1726 



ENCYCLOPEDIA OF PRACTICAL HORTICULTURE 



Mealy Bugs 

 Tuber Mealy Bug 



Pseudococcus affinis Mask. 



The tuber mealy bug occurs in Aus- 

 tralia, and is found upon the tubers of 

 dahlias and potatoes. 



Solanum Mealy Bug 



Pseudococcus solani Ckll. 



Color 



The body is pale yellowish and sparsely 

 covered with fine white powdery wax. 



Food Plants 



This species appears to be a subterran- 

 nean form and lives either entirely un- 

 der ground or upon the branches which 

 touch the ground. It has been found 

 feeding upon the following plants: Aster, 

 sp. nightshade, pigweed, potato, purslane, 

 wild sunflower, tomato. 



E. O. EssiG 



Potato Eel Worm or Common Nematode 



Heterodera radicicola Greef. 

 General Appearance 



The presence of this pest is told by 

 such characteristic injuries as root knot 

 on nursery trees, galls on tomato vines 

 and the rough warty surface of potato 

 tubers. The animal causing the injuries 

 is commonly known as the nematode 

 worm and was recently given much prom- 

 inence as the potato eel worm. The males 

 and young, the usual forms of the animal, 

 are microscopic, transparent and shaped 

 much like minute eels. The female is 

 pear-shaped and pearly-white. The eggs 

 are oval in shape and laid in great num- 

 bers. 



Life History 



The young eel worms feed upon the 

 roots of various plants causing galls or 

 knots which may greatly impair growth. 

 The female develops within the affected 

 areas and begins egg-laying, the young 

 hatching in a very short time afterwards. 

 The winter is passed in the original host 

 if it remain growing in the soil, such as 

 nursery stock, but if the host is removed 

 they feed upon various plants left in the 

 fields. The young have the ability to en- 

 cyst themselves so as to resist great ex- 



tremes of weather and unfavorable condi- 

 tions, so once in the soil it is very di- 

 ficult to eradicate them. 



Food Plants 



According to Dr. E. A. Bessey there are 

 480 species and subspecies of plants af- 

 ected by root knot. The list includes 

 members of practically every flowering 

 plant. Most of the garden plants are af- 

 fected, as are many of the field crops and 

 fruit trees. For definite information con- 

 cerning the host plants the reader is re- 

 ferred to pp. 10-22, Bulletin 217, Bureau 

 of Plant Industry, U. S. Department of 

 Agriculture, by Dr. Bessey. 



Control 



The control of this pest is extremely 

 difficult and eradication almost impossible. 

 In greenhouses the soil may be sterilized 

 with steam or formaldehyde (one part to 

 100 parts of water). Rotation of crops 

 which are not attacked by the nematode 

 is perhaps the best control measure in 

 the field. Summer fallow, frequently 

 turning up the soil and allowing it to 

 dry out, will help to reduce the num- 

 bers. Irrigated districts are more liable 

 to become infested, and are very favorable 

 to spread and difficult of control. 



E. O. EssiG 



Fig:. 1. Potatoes Showing: the Work of the 

 Common Nematode or Eel Worm, Heterodera 

 radicicola Greef. 



— Photo hy Bremmer 



Potato Tuber Moth 



Phthorimaea operculella Zeller 

 (Family Gelechiidae) 



General Appearance 



The larvae vary from white to slightly 

 pink — the head being black. When full 



