Intensive cattle grazing in May and June reduced yellow starthistle plant size, summer and fall canopy size, and seed production in the first year of a 3-year, northern California study. Combining grazing and herbicide applications caused large reductions. Abundant late rains favored yellow starthistle growth.

The authors thank the Salvesons and O'Connells for use of their land, assistance, and hospitality; Jack and Nancy Henderson of Live Wire Products, Marysville for assistance in fencing design and construction at the Salveson Ranch; Jim Pratt for help in Colusa County; John Roncoroni, Staff Research Assistant, Botany Extension, for herbicide applications; and John Menke, Professor, Department of Agronomy and Range Science, UC Davis, for advice. This project is supported by a grant from UC/IPM.