Sugar Beet Leaf-hopper 



damaging extent in the territory in which The Great Western Sugar 

 Company operates. 



Its association with the disease known as "curly-top," (Fig. 5, Plate 

 VIII, Page 25),ormore locally as "blight," "western blight" or "whis- 

 kered beets" (Fig. 7, Page 60), has long been known, but just how its 

 feeding produces the malady is not so well known. 



Fig. 2.5. Sugar Beet showing characteristic Curling cf Leaves caused by Curly-top 

 (After Harry B. Shaw, Bulletin No. 181. U. S. Bureau of Plant Industry) 



NATURE OF INJURY 

 Indications of Injury 



The symptoms of injury by this leaf-hopper are to be found upon all 

 parts of the plant. The first to appear is usually an inward curling of the 

 inner leaves. This is associated with a distortion and enlargement of the 

 veins of the leaf (Fig. 5, Plate VIII, Page 25). In severe cases the veins 

 are covered with nipple-like protuberances. As the disease advances 

 the whole plant becomes affected. The leaves become badly crumpled 

 (Fig. 25, Page 124), the stunted roots develop an abnormally large num- 

 ber of fibrous rootlets from the root seams (Fig. 7, Page 60), and the 

 root itself becomes darkened, especially where the rings of fibrovascular 

 bundles show in cross sections (Fig. 26, Page 125). The crown of the 

 beet will often be covered with a sweet gummy substance which exudes 

 from the beet. 



How the Disease is Transmitted 



In some way not at present thoroughly understood, certain so called 

 virulent leaf-hoppers have the power of producing curly-top in healthy 

 beets. A single individual which possesses this power will infect a 

 healthy plant if confined upon it for five minutes.* 



*E. D. Ball. "The Beet Leafhopper and the Curly-leaf Disease That It Transmits. 

 Utah Agricultural College (1917). 



124 



Bulletin No. 155. 



