The minimum times required for killing the chrysanthemum eelworm (Aphelenchoides ritzema‐bosi, Schwartz) in water, over a range of temperatures have been determined and the technique employed is described. A temperature of 115° F. for 5 min. is preferable to the usual standard treatment of 110° F. for 20–30 min. and enables stools to be treated with less retardation of cuttings or death of stools, with a consequent great increase in the number of cuttings obtained. The results are of special value in connexion with varieties susceptible to damage by the hot water trea