THE CONTROL OF COTTON WILT AND BOOT-KNOT. 7 



Ml a lis of (lisirihiiiion. — \ViJt is spread by direct growth through 

 the soil, by cuhivation, by drainage water, by cattle, by manure, 

 and in other ways not always explainable. No attempt to check it 

 has ever succeeded. 



Koot-knot is generalh' brought to a farm on figs, peaches, or other 

 plants purchased, and after its introduction it is propagated cliiefly 

 by growing ordinary cowpeas, which are quite susceptible. 



Varietal r(.<<istance. — Varieties of cotton resistant to wilt have 

 develojied. Tlio only successful method of control appears to lie 

 along this line. Kesistance to root-knot may be secured by future 

 breeding, but at present this disease must be controlled by proper 

 rotations. 



Wih and root-knot generall}' occur together. Most cases of 

 "black-root " consist of such mixed infections and require a rotation 

 to be })racticed before resistant varieties will give their best results, 



THE CONTROL OF ROOT-KNOT BY CROP ROTATION. 



The ]>rinci]iles on which rotations for the control of root-knot 

 are based are the use of crops immune from attack and, as far as 

 po.s.sible, tliose which return a profit, the building up of the fertility 

 of the soil, and, furthermore, the eradication of all weeds subject 

 to root-knot. Rotation and diversification of crops are of funda- 

 mental importance to southern agriculture ever3^"here and become 

 absolutely necessary wliere the root-knot nematode is present. 



The rotations necessary are of a special character, as indicated 

 below : 



CROPS IMMUNE TO ROOT-KNOT. 



Barley. 

 Beggarweed'. 

 Brabham cowpea. 

 Com. 



Crab-grass. 

 Iron cowpea. 



Peanut . 



Rye. 



Velvet bean. 

 Wheat. 



Winter oats. 



CROPS SUSCEPTIBLE TO ROOT-KNOT. 



Alfalfa. 



.Vsjiaragns. 



Bean.s. 



CantaloupH. 



Celery. 



Clover. 



Cotton. 



Cowpea.s (all except Iron and Brabham). 



Cucumbers. 



Figs. 



H-U:'.<2] 



Mulberries. 



Okra. 



Peaches. 



Soy beans. 



Sugar cane. 



Sweet potatd 



Tobacco. 



Tomatoes. 



Vetch. 



Watermelon. 



