The Beneficial and Injurious Influences of Fungi. 193 



totaling, with some of the minor diseases, to over £50,000,000 

 per annum. The Prussian statistics for the year 1891 estimate 

 the injuries to corn crops alone, to be over £20,000,000. 



No statistics are available for Britain, France, Russia, 

 Canada, Australia or South America. 



These figures will suffice to emphasize the destructive 

 effect of plant diseases when not under control. 



One of the most destructive of the parasitic fungi is the 

 Rust of wheat (Puccinia graminis) which affects the leaves 

 so much as to lessen the vitality of the plant, thereby reducing 

 considerably the quality and quantity of the corn produced. 



This fungus pest has been known for thousands of years ; 

 many of the ancient writers refer to it, Pliny several times 

 mentions it, and in one passage calls it ' the greatest pest of 

 the crops.' They tried to account for its presence in various 

 ways such as evil spirits, * the weather, lightning, blight, wrath of 

 the Almighty, etc. Virgil suspected the proximity of Juniper 

 bushes to be the cause when he says : 



' From Juniper unwholesome dews distil, 

 That blast the sooty corn, the withering herbage kill.' 



Pastoral X. 



The Romans held on April 25th in each year a festival called 

 Rubigalia to implore their deities to ward off the Rust disease 

 and to protect their crops from this fungus pest. 



The study of the life history of this Rust disease has been 

 for many years pursued by plant pathologists on account of 

 its importance economically, and of its great interest biologically 

 as it passes through three well-defined stages in its existence, 

 each of which was formerly considered a separate entity. 



The first appears in spring on the leaves of Barberry and 

 shrubs of that natural order in the form of yellow cluster 

 cups producing spores (aecidiospores) which, when carried by 

 wind and other agencies, infect the young wheat plants, 

 causing them in a few weeks to have a rusty appearance due 

 to small bright orange patches filled with power (uredospores) 

 and the infection of the surrounding plants quickly takes 

 place. From these same patches, a few weeks later, another 

 set of spores arise, purple black in colour (teleutospores) which 

 lie dormant all the winter and infect the Barberry leaves in 

 spring. 



For two or three centuries past it was noticed that the 

 presence of the Barberry had an injurious effect upon the wheat 

 crops, and a law was passed in 1755 for the extirpation of all 

 Barberry bushes in the province of Massachusetts in America, 



* . . . The foul fiend Flibbertigibbet mildews the white wheat. 



King Lear, Act III., Scene IV. 



1917 June 1. 



