THE CORN SMUTS AND THEIR 

 PROPAGATION 



By T. JOHNSON, D.Sc. 



Professor of Botany in the Royal College of Science, Dublin 



A few years ago the reading public was startled by the state- 

 ment that if the population of the world continued to increase 

 at the present rate there would come a time when a famine 

 would occur owing to a shortage in the supply of corn. This 

 shortage would be due to the fact that as the corn plant cannot 

 be grown without nitrogenous food materials in its mineral 

 food supply, and that as the amount of nitrogenous matter in 

 the soil is limited, the increasing nations, using more and more 

 of the earth's surface for their corn crops, would in time reach 

 the limit of supply. 



I do not propose to stop to consider the successful steps now 

 being taken to utilise the atmospheric nitrogen to supplement 

 the soil's supply, but to devote attention to the advance made 

 by botanists in the detection and prevention of the loss of 

 nitrogenous matter already gained. Probably as long as corn 

 has been grown a cause of loss of the nitrogenous food material 

 in the grain of corn, gained by the corn plant's metabolism from 

 the nitrogenous food material in the soil and stored in the grain 

 in a form available for utilisation by man, has been at work. 

 I mean the loss due to the diseases of the cereals we now 

 recognise as caused by certain fungal pests known as " smut "" 

 and " rust." 



The loss inflicted by these two scourges in the corn-growing 

 countries of the world is enormous, and yet it is only within the 

 last two generations that our knowledge of their nature has 

 become at all accurate. I shall in this paper confine my 

 remarks almost entirely to the smut disease. 



My own practical (as distinguished from scholastic) interest 

 in the smut question was first aroused by the sight of the oat 

 crops in the west of Ireland, where, in the islands on the 

 seaboard, the crops were, in many places, in a deplorable state 



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