ROOT CROPS. 



47 



and sand to be put on the ground before sowing the seeds. 

 The odour of the tar is so offensive to insects that they 

 cannot endure soil impregnated with it. (2) Burn all in- 

 fested leaves. 



Cure. — Dressing the land with gas-lime, soot, and lime, 

 destroys the pupss of this pest. 



The Parsnip Fly {Psila rosm) has already been 

 described in this chapter (see " Carrot Fly "). 



Fig. 19. — Mildew of Paesnips (Peronospora nivea). 



A. A spotted parsnip. 



B. Coniaiophore bearing ronidia (spores), x 107. 



C. Mature conidium dividing, x 334. 



D. Conidium after division. The formation of zoospores. 

 B. Zoospore with cilia, x 331. 



X 331. 



The Parsnip Moths have already been described 

 under the heading of " Carrot Moths " ; and for still fur- 

 ther information, see Dr. Riley's Insect Life, vol. 1, p. 94. 



The Parsnip Mildew {Peronospora nivea, Fig. 

 19) lives within the tissues of the host-plant. The fun- 

 gus iirst attacks the leaves, the hyphse of which soon 



