INTEGRATED MANAGEMENT STRATEGIES TO REDUCE WEED POPULATIONS AND IMPROVE GRAZED PASTURE PRODUCTIVITY
Lyons,* J.K.1; Green, J.D.2; Sears, B.G.3; Tolson, J.A.4; Yankey, T.R.51Extension Agent, Kentucky Cooperative Extension, Monroe County, Tompkinsville, KY, 42167
2Extension Specialist, Kentucky Cooperative Extension, Lexington, KY, 40546
3Extension Agent, Kentucky Cooperative Extension, Madison County, Richmond, KY, 40475
4Graduate Assistant, Kentucky Cooperative Extension, Lexington, KY, 40546
5Extension Agent, Kentucky Cooperative Extension, Anderson County, Lawrenceburg, KY, 40342
Abstract:
Problematic weeds such as tall ironweed (Vernonia altissima) and horsenettle (Solanum carolinense) have been increasing in pastures during the past several years as livestock grazing has intensified in Kentucky. Field studies were conducted on grazed pastures on farms near Tompkinsville, Lawrenceburg and Richmond, Kentucky during 2008-2010 to evaluate whether the management practices of mowing, herbicide, and added fertility can reduce weed populations and improve pasture productivity. Each individual management strategy plus combinations were evaluated using a three-way factorial experimental design. Mowing was performed in July, herbicide treatments in mid-August, and added fertility in September. Weed populations were measured using 10 ft2 quadrants in 2008 and during the following two seasons. Three subsamples per plot were also harvested each year to measure desirable forage yield and weed biomass produced. Harvested samples were separated into forage grasses, clover, and weeds present. Mowing alone or in combination with fertility had no effect in reducing weed populations and did not significantly change the quantity of forage or weed biomass produced. All treatments that included a herbicide application provided 85 to 94% reduction in tall ironweed 1 year after treatment. Other weed species such as common ragweed, goldenrod and marshelder populations were reduced approximately 100% and horsenettle was reduced 60%. Although clover stands were reduced by herbicide treatments, yield of desirable forage grasses increased at two of the three locations and total weed biomass was reduced at all locations. Added fertility increased yield of desirable forage species and had no effect on weed biomass.