The F^ungus Pests of certain Flowers 



attacks P. somniferum and all its garden varieties. The fungus grows 

 within the leaves, and emerges with a tree-like growth through the 

 organs of transpiration (the stomates) on the under side of the leaves. 

 Like the fungus of the Potato disease, it speedily sets up decomposi- 

 tion, and destroys the host-plant. 



At A is illustrated one of the stems of the Poppy Peronospora 

 emerging from the leaf, enlarged seventy-five diameters. The fungus 



of the Poppy is very much 

 more branched than that of 

 the Potato, and every minute 

 branchlet carries a spore. To 

 save confusion, a large num- 

 ber of spores are omitted from 

 B 



K "") 



*&. ;,^^_ \^J 



the branchlets in the illus- 

 tration, and the branches 

 growing from the stem both 

 before and behind are for the 

 same reason left out. At B 

 a tip of a single branch is 

 shown further enlarged to 

 four hundred diameters. The 



spores in the Poppy fungus are unusually large and numerous : an 

 infected plant will throw off many millions of such spores. All the 

 putrefactive spawn of this fungus is inside the host-plant ; cure, 

 therefore, is difficult. This disease, like every other plant. disease, is 

 always at its worst in ill-kept places where red field Poppies are 

 abundant. Field Poppies are often sown with unclean corn. As 

 prevention is better than cure, all we can advise is, buy the best and 

 cleanest garden and field seeds, cultivate in the best way, and look 

 out for arid burn, or deeply bury as soon as detected, all disease- 

 stricken plants, whether wild or cultivated. When diseased plants 

 of any sort are left to decay on the refuse-heap, it is the most certain 

 way of propagating a plant disease for the next year. 



X-fOO- 



FUNGUS OF POPPY DISEASE 

 Peronospora arborescens 



Diseases of Violets. Violets are subject to fungoid diseases, 

 both in spring and autumn. The disease of autumn is caused by the 

 brown Pucdnia viola, allied to the P. graminis of Corn and to the 

 P. malvacearum of Hollyhocks and various malvaceous plants. The 

 Pucdnia of Violets has its yellowish or orange-coloured stage ; it is 

 then known as Trichobasis, or Uredo violarum. In spring and early 

 summer Violets are often badly affected by a fungus named sEcidium 



432 



