220 TEXT-BOOK OF FUNGI 



to distant localities, even to a new continent, where 



the fungus was not known to exist previous to the 



introduction of its host-plant. 

 2. Diseases that spread from an area known to be 



infected, to adjoining areas hitherto free from 



disease. 



Instances falling under No. i will first be given. 

 Previous to the introduction of wheat into Australia, the 

 wheat rust fungus (Puccinia gramwis) was unknown in 

 that country, but almost at once, after the cultivation of 

 wheat commenced, rust appeared in full force ; and at the 

 present day wheat in Australia suffers as much from rust 

 as in any other part of the world. 



The Hollyhock, imported to Europe from Chile, was 

 followed by its natural enemy, Hollyhock rust (Puccinia 

 malvacearum\ which not only at one time threatened to 

 exterminate this plant in Europe, but has also attacked all 

 European wild species of plants allied to the Hollyhock. 



Quite recently diseased specimens of French beans were 

 sent to Kew for investigation from the Botanic Station, 

 Mairobi, British East Africa. It was stated that the plants 

 had been grown there for the first time, and promised to 

 yield a good crop, when they were suddenly all destroyed 

 by some disease. On investigation it proved that both 

 the leaves and fruit were attacked by the same kind of 

 fungus respectively, from which they so frequently succumb 

 at home; the parasite on the leaves being Uromyces 

 phaseoli, that on the fruit was Colletotrichum lindemuthi- 

 anum. Lucerne suffers in America, Australia, and the 

 Transvaal from the same kind of fungus that destroys it 

 in Europe. Maize smut is now common in Europe. 

 Seedlings of Verbena raised in Brisbane have been de- 





