ILLUSTRATIONS. 



PLATES. 



Page. 

 Plate I. Fig. 1. — Beet leaves affected by curly-top; also a beet leafhopper. 



Fig. 2. — Dock leaf spotted by punctures of beet leafhopper. 42 



II. Fig. 1. — Sugar-beet seedlings and leaves in a healthy conditioi and 

 others affected by curly-top. Fig. 2.— Healthy and curl; -top 

 sugar beets of medium size 42 



III. Fig. 1. — Large sugar beet affected late in the season by curly-top. 



Fig. 2. — Sections of healthy and curly-top sugar beets, showing 



the discoloration of fibro- vascular bundles 42 



IV. Fig. 1. — Seed beet exhibiting inward type of curl. Fig. 2. — Seed 



beet with long, sinuous type of leaves caused by curly-top 42 



V. Fig. 1. — Seed beet showing retracted type of curl. Fig. 2. — Seed 

 beet showing both inward and retracted type of leaf-curl and 

 seed beet with rosette of severely retracted leaves and no seed 



stem 42 



VI. Fig. 1. — Curly-top seed beet maturing seed. Fig. 2. — Seed beet 



slightly affected by curly-top 42 



VII. Healthy seed beet of same a«ie as that shown in Plate VI, figure 2. 42 

 VIII. Fig. 1. — Seed beet badly affected by curly-top and root almost 

 destroyed by rot. Fig. 2. — Seed beet with sound root, though 



badly affected by curly-top 42 



IX. Fig. 1. — Two young sugar beets showing curly-top symptoms under 

 test conditions with leafhoppers. Fig. 2. — Portion of a cabbage 

 leaf showing curly-top symptoms aftei leafhopper attacks 42 



TEXT FIGURES. 



Fig. 1. Healthy sugar beets, Vilmorin type 10 



2. Curly-top sugar beet, face of leaves, showing retracted type of curl 11 



3. Curly-top sugar beet, dorsal surface of leaves; the same plant shown 



in figure 2 12 



4. Isolation cage and Mason jars for isolating sugar-beet plants 15 



5. Another type of isolation cage 15 



6. A simple method of preparing iron hoops for cages, etc 16 



7. Mature healthy seed beet 26 



8. Sugar-beet seed stems showing curly-top symptoms 27 



9. Average seed yield of healthy and curly-top sugar beets 30 



33801— Bui. 181—10 2 7 



