ANNUAL REPORT, 1947-48 45 



DDT Residues on Grass Beneath Elms Sprayed for Elm Bark Beetles. (W. B. 



Becker and A. F. Spelman.*) The Feed and Fertilizer Regulatory Service co- 

 operated by making DDT analyses of grass collected from pasture areas on which 

 the spray dripped and drifted from elms sprayed with DDT emulsion from high- 

 powered hydraulic sprayers. DDT (technical grade) was used at the rates of 

 16 and 8 pounds per 100 gallons, and as much as 25 gallons of spray was applied 

 per tree. The residue was determined by the total chlorine method and based on 

 the oven-dry weight of the grass. 



August 15 application (soon after removal of cut hay); After 4 days with 0.52 

 inches of rainfall, the residue from the 16-pound application was 6,885 p.p.m. 

 DDT; from the 8-pound application, 4,035 p.p.m. After 68 days with 4.55 

 inches rainfall, the corresponding residues were 1,658 and 851 p.p.m. 



April 25 application: After 96 days with 11.63 inches rainfall, the residue from 

 the 16-pound application was 43 p.p.m. DDT; from the 8-pound application, 

 45 to 50 p.p.m. 



Such high DDT residues would seem to be undesirable and possibly hazardous 

 where food for man or animals is involved. More detailed studies are in progress. 



FEED AND FERTILIZER CONTROL SERVICES 

 John W. Kuzmeski in Charge 



The feed, fertilizer and milk testing laws are administered as one service and 

 the operation of each, with the exception of the milk testing law, is reported in 

 annual bulletins. 



Under the milk testing law 4,915 pieces of Babcock glassware were calibrated 

 and 177 certificates of proficiency in testing were issued. All milk depots and 

 milk inspection laboratories in the Commonwealth were visited at least once to 

 check apparatus and general conduct of the work. 



In addition to the regulatory work the Feed and Fertilizer Control labora- 

 tories have examined feeds, fertilizers, and other agricultural materials for 

 citizens of the Commonwealth without charge whenever the results were con- 

 sidered of interest to the general public or to the Control Services. 



Considerable work has been done on research projects in cooperation with 

 other departments of the University and Experiment Station. The results of 

 such work are reported by the departments originating the projects. 



DEPARTMENT OF FLORICULTURE 

 Clark L. Thayer in Charge 



Breeding Snapdragons for Variety Improvement and Disease Resistance. 



(Harold E. White, Waltham.) A dark pink flowered strain of Helen Tobin has 

 been developed into a pure inbred line and seed has been distributed to local 

 growers. The original Helen Tobin, which is a light pink variety, has been 

 reported by several florists to be a good spring blooming variety to follow chrys- 

 anthemums. This variety, since its first introduction, has been used very suc- 

 cessfully for an outdoor crop by a florist near Tampa, Florida; this year the firm 

 plans to grow a crop of 8,000 to 10,000 plants. George J. Ball, Inc., West Chicago, 

 Illinois, and other commercial growers are using Helen Tobin as breeding stock 

 because it is an excellent seed producer and has other desirable characters. 



* Senior chemist, Feed and Fertilizer Regulatory Service. 



