DESCRIPTION OF PLATES. 



Plate I. Work of the beet leaf hooper (Eutettix tenella Raker). Fig. 1. — 

 Beet leaves affected by curly-top; also a beet leafhopper. (A) A beet leaf 

 with inward curl and pronounced vein symptoms; (B, C) two small beet 

 leaves with retracted type of curl; (D) beet leafhopper, adult. Fig. 2. — 

 Dock leaf (Rumex crispus L.) spotted by punctures of beet leafhopper. 

 These spots are of dark crimson-lake, punctate but gradually becoming 

 diffuse ; on the fibro-vascular bundles they become lanceolate. Natural size. 



Plate II. Work of beet leafhopper on seedling beets. Fig. 1. — Healthy and 

 curly-top sugar-beet seedlings and leaves. (A) Healthy seedling; (B) 

 curly-top seedling with well-developed hairy-root, bowed petioles, vein 

 symptoms, and leaf curl; (C) front view of an inner leaf from plant B, 

 showing marginal curl; (D) dorsal view of similar leaf, showing vein symp- 

 toms. Fig. 2. — Healthy and curly-top sugar beets of medium size. (A) 

 Curly-top beet with hairy-root, tough and fibrous root, wide crown with 

 many imperfect leaves sprouting therefrom ; ( B ) beet in perfect health. 



Plate III. Effects of leafhopper attacks. Fig. 1.— Large sugar beet affected 

 Ir.te in the season by curly-top. The retracted type of curl appears to be 

 produced by leaf hoppers when they attack a large beet in considerable 

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

 the discoloration of fibro-vascular bundles. (A) Longitudinal and (B) 

 oblique sections of a healthy sugar beet, showing the very light, delicately 

 traced fibro-vascular bundles of the root. (C, D) Similar sections of a 

 curly-top beet, showing the dark areas, dark fibro-vascular bundles, and 

 blackened area with incipient cavity near crown; (E, F) similar sections 

 of curly-top beet, showing more pronounced blackening of bundles and a 

 cavity with black walls near crown. 



Plate IV. Seed beets affected by curly-top. Fig. L— Seed beet exhibiting in- 

 ward type of curl. Fig. 2.— Seed beet with long, sinuous type of leaves 

 due to curly-top ; this type never produces a seed stem. 



Plate V. Seed beets affected by curly-top. Fig. 1.— Seed beet showing re- 

 tracted type of curl. The greater portion of seed beets thus affected have 

 this type of leaf-curl. Fig. 2. — (A ) Seed beet showing both inward and re- 

 tracted types of leaf-curl; (B) seed beet with rosette of severely retracted 

 leaves and no seed stem. With this type of curl no seed stem ever de- 

 velops. 



Plate VI. Seed stems of curly-top beets. Fig. 1.— Curly-top seed beets matur- 

 ing seed. Fig. 2.— Seed beet slightly affected by curly-top; very slight 

 symptoms of the disease are apparent; the trouble is shown principally in 

 the checking of growth. Compare with Plate VII, which show's a healthy 

 seed beet of the same age photographed to the same scale. 



Plate VII. Healthy seed beet of same age as that shown in Plate VI, figure 2. 



Plate VIII. Root conditions of seed beets affected with curly-top. Fig. 1.— 

 Seed beet badly affected by curly-top and root almost destroyed by rot. 

 (Probably Phoma betae or Rhizoctonia.) Rot not caused by the curly-top. 

 Pijr. 2. — Seed beet with sound root, though badly affected with curly-top. 

 This root was as crisp and sound as when siloed more than seven months 

 earlier. 



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

 test conditions with leafhoppers. These plants were placed under i-gallon 

 Mason jars with two to four leafhoppers, and the disease developed as 

 the result of their attacks. Mason jars shown in the background over 

 other beets. Fig. 2.— Portion of cabbage leaf showing curly-top symptoms 

 after leafhopper attacks; no visible spotting of leaves. These cabbages 

 grew in a small plat between two badly leafhopper-iufested fields; many 

 leafhoppers were noted feediug on the outer leaves of the cabbages. 



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