10 



THE CURLY-TOP OF BEETS. 



together instead of opening out and spreading (PI. II, fig. 2, and 

 PI. Ill, fig. 1). 



The foliage is generally of a dark, dull-green color and quite 

 brittle, though thick and leathery in appearance. In severe cases, 

 especially among young plants, the outer leaves soon become yellow, 

 die, and turn brown ; the inner whorls follow, until the entire plant is 

 killed. 



The roots throw out dense masses of rootlets from the two spiral 

 grooves ; hence the names " hairy-root " and " whiskered beets." 



(See PI. II, figs. 1 and 

 2.) The root itself 

 looks tough and fibrous 

 and in many cases be- 

 comes sprangling. 

 When pulled up, 

 masses of soil cling to 

 the hair -like rootlets 

 and are with difficulty 

 shaken off. The growth 

 of every portion of the 

 plant is checked, if not 

 entirely arrested. 



In many cases the 

 leaf - curl assumes an 

 alternative form. In- 

 stead of an inward 

 curl, the leaf as a whole 

 becomes strongly re- 

 tracted and each por- 

 tion between the larger 

 veins is puffed out. 

 This results in a blis- 

 tered or "savoyed'' ef- 

 fect. In this latter type 

 the vein symptoms are 

 not usually so pro- 

 nounced. Sometimes 

 the two types are com- 

 bined; the leaf as a whole is then retracted, but the margin curls 

 inward (figs. 2 and 3). Frequently wine-colored stains develop in 

 the form of small circular spots over the surface of leaves of mangel- 

 wurzels and garden beets, but no local discoloration has been noted on 

 sugar beets except a faint mottling of young leaves which can only be 

 seen by transmitted light. 



181 



Fig. 1. — Healthy sugar beets, Vilmorin type. (For com- 

 parison with beets affected by curly-top.) 



