Crop, Forage and Turfgrass Management最新文献

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.

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.

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.

Bermudagrass (Cynodon spp. Rich) is a warm-season grass that is widely planted throughout tropical, sub-tropical, and even temperate climates, and it generally requires fewer inputs than most cool-season turfgrasses. In recent years, the area of adaptation for bermudagrass has progressively expanded to cooler climates due to the development of more cold-tolerant cultivars. The expanded area of adaptation as well as the reduced inputs required to maintain healthy turfgrass have made bermudagrass a popular choice in areas of marginal adaptation. In these areas, the greatest threat to bermudagrass health and survivability is winterkill. This management guide seeks to describe winterkill: what it looks like, what causes it, and where it occurs. Additionally, this management guide describes best management practices to both prevent winterkill and recover bermudagrass from winterkill damage.

Poa annua L. has been identified as the most troublesome weed in turfgrass systems (Van Wychen, 2020). Its unwanted presence in turfgrass can undermine economic feasibility and performance by disrupting surface uniformity and increasing management costs. Controlling P. annua can be particularly challenging as it is a highly adaptive polyploid capable of surviving diverse environmental and management conditions (Carroll et al., 2021; Molina-Montenegro et al., 2016). This adaptability lends itself to widespread evolution of herbicide resistance, with confirmed resistance to at least 12 unique modes-of-action (MOAs) including several documented instances of multiple resistance (Breeden et al., 2017; Brosnan et al., 2015; Rutland et al., 2023; Singh et al., 2021).

While at least 50 distinct cases have been reported globally (Heap, 2023), the distribution of herbicide resistance in P. annua across climatic and management gradients has not been well documented. Among the documented cases of P. annua herbicide resistance collected from turfgrass or grass seed production systems (37 total), approximately 75% of biotypes were obtained from golf courses. Little to no herbicide resistance data has been reported for sports fields, lawns, and production turfgrass systems. This makes it difficult to discern and communicate the extent of herbicide resistance across the turfgrass industry and to correspondingly develop effective research and Extension strategies to address the problem. The latter is evidenced by recent studies that have identified localized skepticism, misinformation, and confusion about this issue across the turfgrass industry (Allen et al., 2022; Ervin et al., 2022).

This brief reports on findings from a multi-state survey evaluating the response of P. annua collections from various turfgrass management systems (i.e., golf courses, sports fields, residential and commercial lawns, sod production) to four herbicides and a plant growth regulator. The purpose of this survey was two-fold: (1) to establish a novel multi-state approach for the identification and advancement of P. annua collections with putative herbicide resistance across diverse climates and turfgrass systems; and (2) to discern potential trends related to P. annua proliferation and control that can inform future research and Extension strategies.

A previous report by Rutland et al. (2023) documented preliminary screening and sequencing of target-site mutations associated with four MOAs, including inhibitors of 5-enolpyruvylshikimate-3 phosphate synthase (Herbicide Resistance Action Committee [HRAC] Group 9, acetolactate synthase (HRAC Group 2), photosystem II (HRAC Group 5), and microtubule assembly (HRAC Group 3). Herein, we report screening results for paclobutrazol, a t

Although yield responses of soybeans [Glycine max (L.) Merrill] to nitrogen (N) fertilizer are rare, occasional yield increases, especially in high-yielding soybeans, have encouraged some producers to apply N. We conducted nine field experiments between 2014 and 2017 over a range of soil types and environments to evaluate soybean yield response to N (as urea) applied at planting, R1, R3, R5, and at all four timings. Our results showed that a single N application at R1 did not increase soybean yield in any location, while applying N at R3 or R5 increased grain yield in only one of nine locations. At a location with irrigated loam soils, N at planting increased grain yield by 22.4 bu ac⁻¹ (35%) in 2015 and 19.7 bu ac⁻¹ (38%) in 2016 but did not affect yield in 2017. Applying N four times did not increase yield more than the application at planting at this location in 2015 and 2016, but it increased yield in 2017. Four applications of N increased yield in three of the other six locations by an average of 5.0 bu ac⁻¹ (6%). Applying N four times or at R5 increased soil inorganic N at R6 at five of nine locations but did not consistently increase yield. Grain yield was positively correlated to Normalized Difference Vegetation Index (NDVI) taken at stage R6 at seven of the nine locations. Except for the yield increases from planting-time N at two locations, yield responses were insufficient to cover the cost of fertilizer N. While in-season application of fertilizer N to soybeans in productive Corn Belt soils in the United States is unlikely to be consistently profitable, N at planting that stimulates early growth and N uptake, especially in lighter-textured soils, may sometimes increase yield substantially.

Winter injury can cause significant loss of hybrid bermudagrasses [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt-Davy] in the transition zone. Current research has focused on high-value, low-acreage areas like putting greens, but those practices are impractical to implement on golf course fairways. To that end, multi-year research projects were conducted at three sites across Maryland and Virginia to investigate the influence of annual N fertility [2.0 lb N 1000 ft⁻² (early summer application) or 4.0 lb N 1000 ft⁻² (split applied early and late summer)] across multiple fall mowing heights (0.5 inches, 0.8 inches, or 1 inch) and to elucidate the effects of wetting agent (fall, fall + winter, or none) and irrigation (0.5 inches irrigation at <15% soil volumetric water content [VWC] or none) applications during dormancy on reducing winter injury of hybrid bermudagrass. Dry-down experiments were also conducted using plugs collected from field trials to impose an artificial freeze event and elucidate the effects of soil VWC on winter injury. Turfgrass quality and percent green cover were evaluated regularly as the turfgrass entered dormancy and throughout spring green-up each year. Late-season N applications helped retain fall green coverage without increasing winter injury and increasing fall mowing height did not impact winter injury. Temporary increase in soil VWC increased bermudagrass survival after a short-term freeze event and prevented root biomass loss. These studies demonstrate late-season N applications can help retain green color and increasing soil VWC prior to a short-term freezing event can greatly reduce winter injury.

This study aimed to quantify misses, overlaps, and oversprays on sports fields using different sprayer technologies across operator experience levels. Conducted from Winter 2022 to Summer 2023 at Veterans Park and Southwood Park in College Station, TX, identical studies were conducted on softball, baseball, and soccer fields. Employing a crossover design, six treatments were administered to three fields at each location, using manual, Global Navigation Satellite System (GNSS), and GNSS + autosteer sprayer technologies. Operators ranged from a highly experienced former sports field manager with nearly 20 years of experience to four inexperienced undergraduate students. Field boundaries were georeferenced for target area determination and treatment applications, using water and a spray volume of 65 gal per acre. ArcMap calculated percentage target area missed, overlapped, and oversprayed based on the actual versus intended volume sprayed. Data were subjected to analysis of variance, and means were separated using Fisher's protected LSD (α = 0.05). Applications by inexperienced operators using manual spray mode typically resulted in the highest rates of percentage target area missed and overlapped across locations and field types. The use of GNSS and autosteer technologithe percentagey reduced these errors and, consequently, percentage target area oversprayed. This enhancement in the consistency of applications led to a reduction of up to 4.6% in the total volume applied on the softball, baseball, and soccer fields. Therefore, the findings suggest that investing in GNSS-equipped sprayers with autosteer not only decreases the dependency on experienced operators but also minimizes errors and reduces total volume applied.