Family Cruciferae 199 



have proved wilt proof in Maryland, have proven 

 equally resistant under Wisconsin conditions. It is, 

 however, advisable to grow seed in the same locality 

 where the resistant cabbage has been developed. 

 The method of developing resistant varieties is 

 given more fully on p. 374. 



Root Knot 



Caused by Heterodera radicicola (Greef) Mull. 



Root knot is very widespread in the Southern 

 States, but is confined mostly to the light sandy soils. 

 It is often mistaken for club root. Careful observa- 

 tion will show the differences. Root knot is char- 

 acterized by small swellings on the lateral feeding 

 roots. For a description of the parasite and meth- 

 ods of control see p. 49. 



Decay of Cabbage in Storage 



Not all field-grown cabbage is consumed when 

 harvested. A large part of the crop is stored away 

 for winter use. It is estimated by Harter 1 that of 

 the thousands of tons stored every fall, from 10 to 

 50 per cent, is annually lost from decay. With 

 the exception of yellows, practically all the other 

 field rots of cabbage may be active also under storage 

 conditions. Therefore, to store a clean crop we 

 must produce a clean crop in the field and on no 

 account should infected cabbage be allowed in the 



1 Harter, L. L., U. S. Dept. Agr. Bur. PL Ind. Circ, 39: 3-8, 1909. 



