Extension Work in Plant Pathology, 1923 3 



Field, storage, and transit losses must be made up in part by in- 

 creased market prices, so that the consumer shares with the farmer 

 in payment of the annual toll exacted by disease. 



AIM OF EXTENSION WORK IN PLANT PATHOLOGY 



Realization of this serious annual loss due to plant diseases has 

 resulted in the growth of extension work in plant pathology. The 

 aim of the work is to increase the efficiency of production, maintain 

 high quality of plant products, and prevent wastage in storage, 

 transit, and at the market. 



Fig. 2. — Nail-head spot of tomato often makes fruit unmarketable, or places it in a 

 low grade. (From series prepared by Link and Gardner.) 



NATURE OF CONTROL MEASURES ADVOCATED. 



A study of the annual reports of extension agents shows that three 

 main type- of work enter into the plant-pathology extension 

 program : 



(1) Bringing into more universal use measures that have long been known 

 to farmers in a general way, but which need urging to overcome the inertia 

 which prevents general adoption. Sometimes such measures need modifica- 

 tion to make them locally effective or within the means of the average man. 



( 2 ) Improvement of old control methods. As a result of the discovery of 

 new facts through research work in plant pathlogy. control methods are con- 

 stantly being improved. New information concerning the life history of the 

 causal organisms may make this possible. More effective chemicals may be 

 brought into use for treating soils or seeds or for the preparation of sprays. 

 The development of new machinery sometimes makes a method more effective 

 or easier of application, and perhaps puts it within the reach of more people. 



(3) Introduction of entirely new control measures resulting from recent 

 discoveries by research workers. Field and laboratory investigations here 

 and there result in the discovery of fundamental facts concerning a disease, 



