Downy mildew of lettuce, caused by the fungus Bremia lactucae, can cause considerable damage especially to early spring and late fall crops in coastal areas. It is favored by cool, moist weather and may occasionally cause economic damage in the Imperial Valley during the winter lettuce season. Trials were initiated in the summer and fall of 1976 to compare new systemic fungicides from Ciba Geigy with commonly used materials.