52 DISEASES OF CULTIVATED PLANTS 



From estimates furnished by the United States, Germany, 

 Australia, etc., it is calculated that the annual loss on 

 cultivated crops, caused by pronounced diseases or epidemics, 

 ranges between ^i 50,000,000 and ^200,000,000. Pro- 

 bably double this amount would be a more accurate estimate 

 if we take into consideration the constant loss occasioned on 

 a scale too small to be recognised in preparing estimates. 



Much of this loss could undoubtedly be prevented, but 

 the methods adopted would require to be general and 

 compulsory; in fact it is a work for the state and not for 

 the individual to undertake. 



The following figures will convince that the above state- 

 ments are in reality more than suppositions, without any 

 basis of fact. 



The coffee-leaf disease in Ceylon caused a total loss 

 amounting at the least estimate to ^17,000,000. 



In the United States, the following official statements have 

 been made. 



Wheat rust in one year amounted to $15,000,000. 



Loose smut in oats $18,000,000, annually. 



Bitter rot of apples, $10,000,000 annually. 



Grape disease in two years amounted to $20,000,000. 



A careful estimate furnished by the Prussian Statistics 

 Bureau showed that in one year the loss from rust of cereals 

 amounted to just over ^20,000,000. 



Australia experienced a dead loss of two and a half 

 million pounds sterling due to wheat rust in a single 

 season. 



All the above represent loss due entirely to fungus 

 diseases. The loss caused by insects is quite equal or even 

 greater in amount. 



FUNGICIDES 



The term fungicide is given to the various solutions and 

 powders applied to cultivated plants for the purpose of 

 checking diseases caused by parasitic fungi. 



A fungicide to be of practical use should possess the 

 following points : 



(1) Destroy the parasite without injuring the host-plant. 



(2) Easy to prepare and to apply. 



(3) Cost moderate. 



