Sugar Beet Nematode 

 NATURE OF INJURY 



The young sugar beet nematodes search out a beet root, and by 

 piercing it with their strong spear-like mouth parts, embed themselves 

 within the tissue. They then begin to feed upon the juices of the beet. 



Effect on Roots 



The presence of the nematodes causes an irritation of the roots. 

 Because of this irritation, and because the sap is consumed by the nema- 

 todes, the roots are unable to carry the water and plant food to the beet, 

 and the growth of the plant is interferred with. 



In an attempt to overcome this trouble the beets send out many 

 new rootlets from the root seams at each side of the main root. In 

 Europe these beets have been called "bearded roots" or "hunger roots." 

 Such beets (Fig. 6, Page 60) resemble the "whiskered beets" suffering 

 from a severe attack of the disease known as "Curly-top" (Fig. 7, Page 

 60). 



If carefully removed from the soil, the rootlets of infested beets 

 will have many minute, pearly-white bodies clinging to them (Fig. 9, 

 Plate III, Page 15). These are the mature female nematodes. 



In extreme cases the weakened roots become infested with fungi and 

 bacteria which cause them to rot or the plants die because of lack of 

 nourishment. 



Effect on Leaves 



The presence of nematodes becomes apparent in the appearance of 

 the leaves as the season advances. The foliage of the infested plants 

 turns light in color, becoming a yellowish green, or they have the dull, 

 gray-green color of beets suffering from lack of water. The leaves wilt 

 and finally lie flat on the ground, failing to recover during the night. 

 The outer ones finally die. The growth of the inner leaves is seriously 

 interfered with, and in severe cases they die also. If the beet does not 

 succumb to the attack, the new leaves produced fail to attain normal 

 size and are often much curled and distorted. Late in the season, beets 

 which have survived the- attack are often a darker green than their 

 uninfested neighbors. 



Effect on Sugar Content 



Not only is the size of the roots and leaves of the beets affected 

 but the sugar content is greatly reduced as a result of the nematode 

 attack. For example, moderately infested beets contained 11.35% 

 sugar and badly infested ones only 8.4% in a field where healthy plants 

 had a sugar content of 14.9%.* 



HOW NEMATODES SPREAD 

 By Their Own Movements 



Sugar beet nematodes have the power of increasing by their own 

 movements the area infested. In certain stages of their development 

 and under favorable conditions they can travel considerable distances 

 in the soil. The ravages of this pest have been known to be extended 

 from 50 to 75 feet each season in this way.* 



*Harry B. Shaw. "Control of the Sugar-Beet Nematode." Farmers' Bulletin No. 772. U. S. Depart- 

 ment of Agriculture (1916). 



61 



