Fiber Plants 347 



root. All diseased plants have diseased roots marked by 

 injured rootlets and shrunken tap roots, accompanied by 

 depressed spots which are at first bordered by red dis- 

 coloration. The causal fungus is also apparent here, at 

 first as a white mold which later turns brown or yellow 

 and is finally accompanied by wart-like sclerotia. En- 

 largements, from which new roots are put forth, often occur 

 near the soil surface. Even the lint of the diseased plants is 

 affected, the fibers being wider and larger, and the spirals 

 fewer and more uneven, than upon healthy plants. The 

 disease is truly of the soil, and the affected soil centers en- 

 large yearly as in other soil diseases. It is subject to the 

 modes of dissemination suggested on page 29. 



Extreme precaution should be exercised against the use, 

 for the purpose of legume inoculation, of soil which may 

 possibly be infested with the disease. This warning is 

 particularly necessary in view of the fact that alfalfa is 

 affected by the same disease, and the causal fungus is now 

 present in many alfalfa fields. 



As to treatment, rotation with immune crops (see p. 23) 

 in conjunction with deep fall plowing is recommended. 

 To quote from Shear and Miles: "Rotation with immune 

 crops at Terrell, Tex., resulted as follows: 1904, planted to 

 cotton, about 95 per cent of which was killed by root rot; 

 1905, planted to corn; 1906, planted to wheat, followed by 

 sorghum the same season; 1907, cotton again planted, 

 with the result that, as nearly as could be estimated, less 

 than 5 per cent of the cotton was dead at the close of the 

 season. 



"Land badly infected with the root rot was plowed seven 

 to nine inches deep November 11, 1906, at Petty, Tex. In 

 experiment No. 1 the deep-plowed plat showed 42.75 per 

 cent less dead plants than the adjoining check plat which 

 received the customary tillage. In experiment No. 2 the 

 deep-plowed plat showed 43 per cent less dead plants than 

 the adjoining check plat, and in both cases a much larger 

 amount of cotton was produced on the dead plants on the 



