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 piipse of this pest. 



The Parsnip Fly {Psila rosce) has already been 

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



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



A. A spotted parsnip. 



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



C. Matare conidimn dividing, x 334. 



D. Conidimn after division. The formation of zoospores, x 334. 



E. Zoospore with cUia. x 331. ■ 



The Parsnip Moths have already been described 

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

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



The Parsnip Mildew (Peronospora nivea, Mg. 

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

 gus first attacks the leaves, the hyphse of which soon 



