Both sellers and users of farm seeds in Iowa are alert to the menace that lies in weed seeds and other impurities and are striving to comply with the state seed laws and to prevent the introduction and spread of injurious weeds. That is indicated in the continually increasing number of seed samples submitted for testing to the Botany Section of the Iowa Agricultural Experiment Station. In the eight-year period ending June 30, 1921, the average number of samples tested was 1,060 annually, as against less than half that number in the previous corresponding period.
Pammel, L. H. and King, C. M.
"Seed analyses of 1913 to 1921,"
Bulletin: Vol. 17
, Article 1.
Available at: https://lib.dr.iastate.edu/bulletin/vol17/iss203/1