with the nodules caused by the nitrogen-gathering bac- 

 teria wliich inhabit the roots of this plant. The nodules caused by 

 the nitrogen-fixing bacteria are small and spherical and are attached 

 to the side of the rootlets, whde the nematode causes the swelling of 

 the root itseK. Figures 12 and 13 show the effect of the attack of 

 the gallworm on red clover and also the worm as it is found in the roots. 

 In figure 12 the enlargements on the roots are shown, while in figure 

 13 the sections of the root show the presence of the gallworm larva\ 

 Figure 14 shows the enlargement caused by the gallworm on the roots 



[Cir. 91] 



