From 1919 to 1922 inclusive, the San Jose scale caused more damage in southern Illinois than in any equal period since it was first established in this state. Following the work of Dr. Forbes and his assistants in 1900, 1901, and 1902, liquid lime-sulfur had been considered the standard remedy for San Jose scale control. Previous to 1919, it had not failed to give a satisfactory commercial control where thoroughly applied at dilutions of from 1 to 6, to 1 to 8. During 1920 and 1921, some of the best and most careful orchardists in southern Illinois lost trees from scale although these trees had been thoroughly sprayed with lime sulfur. In some instances the failure to control with it could be accounted for by the fact that the trees had been poorly sprayed, or an insufficient amount of material had been applied. In other cases, however, the applications had been made as thoroughly as seemed possible and enough material had been put on to cover the trees thoroughly. During the years mentioned above, a series of mild winters following warm late falls had allowed the scale to increase at an unusual rate, so that trees having a small amount of live scale remaining upon them in spring were heavily infested by fall. Because of the failure of lime sulfur to give a satisfactory control of scale, a series of experiments to test other scalecides was made by the Natural History Survey during the winter of 1922.published or submitted for publicationis peer reviewe
