6 CONTENTS 



Control of root-knot — Continued. 



Control of root-knot in the field when no crop is present — Continued. Page. 



Trap crops 61 



Steam 63 



Fallow 64 



Nonsusceptible crops 65 



Recommendations for freeing a field from root-knot 69 



Breeding strains resistant to root-knot 71 



Summary 72 



Bibliography 76 



Description of plates 82 



Index • • - • 83 



I 



ILLUSTRATIONS 



PLATES. 



Page. 



Plate I. Stages in the development of Heterodera radicicola (Greef ) Mull. , etc . 82 



II. Fig. 1— Root-knot on sugar beet. Fig. 2— Root-knot on squash 82 



III. Fig. 1— Root-knot on carrot. Fig. 2— Root-knot on clover 82 



TEXT FIGURES. 



Fig. 1. Heterodera radicicola. Half-grown female (?) individual shortly 



before the final molt 28 



2. Anterior portion of same nematode shown in figure 1 29 



3 Larva of Heterodera radicicola 29 



217 



