Sugar Beet Root-louse 



B. SUCKING ROOT FEEDERS 



I. SUGAR BEET ROOT-LOUSE 



(Figs. 1 to 9, 11 to 13, 16 to 18, Plate II, Page 13) 



Because of its universal distribution in the sugar beet growing sections 

 of the West and the difficulty of controlling it, the sugar beet root-louse 

 presents one of the most serious insect pest problems with which the 

 beet growers and factory people have to contend. 



NATURE OF INJURY 



Visible effects of root-louse injury on the above-ground parts of the 

 sugar beet do not appear until the number of lice becomes very great. 

 At such times the color of the beet leaves changes from a dark to a yel- 

 lowish green. This change in color alone must not, however, be taken 

 as proof that a crop is being greatly damaged by root-lice. Sugar beets, 

 especially when grown on light soil or watered too heavily, will turn 

 light in color in the latter part of the season when not infested with root- 

 lice. When the lice become very numerous the beet leaves wilt as though 

 the crop were suffering from lack of water. Often the beets become so 

 shrunken as to be loose in the ground and very much wrinkled. Such 

 beets are very limber and can be bent almost double without breaking. 



The above is descriptive of exceptional cases. Whether effects are 

 visible or not, if lice are present, on the surface of the roots and in the 

 soil surrounding them will be found a whitish, mold-like substance. 

 Intermingled with this and covered by it will be seen many small, wingless 

 lice of a yellowish white color (Fig. 9, Plate II, Page 13), and if the season 

 is well advanced some darker winged lice (Fig. 7, Plate II, Page 13) as 

 well. 



The effect of lice on livestock is so well known that no one expects 

 a lousy animal to make normal growth or put on fat. The loss of blood 

 and possibly the irritation caused by the feeding of the lice stunt it and 

 produce a very scrubby and inferior animal. The effect of lice on a sugar 

 beet may be compared with that of lice on livestock. The lice take up 

 the sap of the beet and the feeding irritates it. The combined effect of 

 these two things is a small, stunted beet and one low in sugar content. 

 Of course quite satisfactory yields and sugar contents are possible even 

 though the beets are lousy. Nevertheless, nothing is more certain than 

 that had they not been lousy both would have been higher. 



Carefully conducted tests show that infested beets contain from |% 

 to 1 % less sugar than uninfested beets in the same field. Also, the purity 

 of juice of such beets is from 1% to 2% lower than uninfested beets. 

 The average infestation reduces the yield by more than 1 ton per acre. 

 In very severe cases the beets are killed or made worthless for factory 

 purposes. 



METHODS OF CONTROL 



There is no known means of entirely preventing sugar beet root- 

 louse losses. However, if the crop is properly handled they can be 

 greatly reduced. 



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