Associate Professor Kansas State University Parsons, Kansas
Abstract: Throughout Kansas, invasive grass species are taking over native prairie and grasslands, thus reducing the quantity and quality of native grasses for ruminants to graze. Ultimately, complete eradication is unlikely for some invasive species, but working to manage population expansion is important to ecosystems. Sericea lespedeza encompasses approximately 2.2 million ha of the United States grazing land and continues to encroach on quality grazeland. The objective of this study was to identify if spraying a molasses mixture at four different levels would decrease the infestation of a noxious weed, Sericea lespedeza, in tallgrass native range pastures grazed during the summer. Steers (n=281; 291 ± 5 kg) were randomly assigned to one of 8 tallgrass native range pastures to graze between May and August based on a predetermined sort order through chute. Within each pasture, four locations were identified to have heavy S. lespedeza infestation and were randomly assigned to one of four treatments. Treatments were applied weekly at equal rates of 468 L/ha and consisted of 4 treatments: control (CON: water only); 12.5% (v/v) molasses concentrated spray (12.5M); 25% (v/v) molasses concentrated spray (25M); and 50% (v/v) molasses concentrated spray (50M). Plant counts of S. lespedeza were conducted on permanent transects within spray quadrants and occurred on 0, 30, 60, and 90 d of cattle grazing pastures. Steers (n = 29; 3-4 per pasture, equal to 10% of total steers per pasture) were fitted with GPS and activity tracking ear tags and monitored for location to determine proportion of time spent in sprayed areas and within the immediate vicinity of sprayed area. Sericea lespedeza count data was analyzed using PROC GLIMMIX in SAS 9.4 with pasture as experimental unit. Animal grazing data was analyzed using PROC GLIMMIX in SAS 9.4 with animal within pasture as experimental unit. Sericea lespedeza numbers were lower at the end of grazing in the subplots that were sprayed with molasses as compared to CON (P = 0.003). There was a quadratic effect (P = 0.01) where 12M had a more pronounced effect on S. lespedeza than CON and 50M. Spraying infested areas did not stop the growth of S. lespedeza as there were more plants in August as compared to May (P < 0.01). There was no difference in time spent grazing in the sprayed areas (P = 0.31); however, the steers spent more time grazing in the areas closest to 12.5M as compared to 50M with 25M being intermediate (P = 0.01). Overall, in this first year of data collection, it appeared that spraying with 12.5% molasses (v/v) will entice cattle to spend more time in an area with undesirable plant populations, ultimately resulting in a less pronounced growth of plants.
