Crop, Forage and Turfgrass Management最新文献

Planting date, row configuration, and seeding rate are three critical factors in obtaining maximum soybean [Glycine max (L.) Merr.] grain yield and can vary based on soil texture. Therefore, two studies were conducted at the Delta Research and Extension Center in Stoneville, MS. The first study was conducted from 2019 to 2021 and sought to determine the effects of planting date (optimal and delayed 21 days), and row configuration (single-, twin-, and triple-row) on soybean growth, development, and grain yield. The second study was conducted in 2021 with three site-years to determine the effects of seeding rate (130,000, 180,000, and 220,000 seeds acre⁻¹) in a triple-row configuration on soybean grain yield compared to a single-row configuration at 130,000 seeds acre⁻¹ on two soil textures (silt loam and clay). Both studies were repeated on silt loam and clay soil textures in every site-year. In the first study, the optimal planting date increased soybean grain yield regardless of soil texture. On both soil textures, twin- and single-row configuration yields were equivalent, but triple-row configuration reduced soybean grain yield up to 9%. Similarly, triple-row configuration reduced soybean density and height at R3 and R8 growth stages. In the second study, increasing triple-row configuration soybean seeding rate by at least 38% provided similar soybean grain yields to a single-row configuration at 130,000 seeds acre⁻¹. These data indicate that triple-row soybean planting configurations do have some benefits, but that future research should focus on equipment limitations experienced in the current research.

The response of tall fescue [Schedonorus arundinaceus (Schreb.) Dumort.], infected with fungal endophytes, and subjected to drought stress has varied, presumably due to variability in host–endophyte associations. Much of this research has focused on forage ecotypes; less is known about the effects of endophytes on managed turfgrasses. The objective of these trials was to determine if the presence of fungal endophytes in turf-type tall fescue provides an advantage to the host grass when exposed to drought conditions. Five endophyte-free and endophyte-infected field populations were established in Fayetteville, AR, and Albany, OR. A greenhouse trial was also established in Albany. Turf was subjected to drought and lightbox photos were evaluated to determine days until 75%, 50%, and 25% green cover. Overall, endophyte infection had no consistent effect on the drought response of tall fescue. Although there was no effect on drought response, endophyte infection in turf may confer other benefits, and may still be a valuable tool for turfgrass management.

Field studies in 2019–2020 evaluated the influence of fungicide application on seed quality from delayed harvest (approx. 20, 30, and 44 days after optimum harvest timing, i.e., 13% seed moisture). Treatments included nofungicide, pydiflumetofen plus difenoconazole (13.7 fl oz/acre Miravis Top, Syngenta), or mefentrifluconazole plus pyraclostrobin plus fluxapyroxad (8 fl oz/acre Revytek, BASF). Effect of environment was investigated in both field (natural rainfall events) and environmentally controlled growth chambers (79°F or 90°F with 30% or 100% relative humidity and exposed for 48 or 96 h) for potential impacts on soybean [Glycine max (L.) Merr.] seed quality. Seed quality was based on a rating scale of 1 to 10 with 1 being seeds in good condition and 10 being seeds in poor condition, based on USDA reference images. Fungicide application had no effect on seed quality from delayed harvest or a saturated environment (100% relative humidity). Delaying harvest beyond approximately 20 days past optimum timing can result in reduced seed quality regardless of fungicide application (1.0 to 2.0 vs 4.0 to 8.1 rating). In addition, seedpod exposure averaged across temperature and relative humidity environments for as little as 96 h after optimum harvest timing can result in deteriorating seed quality issues (3.2 vs 1.4 rating) regardless of fungicide application. Results indicate that soybean harvest delayed 20 days after optimum timing and subjected to seasonal rainfall events or seedpods exposed to completely saturated conditions for 96 h associated with a tropical weather event will result in soybean seed quality deterioration regardless of fungicide application.

The average U.S. peanut (Arachis hypogaea L.) yield has increased by approximately 25% with the adoption of peanut cultivar ‘Georgia-06G’. Since this adoption, many new high yielding runner cultivars with similar yield potential have been released. However, current nutrient recommendations are based on soil tests that were developed prior to the release of Georgia-06G. Particularly for potassium, current soil test potassium (STK) critical values were established on soil textures with relatively low cation exchange capacity (CEC) but were not validated on soil textures with high CEC. This study aimed to evaluate the growth and yield response of five recently released peanut cultivars to four STK levels ranging from very low to medium based on Mississippi State University Extension soil testing recommendations. The STK classification levels were also based on two soil series categorized with high CEC—Leeper (∼38.4 meq 100 g⁻¹) and Marietta (∼15.9 meq 100 g⁻¹) soil series. Cultivars Georgia-06G, ‘Georgia-16HO’, ‘Georgia-18RU’, FloRun ‘331’, and ‘AU-NPL-17’ were evaluated in this study. No STK × variety interaction occurred, indicating similar K requirements across all varieties evaluated. However, a positive pod yield response occurred in both soil types when the average STK increased from 128 to 167 lbs ac⁻¹ for all cultivars and site years. Critical STK values on both soils were greater than many current Extension recommendations, and the critical STK value of Leeper is greater than the Marietta soil series, likely due to the higher CEC value. These results demonstrate the need to adjust peanut STK sufficiency levels based on soil CEC. Further evaluation of modern peanut cultivar productivity response to STK sufficiency levels is needed for soils with moderate CEC.

