Matt Sousek

Biomass production of herbaceous energy crops in the United States: field trial results and yield potential maps from the multiyear regional feedstock partnership

Current knowledge of yield potential and best agronomic management practices for perennial bioenergy grasses is primarily derived from small‐scale and short‐term studies, yet these studies inform policy at the national scale. In an effort to learn more about how bioenergy grasses perform across multiple locations and years, the U.S. Department of Energy (US DOE)/Sun Grant Initiative Regional Feedstock Partnership was initiated in 2008. The objectives of the Feedstock Partnership were to (1) provide a wide range of information for feedstock selection (species choice) and management practice options for a variety of regions and (2) develop national maps of potential feedstock yield for each of the herbaceous species evaluated. The Feedstock Partnership expands our previous understanding of the bioenergy potential of switchgrass, Miscanthus, sorghum, energycane, and prairie mixtures on Conservation Reserve Program land by conducting long‐term, replicated trials of each species at diverse environments in the U.S. Trials were initiated between 2008 and 2010 and completed between 2012 and 2015 depending on species. Field‐scale plots were utilized for switchgrass and Conservation Reserve Program trials to use traditional agricultural machinery. This is important as we know that the smaller scale studies often overestimated yield potential of some of these species. Insufficient vegetative propagules of energycane and Miscanthus prohibited farm‐scale trials of these species. The Feedstock Partnership studies also confirmed that environmental differences across years and across sites had a large impact on biomass production. Nitrogen application had variable effects across feedstocks, but some nitrogen fertilizer generally had a positive effect. National yield potential maps were developed using PRISM‐ELM for each species in the Feedstock Partnership. This manuscript, with the accompanying supplemental data, will be useful in making decisions about feedstock selection as well as agronomic practices across a wide region of the country.

Weed Control and Turf Safety of Single and Sequential Applications of Herbicides Over Spring Seedings

Weed control is important during establishment of cool-season grasses, especially when seeded in spring near summer annual weed germination. Our objectives were to determine (i) turf safety and weed control from sequential applications of newly-released herbicides on tall fescue at three seeding dates (May, June, July) and (ii) turf safety and weed control from newly-released herbicides applied at seeding or shortly after emergence of spring-seeded Kentucky bluegrass or tall fescue. No herbicides tested negatively affected turfgrass establishment and usually improved turf establishment by reducing weed competition. Mesotrione consistently provided effective weed control and turf cover from either single or sequential applications over different locations, years, seeding dates, and turf species. Quinclorac or siduron applied as single or sequential applications or quinclorac+carfentrazone as a single application provided effective weed control and turf cover depending on seeding date and application regime. Although spring seeding can be achieved with high maintenance, it is strongly recommended to seed cool season grasses at the optimal time from late summer to early fall.

Seasonal Timing of Glyphosate Application Influences Control of Poa trivialis

Rough bluegrass (RBG; Poa trivialis L.) is a perennial cool-season turfgrass and a problematic weed in coolseason turf due to suboptimal color, invasive stoloniferous growth, and sensitivity to heat and drought. Naturalized populations spread vegetatively during routine aeration and from contamination in seed lots (Reicher et al., 2011). Bispyribac-sodium (Velocity) is the only product currently labeled for selective RBG removal in cool-season turf and is effective, but it can damage desirable species (McCullough and Hart, 2011) and is only labeled for sod-farm and golfcourse use. Nonselective herbicides are often the only option for RBG control in home lawns, but it is unclear if efficacy varies with seasonal application timing, like RBG response to bispyribac-sodium (McCullough and Hart, 2011). Rough bluegrass persistence is anecdotally reported after latesummer glyphosate application. Adkins and Barnes (2013) observed better Kentucky bluegrass (Poa pratensis L.) control with spring treatments of imazapic plus glyphosate, but tall fescue (Festuca arundinacea Schreb.) control was better following summer applications. Therefore, our objective was to determine if the seasonal timing of glyphosate application influences RBG control.

Speedzone has Potential for Postemergence Goosegrass Control in Perennial Ryegrass and Creeping Bentgrass

Goosegrass (Eleusine indica [L.] Gaertn.) is a C4 summer annual distributed throughout the transition zone and can be problematic in sports fields and lawns, but more often is problematic in golf course greens and tees where preemergence (PRE) herbicides are rarely used because of frequent reseeding in-season. The postemergence (POST) herbicides monosodium methanearsonate (MSMA), fenoxaprop-ethyl, or sulfentrazone are commonly used to control goosegrass on golf courses. However, MSMA has recently lost most of its labeled uses (EPA, 2013), while fenoxaprop-ethyl is restricted from use at mowing heights less than 0.25 inch (Anonymous, 2005) and sulfentrazone is restricted from use on golf course greens or tees (Anonymous, 2012). In July 2011, control of goosegrass was reported when Speedzone was applied to golf course tees to control summer annual broadleaves in Omaha, NE (J. Calentine, personal communication, 2011). This was further reported anecdotally at multiple sites in Nebraska later that summer. Therefore, we began our studies in 2012 with the objectives of confirming if Speedzone has potential for goosegrass control and if so, what application rates and intervals are most effective while still safe on cool-season turfgrasses. The experiment was conducted in 2012 and 2013 at the John Seaton Anderson Turf Research Facility near Mead, NE. In October of 2011, sand-based thinly cut sod of Kentucky bluegrass (Poa pratensis) and perennial ryegrass (Lolium perenne) from a tee on a local goosegrass-infested golf course was moved to the experimental site, distributed evenly and tilled into the top inch of soil. Soil type on the experimental area was Tomek silty clay loam (fine, montmorillonitic, mesic Typic Argiudoll) with pH 6.9 and 2.7% organic matter. A perennial ryegrass blend was seeded at 3 lbs/1000 sq ft in April 2012 to establish a thin turf cover. Following establishment, the area was irrigated to prevent water stress, mowed at 0.625 inch, and not fertilized to minimize turf competition with goosegrass. Before goosegrass germination and initiating treatments, glyphosate was applied Published in Applied Turfgrass Science DOI 10.2134/ATS-2014-0025-BR

Fall or Late Winter Applications of Preemergence Herbicides Rarely Provide Season-long Control of Crabgrass ( Digitaria spp) in Nebraska

Fall and late winter applications of preemergence herbicides (PREs) for crabgrass control have been evaluated in Illinois (Fermanian and Haley, 1994), Pennsylvania (Reicher et al., 2011), Indiana (Reicher et al., 2011; Reicher and Throssell, 1993), and Maryland (Dernoeden, 1993). The authors generally concluded that fall and late winter applications provide season-long control with higher application rates in areas with low/moderate crabgrass pressure. Many of these studies used older formulations of current active ingredients. None of these studies were located in the northwest edge of the transition zone where cool-season grasses dominate because of winter survival, but summer temperature extremes can thin even irrigated cool-season stands. Our objective was to determine if fall or late winter applications of PREs can provide season-long control of crabgrass in Nebraska.