Rate of spotted knapweed reinvasion in relation to Picloram, fertilizer and defoliation treatments was examined in this clipping study west of Bozeman, Montana from 1994 through 1997. Sixteen chemical treatments (4 picolram rates, and 4 fertilizer rates) were applied to 4 by 4 m plots; within each plot one of six defoliation treatments (no defoliation, spring, summer, fall, alternating fall/spring, and spring-summer-and fall) was applied to 1x1 m subplots. There were 4 replications at 2 sites classified as Idaho fescue and bluebunch wheatgrass habitat types. All grass plants within the subplot were hand-clipped to remove 60% of present standing crop present at each clipping. In August of 1997, juvenile and total spotted knapweed plants (plants m-2) were counted and percent cover for spotted knapweed, all grass species, litter and bare ground was estimated with 0.2 x 0.5 m frames within each sub-plot prior to standing crop harvest. Peak standing crop was clipped in a 0.5 m² frame randomly located within each plot in August of the 1997.
Citations and enhanced abstracts for journals articles and documents focused on rangeland ecology and management. RSIS is a collaboration between Montana State University, University of Idaho, and University of Wyoming.