

UNITED STATES 



DEPARTMENT of AGRICULTURE 



DEPARTMENT CIRCULAR 329 



Washington, D. C. November, 1924 



EXTENSION WORK 

 IN PLANT PATHOLOGY. 1923 



FRED C. MEIER. 



Extension Plant Pathologist, Office of Cooperative Extension Work and 

 Bureau of Plant Industry Cooperating 



Page 

 Relation of plant diseases to crop 



production 1 



Aim of extension work in plant 



pathology 3 



Nature of control measures advo- 

 cated 3 



Leadership of extension specialists-- 5 



Extension conferences 6 



CONTENTS 



Page 



Outstanding activities : 



National program of work 6 



Planting disease-resistant varie- 

 ties 7 



Seed disinfection 8 



Spraying and dusting 11 



Selecting seed free from disease- 15 



Results ._ 19 



Conclusion 19 



Appendix 20 



RELATION OF PLANT DISEASES TO CROP PRODUCTION 



With the growth of our agriculture, new plant diseases are intro- 

 duced and abundant opportunity is given for their development and 

 dissemination. Extensive cultivation of any one crop in a region 

 usually favors the increase of plant parasites. Frequently, by the 

 time a crop reaches a place of importance in a community, the 

 presence of one or more diseases has introduced an unwelcome ele- 

 ment of uncertainty in plans for production. 



Decreases of yield due to disease may be very serious and often 

 bring the individual farmer face to face with a difficult economic 

 problem (fig. 1). Tt is estimated that, in the case of siN crops, the 

 reduction in yield from disease during 1922 was a- follows: Wheat. 

 83.795.000 bushels: cotton. 417.000 bales: corn. 1s7.5i2T.000 bushels: 

 potatoes. 120.943.000 bushels: apples. 59,120,000 bushels: and 

 peaches. 13.06S.000 bushels. 1 Because of higher prices obtained for 

 the remainder, such reductions in yield may not result in correspond- 

 ing reduction^ in the value of the total crop, yet they do represent 

 actual los-es to the individuals who suffered them. 



-Supplement 30, The Plant l»is^a-e Reporter. Plant Disease Surrey, t". S. Department 



of Agriculture. 



8938—24 1 



