Controlling forage weed species detrimental to livestock production

• Main Author: Russell, David Pierce
• Other Authors: John D. Byrd
• Format: Others
• Language: en
• Published: MSSTATE 2017
• Subjects: Plant and Soil Sciences
• Online Access: http://sun.library.msstate.edu/ETD-db/theses/available/etd-10242017-093433/

Among the vast diversity of plants in the mid-South to which grazing livestock are exposed, there is a need to address certain species that are potentially harmful to livestock health and production. Field and greenhouse experiments were conducted on endophyte-infected tall fescue [<i>Schedonorus arundinaceus</i> (Schreb.) Dumort = <i>Lolium arundinaceum</i> (Schreb.) Darbysh.], a cool-season perennial forage, and perilla mint, (<i>Perilla frutescens</i> (L.) Britton) an herbaceous annual, to determine management techniques and control measures for healthier pasture and livestock systems. When seedheads reached maturity, spring and autumn glyphosate applications at 1.68 kg ae ha^-1, coupled with autumn tillage and summer and winter cover crops effectively reduced tall fescue coverage to < 27% by 10 months after initial treatment (MAT) following a single year of management. If seedhead maturity is inhibited prior to first glyphosate application, tall fescue was reduced to <1% coverage 10 MAT. Despite seedhead suppression, at least 78% increase in coverage occurred in 24 months from remnant populations suggesting two years of renovation is required. Forage soybeans proved to be a valuable cover crop that maintained nutritive quality and mean dry matter yields of 5487 kg ha^-1 across two years. Tall fescue seedheads were suppressed below 14% coverage (> 68% visual control) by nicosulfuron + metsulfuron (20 + 5 and 40 +11 g ai ha^-1), imazapic (26 and 53 g ai ha^-1), and sulfosulfuron (53 g ai ha^-1) at 90 DAT. Reduction in forage heights may be expected, but was not consistently reduced when compared to untreated plots across locations. To control perilla mint, postemergence applications of aminocyclopyrachlor blends, glyphosate, picloram + 2,4-D, aminopyralid + 2,4-D, and 2,4-D alone provided superior control when applied prior to the plants reproductive growth stage. Picloram + 2,4-D also provided in-field soil residual activity and the most effective preemergence control, followed by aminocyclopyrachlor + chlorsulfuron, pendimethalin, and aminopyralid + 2,4-D for at least 141 DAT. Seed from weedy populations in north Mississippi tend to germinate in a range of night/day soil temperatures from 10/15 C to 25/30 C. Therefore, effective preemergence treatments should be applied by mid- to late- February in this region.