North Carolina soybean [Glycine max (L.) Merr.] producers have shifted to earlier planting dates as a mechanism to increase soybean yields. As growers have shifted to earlier planting dates, soybean fungicide seed treatment use has become more common. In 2020 and 2021, on-farm research investigated the value of a fungicide seed treatment across the state. Experiments were conducted across 18 diverse production environments in North Carolina during that time. Treatments included fungicide seed treatment (fludioxonil: 2.32%, mefenoxam: 13.9%, and sedaxane: 2.32%, i.e., Vibrance Trio, a commonly used multi-mode of action fungicide across the state and country) compared to untreated seed. Data collected included soybean stand and soybean yield. The use of a fungicide seed treatment variably affected stand, but when combined over environments, fungicide seed treated plots averaged 110,757 plants/acre as opposed to untreated plots averaging 101,570 plants/acre with significant stand protection in seven of 18 environments. When averaged across environments, fungicide seed treatment protected yield by 1.3 bu/acre which, depending on input practices and soybean selling price, would border providing a return on investment. As planting date was delayed past mid-April, yield decreased for both fungicide treated and untreated plots. Results from this trial indicate that fungicide seed treatments can provide protection of soybean yield and stand in North Carolina although protection provided may not provide a return on investment with current input prices.

The potential adverse effects of glyphosate on glyphosate-resistant (GR) crops are still a matter of controversy. The effects of glyphosate at recommended application rates (either a single application of 580 g ae ha⁻¹ of glyphosate at stage V5 or a sequential application of 580 + 980 g ae ha⁻¹ at stage V3 and V7, respectively) on growth, mineral content, and metabolic parameters of GR maize (Zea mays) were determined in greenhouse and field studies, each replicated in different years. No effects on any growth parameter (including grain yield), mineral content (leaf and grain), grain starch, crude protein, or total lipids were found. The only significant negative effect was a slight reduction in tyrosine content of leaf tissue with the sequential treatment, however, there was no increase in shikimic or quinic acids in leaf tissue with any treatment. In a separate greenhouse experiment, there was no sign of oxidative stress, as determined by levels of chlorophylls, carotenoids, and malondialdehyde (MDA) content as well as superoxide dismutase and guaiacol peroxidase activities 4 and 8 days after treatment with 1080 g ha⁻¹ glyphosate. In fact, there was a reduction of MDA in roots of glyphosate-treated plants 4 DAT, indicating reduced oxidative stress. No aminomethylphosphonic acid, the primary degradation product of glyphosate, was found in either leaves or grain of treated plants, and no glyphosate was found in grain of treated plants from the field studies. All the results are consistent with there being no adverse effects of glyphosate on GR maize at recommended application rates.

Annual bluegrass (Poa annua L.) is sensitive to high-temperature stress, and approaches that can improve plant growth during summer months are important for golf courses managing P. annua putting greens. The objective of this 2-year field trial was to determine plant health benefits for selected fungicides and the combination with a plant growth regulator (PGR), trinexapac-ethyl (TE) on P. annua growth under putting green conditions during summer months. The following treatments were foliar sprayed at 14-day intervals from June to September in 2020 and 2021: (1) untreated control with water, (2) Daconil Action, (3) Appear II, (4) Daconil Action and Appear II, and (5) Daconil Action, Appear II, and Primo Maxx (TE). Applying individual and combination treatments resulted in significant improvements on P. annua summer performance, as manifested by increased visual turf quality and other vegetation indices evaluated using multispectral radiometer (normalized difference vegetation index, leaf area index, and stress index or digital camera [percent canopy cover and dark green color index]) in both years. The combined treatment programs, Daconil Action and Appear II or Daconil Action, Appear II, and Primo Maxx were more effective than the untreated control and each individual treatment. The results suggest that there existed synergistic effects of multiple fungicides and PGR, which could be particularly useful in promoting plant health of P. annua under heat stress conditions.

The majority of soils in the Mississippi Delta are vertisols, whose shrink–swell behavior makes them prone to waterlogging when subjected to excessive infiltration amounts from conventional management of furrow irrigation. The goal of this investigation was to examine if corn (Zea mays L.) grain yield and quality (test weight, kernel composition, and kernel weight) can be improved in vertisols of this region by widening furrow irrigation spacing while increasing furrow inflow rate proportionally to reduce waterlogging. A research station study at the National Center for Alluvial Aquifer Research and an on-farm study near Glen Allan, Mississippi, were conducted from 2021 to 2023. Furrow irrigation spacing treatments in the research station study included 3.3 ft, 6.7 ft, 13.3 ft, and 26.7 ft. The on-farm study included 10 ft, 20 ft, and “tractor track” (alternating between 10 and 30 ft furrow irrigation spacing) treatments. The three years of the research station study showed that the 26.7-ft treatment yielded 8.5% higher than the narrower treatments at the top position of the field (50–100 ft from the topographically higher end of 500 ft furrows). Higher grain protein and kernel weight were observed halfway between two irrigated furrows of the 13.3-ft and 26.7-ft treatments than adjacent to irrigated furrows of any treatment. Corn grain yield in the on-farm study was not significantly different among furrow irrigation spacing treatments. This research demonstrates that furrow irrigation spacing can be widened to at least 26.7 ft in vertisols of the Mississippi Delta without decreasing corn grain yield and quality.