Extension Work in Plant Pathology, 1923 11 



After the seed was sown it Was necessary to take records on a 

 sufficiently large scale to convince growers who had not yet adopted 

 the method that copper-carbonate treatment paid. During 1923 

 172 fields were examined in six counties. Records were taken on 

 stand and the percentage of smut was determined in the case of 

 grain grown from untreated seed and from seed that was treated 

 with copper carbonate, formaldehyde, and bluestone. Records of 

 this kind were brought to the attention of farmers. As a result of 

 these activities it is estimated that approximately 1,500,000 acres 

 of the 1923-21 wheat crop were sown with treated grain. Similar 

 work is under way in other States where bunt is a serious factor. 



SWEET POTATOES 



Treatment of sweet-potato seed eliminated black-rot on certain 

 Kansas farms and materially increased the yield per acre. In dis- 

 cussing this work, E. A. Stokdyk, extension plant pathologist, called 

 attention to the fact that seed-treatment activity gave an avenue of 

 approach for other lines of extension work. 



CABBAGE 



Seed treatment at the commercial seed house before distribution 

 of cabbage seed stocks will probably become more common as time 

 goes on. In Xew York three cabbage-seed producers were so 

 strongly impressed with the results obtained by use of the hot-water 

 method, as developed by cooperation between plant pathologists of 

 the State and Federal Government, that they planned to treat most 

 of the seed to be put on the market for 1924. If this practice could 

 be made general, black-leg would be practically eliminated. 



SPRAYING AND DUSTING 



RELATION OF EXTENSION WOIIK TO SPKAYING AND DUSTING 



Farmers probably needed more assistance with spraying and dust- 

 ing than with any other practice in disease control. This is due 

 to the fact that if these measures are to be effective and profitable 

 the fungicide must be prepared accurately and applied correctly 

 within a definite and limited period, a period which depends on such 

 matters as condition of fungous and insect pests, state of develop- 

 ment of the plant, and variations in weather. The fact that con- 

 ditions that influence the time of application and the choice of 

 spray mixture to be used are likely to differ somewhat each season, 

 necessitates constant watchfulness on the part of plant pathologists 

 and entomologists to determine the appropriate sprays and the 

 critical times for their application. In 1923, in order that farmers 

 might have full benefit of such observations, the extension program 

 was usually developed along the following lines : 



(1) Education of groioers in fundamentals of disease control. — 

 This was an important feature of the work done by the extension 

 pathologist in several States. E. C. Sherwood, extension plant 

 pathologist of West Virginia, reported as follows : 



Addresses on plant diseases at general meetings were usually made in three 

 sections. In the first section the nature and cause of plant diseases were 

 explained in nontechnical language designed for the purpose. The difference 

 between the cause of disease and its manifestation was brought out and 



