At the time of trial implantation (11 January 1996), Fusilade® (fluazifop-P-butyl) was a registered herbicide used for the control of grasses in commercial eucalypt plantations. However, concern was expressed about young eucalypt seedling phytotoxicity from “over the top” spraying with Fusilade®, especially under hot and humid conditions. This was tested in a nursery trial using Eucalyptus grandis clonal cuttings (GC784) and Eucalyptus nitens seedlings. Fusilade® was applied at 3 and 6 L ha-1, 33 days after planting and at 4 and 8 L ha-1, 54 days after planting, at three different times (08:30, 10:00 and 12:30) during the morning. The lower rates of herbicide application and the dates on which they were applied coincided with the development of grass vegetation, but before it became competitive. Assessments of root collar diameter, height and dry above-ground biomass showed no significant differences between the different treatments.