PROBLEMS IN PREVENTING 

 PLANT-DISEASE EPIDEMICS 



E. C. Stakman ^ 



Plant disease epidemics, outbreaks of insect pests, bad weather, and human 

 ignorance are the greatest obstacles to assured food supplies for the peoples 

 of the world. Throughout recorded history, and probably before that, man 

 has been confronted at certain times and in certain places with the specters 

 of hunger and famine because of devastating plant diseases, destructive in- 

 sects, droughts and floods, searing heat, and killing cold. This is evident from 

 legends of the remote past, from historical records, and from recent experi- 

 ences. 



When man progressed from a food gatherer to a food producer, he alleviated 

 some problems of human subsistence but he also created many new ones. 

 He not only transformed rice, wheat, barley, maize, and millet from grass to 

 grain but he also transformed the lands on which they were grown. He re- 

 moved the natural vegetation by clearing forests, ploughing grasslands, drain- 

 ing swamps, and irrigating deserts. And he planted one kind of plant in dense 

 stands on lands where there had been sparser populations of many kinds of 

 native plants. This concentration of homogeneous plant populations created 

 the same kind of problems as the concentration of human populations in 

 cities; it tended to aggravate the problems of diseases and pests. Plant 

 public health became a problem, just as human public health became a prob- 

 lem when people crowded together in cities. 



Man had to become a botanist in order to become civilized. As M. D. C. 

 Crawford said, "Civilization is, as it were, a second flowering of barley, 

 wheat, rice, and Indian corn." Although the concept of civilization usually 

 includes more than the improvement and cultivation of plants, there could 

 be no civilization without them, because man could not exist without them. 



^ The writer is indebted to Laura M. Hamilton for assistance in the preparation 

 of the material on epidemiology of stem rust. 



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